Do thermal fuses fail from old age?

[jeff_wisnia]

Over the years I've had a few thermal fuses in houshold appliances go
open for no apparent reason. When I've replaced them with ones with the
same temperature rating they stayed working fine for years more.

A couple of days ago our three year old Bunn coffee maker quit, because
a 141 degree celcius overtemperature thermal fuse on the water tank
opened. It might possibly have happened because the water tank
thermostat stuck closed, but after I repaired it the thermostat cycled
just as it should.

I was suprised to find that there were TWO identical thermal fuses
connected in series located right next to each other, the bodies were
actually touching. That seemed like a belt and suspenders approach,
unless there's a significant likelihood that a thermal fuse won't open
when it should?

Comments?

Thanks guys,

Jeff


--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.

[Tony Hwang]

jeff_wisnia wrote:
> Over the years I've had a few thermal fuses in houshold appliances go
> open for no apparent reason. When I've replaced them with ones with the
> same temperature rating they stayed working fine for years more.
>
> A couple of days ago our three year old Bunn coffee maker quit, because
> a 141 degree celcius overtemperature thermal fuse on the water tank
> opened. It might possibly have happened because the water tank
> thermostat stuck closed, but after I repaired it the thermostat cycled
> just as it should.
>
> I was suprised to find that there were TWO identical thermal fuses
> connected in series located right next to each other, the bodies were
> actually touching. That seemed like a belt and suspenders approach,
> unless there's a significant likelihood that a thermal fuse won't open
> when it should?
>
> Comments?
>
> Thanks guys,
>
> Jeff
>

Hi,
I understand they work on bi-metal strips. They can fail from fatigue.
Won't reset when temperature goes down cooling off.

[Phil Allison]

"Tony Hwang"

> I understand they work on bi-metal strips.

** Nope - that is a temperature switch.

Thermal fuses like this one use the melting point of some material and rely
on a spring to open the circuit.

http://media.digikey.com/photos/Cantherm%20Photos/SDJ1%20DF100S.jpg



.... Phil

[Larry Fishel]

On Mar 22, 12:17 am, "Phil Allison" <phi...@tpg.com.au> wrote:
> "Tony Hwang"
>
> > I understand they work on bi-metal strips.
>
> ** Nope -  that is a temperature switch.
>
> Thermal fuses like this one use the melting point of some material and rely
> on a spring to open the circuit.

But I assume the same applies. The metal heats up and expands somewhat
when in use and contracts when not. That will eventually cause it to
fail.

[Phil Allison]

"Larry Fishel"
"Phil Allison" :

> "Tony Hwang"
>
> > I understand they work on bi-metal strips.
>
> ** Nope - that is a temperature switch.
>
> Thermal fuses like this one use the melting point of some material and
> rely
> on a spring to open the circuit.

But I assume the same applies. The metal heats up and expands somewhat
when in use and contracts when not. That will eventually cause it to
fail

** Maybe so - but has nothing do with bloody bi-metal strips.



.... Phil

[micky]

On Thu, 22 Mar 2012 00:03:41 -0400, jeff_wisnia
<jwisnia...@conversent.net> wrote:

>Over the years I've had a few thermal fuses in houshold appliances go
>open for no apparent reason. When I've replaced them with ones with the
>same temperature rating they stayed working fine for years more.
>
>A couple of days ago our three year old Bunn coffee maker quit, because
>a 141 degree celcius overtemperature thermal fuse on the water tank
>opened. It might possibly have happened because the water tank
>thermostat stuck closed, but after I repaired it the thermostat cycled
>just as it should.
>
>I was suprised to find that there were TWO identical thermal fuses
>connected in series located right next to each other, the bodies were
>actually touching. That seemed like a belt and suspenders approach,
>unless there's a significant likelihood that a thermal fuse won't open
>when it should?

I wouldn't think they fail just from age, but what do I know?

I r eally posted to ask how you crimp them in place, what kind of
connector do you use?

And where do you buy them?

>Comments?

May it be our biggest problem.
>
>Thanks guys,
>
>Jeff

[bob haller]

I repair machines that use use them for a living, they are cheap
protection. they definetely nuisance trip for no reason. oh well it
keeps me working:)

they are so commonly used because of being so cheap. but it would be
far better if a resettable kind were used. lots of perfectly good
stuff must be tossed every year because a thermal fuse fatigued
failed.

I service roll laminating machines for a living. sael, GBC, Laminex,
USI, Idex, Ledco. Sadly nother manufacturer Banner just went out of
business after 38 years.

the economy is far worse than were being led to believe...............:
(

[Gareth Magennis]

"Phil Allison" <phi...@tpg.com.au> wrote in message
news:9svnff...@mid.individual.net...

This is the type Peavey have hidden in the mains transformer of the Classic
30.
I only discovered it by accident when I decided to dissect an "open circuit"
one, no mention in the schematics AFAIK.

The owner had had 2 mains transformers replaced previously, seems, from
Googling, these transformers are woefully underpowered and often break.
Wonder if the only failing part is actually this switch?


Gareth.

[Phil Allison]

"Gareth Magennis"
> "Phil Allison"

>>> I understand they work on bi-metal strips.
>>
>>
>> ** Nope - that is a temperature switch.
>>
>> Thermal fuses like this one use the melting point of some material and
>> rely on a spring to open the circuit.
>>
>> http://media.digikey.com/photos/Cantherm%20Photos/SDJ1%20DF100S.jpg
>
>

> This is the type Peavey have hidden in the mains transformer of the
> Classic
> 30.

** Eeee - yep.

> I only discovered it by accident when I decided to dissect an "open
> circuit"
> one, no mention in the schematics AFAIK.
>
> The owner had had 2 mains transformers replaced previously, seems, from
> Googling, these transformers are woefully underpowered and often break.
> Wonder if the only failing part is actually this switch?

** We must be leading parallel lives ..........

I actually have a power tranny from a PV Classic 30 in my used parts bin.

The thermal fuse was open - it resembled the one in my pic.

I replaced it with a new one of slightly higher temp rating and it works
fine.

The customer got a new tranny, as requested.



... Phil

[The Daring Dufas]

On 3/21/2012 11:03 PM, jeff_wisnia wrote:
> Over the years I've had a few thermal fuses in houshold appliances go
> open for no apparent reason. When I've replaced them with ones with the
> same temperature rating they stayed working fine for years more.
>
> A couple of days ago our three year old Bunn coffee maker quit, because
> a 141 degree celcius overtemperature thermal fuse on the water tank
> opened. It might possibly have happened because the water tank
> thermostat stuck closed, but after I repaired it the thermostat cycled
> just as it should.
>
> I was suprised to find that there were TWO identical thermal fuses
> connected in series located right next to each other, the bodies were
> actually touching. That seemed like a belt and suspenders approach,
> unless there's a significant likelihood that a thermal fuse won't open
> when it should?
>
> Comments?
>
> Thanks guys,
>
> Jeff
>
>

I could understand parallel fuses because one may not handle the
current. Perhaps in series it's safer because the unit will shut
off if one fails to open? o_O

TDD

[tra...@optonline.net]

On Mar 22, 12:03 am, jeff_wisnia <jwisniadumpt...@conversent.net>
wrote:

I had one of the hot water dispenser tank settups that goes
under the kitchen sink. A few years in, it failed due to the
thermal fuse failing for no reason. The original was no longer
available and had been replaced by a different type of design,
attachment method, etc. Looks to me like they had a
problem with them and changed the design.

I would suspect that part of the problem today is a lot of
the thermal fuses are being made in places like China with
poor quality control.

[N_Cook]

jeff_wisnia <jwisnia...@conversent.net> wrote in message
news:Su6dnWicsZ8DOffS...@giganews.com...

The larger resettable switch type are usually rated as combined
(self-heating) current and thermal cutout. Maybe similar for "Woods" metal
types , say if in circuit with fast switching on and off thermostat or poor
contacts , so repeated inrush curent combined with a standing temperature.

[Phil Hobbs]

Nasty cheap Chinese thermal fuses->higher rate of failure to open in a
real overtemp condition->using two in series may keep your house from
burning down, if they don't both fail the same way.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

[Tony Hwang]

Hi,
I fiddle with guitar amps. Son is into playing guitar/bass and drum.
Have a crude set up for recording as well. Have some vintage Marshall,
Fender, Boogie amp. Guytron and Soldano. Hugh & Kettner. Built couple
Fender clone and Marshall JMP clone from mono tube amp. Let kids blind
test it placing it side-by-side with real thing. They couldn't tell the
difference.

[N_Cook]

Phil Hobbs <pcdhSpamM...@electrooptical.net> wrote in message
news:4F6B3337...@electrooptical.net...

Perhaps the voltage rating was lower than the required use, ie in fused
state not rated for the service voltage across the broken section so someone
thought, I know , we'll put 2 in series ;-)

[William Sommerwerck]

Anything that heats up and cools down is likely to eventually fail from
thermal stress (including crystallization). (See Nevil Shute's novel "No
Highway".)

[jeff_wisnia]

Glad to hear that you've seen nuisance trips too, that makes me feel
like replacing the thermal fuse in our Bunn coffeemaker really "fixed it".

[jeff_wisnia]

The one I replaced is about the size of a 1/2 watt carbon resistor and
looks like this:

http://parts.digikey.com/1/parts/726774-thermal-fuse-141c-10a-axial-sdf-df141s.html

The way the original was installed The fuse's leads were left about an
inch long and the flexible insulated wires connecting to them were
fastened with little uninsulated metal crimps. I didn't have any of
those crimps so I just clamped a heat sink to the fuse's lead wire and
quickly soldered the flexible wire to the fuse lead with an 1/8 inch
long lap joint.

(Probably more than you needed to know, eh?)

[Tomsic]

"Larry Fishel" <ldfi...@yahoo.com> wrote in message
news:8d34fb90-87dd-4f35...@i2g2000vbv.googlegroups.com...

That's right; it's "metal fatigue" and those fuses which carry current close
to their limits do wear out faster. I'll also add corrosion. The metal at
the contact points of the fuse corrodes and makes for an intermittent
contact. I had a car once with all kinds of electrical problems -- wouldn't
start, lights flashed, horn didn't work, then it did. Finally replaced all
the fuses and the problems disappeared.

Tomsic

[jeff_wisnia]

The thermal fuse in our Bunn coffeemaker was marked as being made by
MicroTemp, labled series G7.

Just for Ss & Gs I looked them up today and learned that there's more
inside them than just a "fuse link" that melts at the trip temperature.

There's quite a bit of stuff in that little sucker.

Look here:

http://tinyurl.com/786eslm

[Phil Hobbs]

> Perhaps the voltage rating was lower than the required use, ie in fused
> state not rated for the service voltage across the broken section so someone
> thought, I know , we'll put 2 in series ;-)

Nah, even good equipment is made that way. I sort of collect
European-made espresso machines, and they all have two thermal fuses in
series with the thermostat. (I don't collect the fancy ones, you
understand--I just took a fancy to the long-discontinued Krups Il Primo,
because it has the best designed valve in the business. I've bought
about 5 off eBay at various times.)

Cheers

Phil Hobbs

[Phil Hobbs]

Works just like the little plastic things that come in Thanksgiving
turkeys.

Cheers

Phil Hobbs

[Jim Yanik]

"Gareth Magennis" <sound....@btconnect.com> wrote in
news:L6SdnfoCxPZWmPbS...@bt.com:

see if you can get to the thermal fuse and replace it with something rated
better,or just bypass it for test,using an external fuse.

ISTR reading in SER about others who eliminated the thermal fuse and
successfully reused transformers.


Also,consider how instrument amps are often used.(misused?)



--
Jim Yanik
jyanik
at
localnet
dot com

[Jeff Liebermann]

On Thu, 22 Mar 2012 00:03:41 -0400, jeff_wisnia
<jwisnia...@conversent.net> wrote:

>Over the years I've had a few thermal fuses in houshold appliances go
>open for no apparent reason. When I've replaced them with ones with the
>same temperature rating they stayed working fine for years more.
>
>A couple of days ago our three year old Bunn coffee maker quit, because
>a 141 degree celcius overtemperature thermal fuse on the water tank
>opened. It might possibly have happened because the water tank
>thermostat stuck closed, but after I repaired it the thermostat cycled
>just as it should.

Yep. See UL CHAT (conductive heat aging).
<http://www.intercontrol.de/00_img/pdf/article_TH100_en.pdf>
UL tests for thermal cutoff problems in appliances. The logic is that
if the thermal fuse is going to fail, it should always fail in the
direction of safety. So, if the cutoff threshold drifts, it should
always drift toward opening early. The same logic applies to thermal
type electrical circuit breakers, which are designed to lower the
threshold value after being tripped a few times.

>I was suprised to find that there were TWO identical thermal fuses
>connected in series located right next to each other, the bodies were
>actually touching. That seemed like a belt and suspenders approach,
>unless there's a significant likelihood that a thermal fuse won't open
>when it should?

The coffee distillery is double insulated, which means it doesn't need
a ground pin on the power plug. Since a fault can affect either side
of the power line in such a symmertical arrangement, two fuses are
required. Note that the thermal fuses also act as an internal short
protector. I doubt if the fuse died from CHAT. My guess is it had an
internal fault, probably from internal water accumulation during
washing, which blew the fuse.

>Jeff

Yet another Jeff.


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[micky]

No, not more. Exactly what I need to know.

I had thought about solder but feared it would melt the fuse, and I
have only one batch of about 6, each one a different temperature.
>
>Jeff

[jeff_wisnia]

In response:

The Bunn coffee maker we have uses a 3 pin grounding cord and plug.

The two thermal fuses were definitely in series with each other in the
hot side of the line feeding the thermostat controlling the storage tank
water temperature, and the also feeding the switch which controls the
"keep warm" heater under the carafe.

I think we've about "saucered and blowed" this subjuct by now, thanks all.

[Jules Richardson]

On Thu, 22 Mar 2012 05:53:14 -0700, tra...@optonline.net wrote:
> I would suspect that part of the problem today is a lot of the thermal
> fuses are being made in places like China with poor quality control.

I would suspect that part of the problem today is a lot of the thermal

fuses are being made in places like China, who will build to whatever
level of quality they're told to build to, and unfortunately there aren't
many of us who want to pay an extra ten cents for our product to ensure
that the fuses don't fail prematurely. ;-)

cheers

Jules

[Jules Richardson]

On Thu, 22 Mar 2012 11:25:06 -0400, Phil Hobbs wrote:
>> Look here:
>>
>> http://tinyurl.com/786eslm
>
> Works just like the little plastic things that come in Thanksgiving
> turkeys.

What, the bag of guts? ;)

[JIMMIE]

On Thursday, March 22, 2012 12:03:41 AM UTC-4, jeff_wisnia wrote:
> Over the years I've had a few thermal fuses in houshold appliances go
> open for no apparent reason. When I've replaced them with ones with the
> same temperature rating they stayed working fine for years more.
>
> A couple of days ago our three year old Bunn coffee maker quit, because
> a 141 degree celcius overtemperature thermal fuse on the water tank
> opened. It might possibly have happened because the water tank
> thermostat stuck closed, but after I repaired it the thermostat cycled
> just as it should.
>

> I was suprised to find that there were TWO identical thermal fuses
> connected in series located right next to each other, the bodies were
> actually touching. That seemed like a belt and suspenders approach,
> unless there's a significant likelihood that a thermal fuse won't open
> when it should?
>

> Comments?
>
> Thanks guys,

>
> Jeff
>
>
> --
> Jeffry Wisnia
> (W1BSV + Brass Rat '57 EE)
> The speed of light is 1.8*10e12 furlongs per fortnight.

Two fuses in series is pretty common. Always see this in microwave ovens and my wifes vacuum cleaner motor had two. Not sure if its belt and suspenders or just making it more likely to fail.

Jimmie

[Geoffrey S. Mendelson]

Jules Richardson wrote:

> I would suspect that part of the problem today is a lot of the thermal

> fuses are being made in places like China, who will build to whatever
> level of quality they're told to build to, and unfortunately there aren't
> many of us who want to pay an extra ten cents for our product to ensure
> that the fuses don't fail prematurely. ;-)

Not only that but the vendors at your end don't want them to last anyway.
Except for consumer electronics, people don't get rid of old items and buy
new ones because they are obsolete with enough frequency to keep them
in business.

They really do make it in volume, and not on single sales.

So if your coffee maker did not die after a year or two you would probably
be using it for the next 20 years.

The latest innovation in coffee makers is the cartridge ones, where the
profit is in the single use cartridges that you must buy.

I am packing up for a crosstown move, after 16 years in this apartment, and
I a finding kitchen items that I had when I moved in, some of which are still
in use everyday. Some I have had that are still in use, but not daily, since
the 1970's, but they are not electric.

Geoff.

--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(

[Stormin Mormon]

When I find myself needing insullated crimp. I take one of these,
http://i00.i.aliimg.com/photo/v0/228959260/non_insulated_ring_terminal.jpg
and cut the big loop off with diags, and use the small crimp ring
for my application.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"jeff_wisnia" <jwisniaDu...@conversent.net> wrote in message
news:jkfejv$rad$3...@dont-email.me...

[Stormin Mormon]

Home made crimps easy enough to make.
http://i00.i.aliimg.com/photo/v0/228959260/non_insulated_ring_terminal.jpg
Cut the big ring off with diags.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"micky" <NONONO...@bigfoot.com> wrote in message
news:rfjmm7tg3tg2f8m5p...@4ax.com...

[jeff_wisnia]

It gives me great joy to beat the manufacturers at that game Goeff.

Instead of spending about an hour driving to and from a Walmart to buy a
new Bunn Coffeemaker for $99.00 (plus 6.25% sales tax) I spent less than
a dollar on a thermal fuse and maybe half an hour in my workshop fixing
it while SWMBO cooked up a batch of eggplant melanzano (yummy) for
dinner. (She loves to cook and I love to fix busted things others have
to toss out.)

'Course the current miniscule size of todays electronics and my aging
eyesight makes it a no-win game for me to try and do much fixing of that
kind of stuff those days. 'Twas much easier in the vacuum tube era of my
youth 65 years or so ago when I occasionally even ecountered those old
fashioned resistors which were just round sticks of carbon composition
with right angle solid wire leads wrapped around each end, then painted
and color coded with paint dots.

Jeff

PS: Do you find folks screw around with the second "e" in your first
name by leaving it out or moving it ahead of the "r"?

My first name has only one "e" in it, but unless it goes from my
keyboard to an address or salutation without ever encountering a human
the odds are many to 1 that some jerk will assume I don't know how to
spell my own name and stick an extra "e" in it for me.

The spelling of my name isn't that unusual:

Google Hits on:

Jeffry 9.3 million

Jeffery 48.8 million

Jeffrey 264.0 million

But yours is the winner...

Geoffrey 86.2 million

Geoffry 0.812 million

Geoffery 1.8 million

[Phil Allison]

"Jeff Liebermann"

>
> The coffee distillery is double insulated, which means it doesn't need
> a ground pin on the power plug. Since a fault can affect either side
> of the power line in such a symmertical arrangement, two fuses are
> required.

** Horse manure.

One fuse is sufficient to break the circuit in case of current overload.

> Note that the thermal fuses also act as an internal short
> protector.

** Even worse horse manure.

Thermal fuses act on temperature, not current at all.

The max current rating given by makers is based on self heating to ensure
the fuse stays within temp rating tolerance.



.... Phil

[Michael A. Terrell]

N_Cook wrote:
>
> Perhaps the voltage rating was lower than the required use, ie in fused
> state not rated for the service voltage across the broken section so someone
> thought, I know , we'll put 2 in series ;-)

Which would do nothing, if they couldnn't handle the voltage.

Have you ever looked at the wiring in a furnace? They use multple
thermal shutdowns, for liability in the US.


--
You can't have a sense of humor, if you have no sense.

[N_Cook]

Michael A. Terrell <mike.t...@earthlink.net> wrote in message
news:OeGdncrMOvJ61_HS...@earthlink.com...

so you have no visual sense for emoticons

[The Daring Dufas]

It's known as H.I.S.I., pronounced "hissy", it describes the disease
Humor Irony Sarcasm Impairment. People with that particular mental
disease are said to have H.I.S.I. fits and often put on a big display of
pseudo-intellectualism about the subject at hand when they fail to see
the humor or bizarreness of statements made by someone who is attempting
to pull their leg. It's also called The Mr. Data response
in some circles. ^_^

P.S. They often get mad when someone like me is teasing them. o_O

TDD

[N_Cook]

The Daring Dufas <the-dari...@stinky.net> wrote in message
news:jkhorv$6ho$1...@dont-email.me...

The only theoretical justification I can come up with for having 2 same type
and batch thermal fuses in series is this possibility.
Over time they were getting returns where the then single fuse had blown but
no one could work out whether its due to heat or current carrying. Assuming
they have space to mount 2 in at production and one is closer to the
monitored source of heat than the other. Then if practically all the returns
showed the hotter one to have failed then its not so likely the cuurrent
carrying self-heating that is the issue.

[JW]

On Fri, 23 Mar 2012 07:04:16 -0500 The Daring Dufas
<the-dari...@stinky.net> wrote in Message id:
<jkhorv$6ho$1...@dont-email.me>:

>^_^

>o_O

Speaking of emoticons, those look like emoticons used by the late Matthew
Moulton, AKA DiaperBoy. Hmmm...

[The Daring Dufas]

Hatter isn't the only one to use them, they're actually common in Asia.
Besides, Matty was loads of fun to screw with and watch him melt down. :-)

TDD

[The Daring Dufas]

I do believe I wrote something like that early in the thread. ^_^

TDD

[Jeff Liebermann]

On Fri, 23 Mar 2012 13:33:04 +1100, "Phil Allison" <phi...@tpg.com.au>
wrote:

>
>"Jeff Liebermann"
>>
>> The coffee distillery is double insulated, which means it doesn't need
>> a ground pin on the power plug. Since a fault can affect either side
>> of the power line in such a symmertical arrangement, two fuses are
>> required.
>
>** Horse manure.

Yep. My neighbors just unloaded some Llama manure in their "garden".
Doesn't smell too bad.

>One fuse is sufficient to break the circuit in case of current overload.

<http://www.freewebs.com/valvewizard/fuses.html>
Some appliances use two fuses, one for live and one for
neutral. While there is some argument against using a
neutral fuse, there is no law against it (in the UK anyway).
You can buy IEC inlet sockets with built-in fuse holders,
which greatly simplifies construction.

<http://www.appliance411.com/faq/dryerheat.shtml>
There are 2 fuses or breakers for the dryer, both must
be good in order for the dryer to function properly.

>> Note that the thermal fuses also act as an internal short
>> protector.
>
>** Even worse horse manure.

Well, there are things worse than horse manure. I've never tried
skunk manure, but I suspect that would qualify.

>Thermal fuses act on temperature, not current at all.

True.

>The max current rating given by makers is based on self heating to ensure
>the fuse stays within temp rating tolerance.

The max current rating is the maximum current at which it will operate
safely without self-heating and blowing the fuse. I found out the
hard way that it's much like the rating on a typical wire fuse. If
you run a 5A fuse, at 5 amps at room temperature, it will eventually
blow. Same with a thermal fuse. If you run it near it's rated
maximum current (usually 5A, 15A, or 30A), it will eventually get warm
enough to melt the wax and trip the fuse. With a short circuit across
the power line, the self-heating will blow the thermal fuse almost
instantly. It's not designed to be a power fault protection device,
but does the job nicely anyway.

[Jeff Liebermann]

On Thu, 22 Mar 2012 19:30:18 -0400, jeff_wisnia
<jwisniaDu...@conversent.net> wrote:

>'Course the current miniscule size of todays electronics and my aging
>eyesight makes it a no-win game for me to try and do much fixing of that
>kind of stuff those days.

I use a microscope camera:
<http://www.ebay.com/itm/260969643003> $30
I have it plugged into a junk computah and LCD display. The original
plan was to attach it to a wrist strap, to make it easier for me to
see what I'm doing while soldering, but that didn't work. So, I now
use it on a plastic camera tripod, which works well. Saving the JPG's
has been handy for recording my work.

Unfortunately, I still have to wear my reading glasses in order to see
the LCD display. You can also use some cell phone cameras as a
microscope, if they have auto-focus (iPhone 3GS, most Droids, etc).

[William Sommerwerck]

> 'Course the minuscule size of today's electronics and my aging

> >eyesight makes it a no-win game for me to try and do much
> fixing of that kind of stuff those days.

I just bought an illuminated head-mount magnifier from Harbor Freight for
$5. It's surprisingly good. The optics have little distortion and no
chromatic aberration. There are four magnifications, but the lights "focus"
at only the lowest magnification.

[Jeff Liebermann]

I don't really like the plastic head mounted magnifiers. I'm
constantly going from whatever I'm working on, to picking up tools,
soldering iron, parts, probes, etc, on the bench. I have to keep
raising and lowering the magnifier in order to switch. With an LCD
screen, everything is roughly the same distance away, so no raising or
lowering.

If I were to buy a head mounted magnifier, it will probably be a
surgical loupe.
<https://www.google.com/search?q=surgical+loupe&tbm=isch>
Lots of styles and types to choose from, all seriously expensive. I've
played with some and am rather impressed. If I can keep the working
distance constant, it's as good or better than my USB camera
microscope. Mounted on eyeglasses, they are a bit heavy, but headband
mounts are available.

[Phil Hobbs]

Those things and drugstore reading glasses are great if you happen to
have just the right interpupillary distance. I buy lab glasses from
Zenni Optical for about $35 a pair--+0.75 diopter for reading, +2.5 for
close work, coated, good frames, just the right interpupillary distance
to avoid eyestrain. Highly recommended.

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

[Phil Allison]

"Jeff Liebermann = Nut Case Fuckwit "

>>
>>> The coffee distillery is double insulated, which means it doesn't need
>>> a ground pin on the power plug. Since a fault can affect either side
>>> of the power line in such a symmertical arrangement, two fuses are
>>> required.
>>
>>** Horse manure.
>
> Yep.

** Glad you agree- fuckwit.

>
>>One fuse is sufficient to break the circuit in case of current overload.
>
> <http://www.freewebs.com/valvewizard/fuses.html>
> Some appliances use two fuses, one for live and one for
> neutral. While there is some argument against using a
> neutral fuse, there is no law against it (in the UK anyway).
> You can buy IEC inlet sockets with built-in fuse holders,
> which greatly simplifies construction.

** Utterly irrelevant crap.

> <http://www.appliance411.com/faq/dryerheat.shtml>
> There are 2 fuses or breakers for the dryer, both must
> be good in order for the dryer to function properly.

** That schem shows TWO PHASE power being used.

You fucking tenth wit.

>>Thermal fuses act on temperature, not current at all.
>
> True.

** Glad you agree - fuckhead.

>>The max current rating given by makers is based on self heating to ensure
>>the fuse stays within temp rating tolerance.
>
> The max current rating is the maximum current at which it will operate
> safely without self-heating and blowing the fuse.

** There is only a few degrees of self heating at the rated current.

So to melt the material inside takes at least 5 times that current.

> I found out the
> hard way that it's much like the rating on a typical wire fuse. If
> you run a 5A fuse, at 5 amps at room temperature, it will eventually
> blow.

** Wire fuses run very hot at rated current, the wire inside may bend or
even glow in the dark - ie nothing like thermal fuses.

> Same with a thermal fuse.

** Blatant LIE.

> If you run it near it's rated
> maximum current (usually 5A, 15A, or 30A), it will eventually get warm
> enough to melt the wax and trip the fuse.

** MASSIVE BULLSHIT !!!!!!!!!!

> With a short circuit across
> the power line, the self-heating will blow the thermal fuse almost
> instantly.

** Nope - it will trip the supply breaker.

With a 10 times or more overload, breakers trip in a few milliseconds.

You stupid asshole.


... Phil

[Robert Green]

"jeff_wisnia" <jwisnia...@conversent.net> wrote in message
news:Su6dnWicsZ8DOffS...@giganews.com...

> Over the years I've had a few thermal fuses in houshold appliances go
> open for no apparent reason. When I've replaced them with ones with the
> same temperature rating they stayed working fine for years more.

Way back when, my dad used to do forensic engineering - analyzing various
disaster scenes to determine the cause. Thermal switches and circuit
protectors (which were often referred to generically (and incorrectly) as
"Klixons" did indeed fail from time to time. Usually they failed "safe" and
would interrupt the current flow, but on occasion they would "weld"
themselves together and fail to break the circuit. That's why you'll see
two of them in series on devices capable of self-ignition like coffee
makers, electric furnaces, etc. The likelihood of one failing is small, but
not negligible. Regrettably, it's happened often enough that many
manufacturers now use two is series. The probability of both failing
simultaneously *should* be pretty astronomical.

I recall one case dad investigated where the Klixon (and it really *was* a
Klixon branded unit) failed because the thermostat of a large electric
furnace had been wired incorrectly and the Klixon was actually doing the
turning on and off of the unit (very dangerous situation!). The expert sent
by the Klixon Corporation to testify said that the constant cycling of the
protective device as a switch caused a premature failure. He believed the
unit in question had been cycled 1,000's of times before it welded itself in
the closed position. The Klixons had been subjected to a fire of over 1,200
degrees F (determined by the "alligatoring" of the wood beams and the color
of the burned copper wiring). The fire damage to the unit made precise
metallurgical determination of the failure rather difficult.

That's when I learned (30+ years ago) that circuit breakers should not be
used as control devices unless they are specifically rated for that type of
use. I believe most are, nowadays, but that's not always been the case. I
think we've had this discussion before with lots of different opinions.
IIRC, even those breakers labeled SWD (switch duty) are only meant for
low-frequency applications such as turning the lights off and on once a day.

Not sure what the NEC has to say about it - I would think they would require
a switch, other than a circuit breaker, to control a load. However, I do
recall a number of people saying they routinely used the breaker panel to
kill lights, etc. in large stores and shops but it seems odd to me not to
require a switch in the circuit outside the circuit panel. That makes me
assume that the practice is allowed, at least in some jurisdictions. Maybe
there's a low-frequency exception involving lighting loads in large
buildings when using SWD-rated breakers.

A far worse risk (and one that seems to be committed far more often) is
resetting a tripped circuit breaker over and over again. That's definitely
a no-no in terms of asking for the protective device to fail. The fourth
time our kitchen breaker tripped was the signal to me that I needed to
install more 20A lines (eventually 3) to the kitchen. Great SAF. The
kitchen breakers haven't tripped in years. Only the GFCI's have nuisance
tripped in that time.

--
Bobby G.

[Michael A. Terrell]

N_Cook wrote:
>
> Michael A. Terrell <mike.t...@earthlink.net> wrote in message
> news:OeGdncrMOvJ61_HS...@earthlink.com...
> >
> > N_Cook wrote:
> > >
> > > Perhaps the voltage rating was lower than the required use, ie in fused
> > > state not rated for the service voltage across the broken section so
> someone
> > > thought, I know , we'll put 2 in series ;-)
> >
> >
> > Which would do nothing, if they couldnn't handle the voltage.
> >
> > Have you ever looked at the wiring in a furnace? They use multple
> > thermal shutdowns, for liability in the US.
>

> so you have no visual sense for emoticons

I did too many fire restoration jobs after a pair of switches failed
and people died. I see no humor in people dying from failed and jury
rigged repairs. Laugh all you want. It fits you.

[Michael A. Terrell]

The Daring Dufas wrote:
>
> P.S. They often get mad when someone like me is teasing them. o_O

Some just consider the source, and ignore you.

[Jeff Liebermann]

On Thu, 22 Mar 2012 10:12:07 -0400, Phil Hobbs
<pcdhSpamM...@electrooptical.net> wrote:

>Nasty cheap Chinese thermal fuses->higher rate of failure to open in a
>real overtemp condition->using two in series may keep your house from
>burning down, if they don't both fail the same way.

Maybe. Such guesswork would be greatly reduced if the original poster
would kindly provide the Braun model number.
<https://www.google.com/search?&q=braun+coffee+maker&tbm=isch>

If the coffee maker is of the drip type automatic variety, then there
are two heaters. The upper heater, that heats the water before it
goes through the coffee filter, and the warmer at the base, that keeps
the pot of coffee warm. Such a derrangement requires two thermal
fuses, one for each heater.

Incidentally, I had a really old Mr Coffee maker overheat and melt the
plastic case. The thermal fuse never blew. The consensus was that
water somehow invaded the Microtemp thermal fuse, and rusted
everything in place.

[The Daring Dufas]

I repaired a furnace for one of my favorite customers, a little old lady
about 90 who had her children and grandchildren staying with her
and she had no heat. I found that water flooding the basement had
shorted out the control board for her furnace but some moron had
bypassed the roll-out safety switch on the furnace because another
safety wasn't working. Needless to say, I had to replace a whole section
of the wiring harness because the flames blew back from the burners
destroying the wiring. It was a lucky break that the burned wiring
shorted out killing the furnace or I fear the house would have caught
fire with all those folks in there. I wish I could get my hands around
the neck of the asshole who decided it was a good idea to bypass the
safety switches on that furnace. o_O

TDD

[Michael A. Terrell]

I used to subcontract electronic repair for a fire restoration
company. Most of their jobs were to repair the buildings so the heirs
could sell them. They wanted nothing to do with the place their parent
or parents died. More than one death was caused by an incompetent
repair. A thermal overload failed? No big deal: "he terminals on the
wires will push together, so all I need is some tape and I'll charge the
suckers a couple hundred dollars." :(
>
> TDD

[Jim Yanik]

Jeff Liebermann <je...@cruzio.com> wrote in
news:unjpm79is43h64it9...@4ax.com:

> On Thu, 22 Mar 2012 19:30:18 -0400, jeff_wisnia
><jwisniaDu...@conversent.net> wrote:
>
>>'Course the current miniscule size of todays electronics and my aging
>>eyesight makes it a no-win game for me to try and do much fixing of that
>>kind of stuff those days.
>
> I use a microscope camera:
><http://www.ebay.com/itm/260969643003> $30
> I have it plugged into a junk computah and LCD display. The original
> plan was to attach it to a wrist strap, to make it easier for me to
> see what I'm doing while soldering, but that didn't work. So, I now
> use it on a plastic camera tripod, which works well. Saving the JPG's
> has been handy for recording my work.
>
> Unfortunately, I still have to wear my reading glasses in order to see
> the LCD display. You can also use some cell phone cameras as a
> microscope, if they have auto-focus (iPhone 3GS, most Droids, etc).
>
>
>

I have reading glasses(2.75X) and also have a separate binocular magnifier
of 2.5X.

you can buy "clip-on" binocular magnifiers for pretty low cost on Ebay,I
got mine for $5 USD,plus shipping. they either clip on your regular
glasses,or clip on their own eyeglass frame. They are easier to see around
than the hobby binoc flip-up magnifiers,when you don't need close up
vision,you don't have to move them out of the way.

--
Jim Yanik
jyanik
at
localnet
dot com

[The Daring Dufas]

That's basically what the idiot did and I come across that sort of thing
all the time across the many fields I work in. My friend GB
who owned the mechanical company I often helped him with was very
much like me in that we couldn't live with ourselves if we were to
cheat folks. GB passed away last fall so I'm not doing much in the
way of residential HVAC work but there is enough commercial work to
keep me occupied along with all the other stuff. I see incompetent
work and dangerous shortcuts quite often and I make sure the customer
is aware of how dangerous that sort of thing is and I would be
absolutely devastated if someone were harmed because of something I
did, especially if it was a child. If you've ever come across the
website "There, I Fixed It" and seen some of the insane shortcuts and
godawful dangerous things people do you may laugh like I do because I've
actually seen people do the same crazy things. o_O

TDD

[Michael A. Terrell]

Ever looked at "White Trash Repairs"? Some dangerous idiots on that
site like the guy who blows up microwave ovens, or the one making
fireworks in his house. :(


The losers who do some electrical work should have to live in the
houses they wire.

I installed the computer networking, fire alarms and TV antenna
systems at a new college campus years ago. The HVAC crew was the
biggest idiot's I've ever had the misfortune to work around. The
blueprints showed where every air handler was supposed to go, so that
the ducting would have plenty of clearance. They not only set them in
the wrong places, one was backwards, with their wiring hanging from the
20 foot ceilings. the gofer for the general contractor kept running
around pulling the fire boxes while I was trying to test the prewire,
until I caught him in the act. I followed him to his bosses office and
read him the riot act. Then I promised to kick his sorry ass all the
way across the campus if anyone pulled another box. he told me I
couldn't do it, but his boss said that he would be a fool to try, and
find out for sure. :)

When it was time for the state inspector & his punch list he said the
system failed, because the glass break rods were missing. I told him
they would be installed, but only after the building was accepted and
that the weren't installed due to over 100 attempts to cause a false
alarm.

That was the last time I did any sub work for that electrical
contractor.

[The Daring Dufas]

> When it was time for the state inspector& his punch list he said the

> system failed, because the glass break rods were missing. I told him
> they would be installed, but only after the building was accepted and
> that the weren't installed due to over 100 attempts to cause a false
> alarm.
>
> That was the last time I did any sub work for that electrical
> contractor.
>

I will no longer tolerate sabotage or someone fooling around with my
work on a construction project. I've decided the best thing to do is
call the police and file a report along with a dollar value of the
damage based on my highest hourly rate. I will definitely have one of
perpetrators jailed on felony charges if the dollar amount is enough.
The police reports come in handy for a lawsuit against a contractor
with a "Screw You!" attitude.

I was doing some control work with an engineer friend of mine I had met
when we worked on a construction project for The Star Wars "SDI" program
back in the 80's and we were installing a large HVAC control system for
a new school in the 90's and on that job, one of the young don't give a
damn electricians decided to cut and pull our control wire out of a roof
penetration conduit so he could use it. The conduit was 40' in the air
and luckily one of the other electricians told us before the ceiling was
installed. The kid's excuse for ripping out our wire was that it was in
his way and when asked why he didn't tell us so we could handle the
problem was the fact that we weren't there that day. I don't know if
personal civilian Tasers were available at the time but I would have
liked to have owned one. ^_^

P.S. Some day I'll have to tell you of my adventures the with the Halon
fire suppression system I installed in Mission Control at the missile
range. o_O

TDD

[Jeff Liebermann]

On Fri, 23 Mar 2012 22:36:09 -0400, "Michael A. Terrell"
<mike.t...@earthlink.net> wrote:

> Ever looked at "White Trash Repairs"?

<http://thereifixedit.failblog.org>

[Stormin Mormon]

Maybe their thermal fuses opened?

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message

news:QrSdnXQ6WIYWbvHS...@earthlink.com...

[Stormin Mormon]

Not only thermal fuses, as you've found. I've also seen compressor thermal
overloads hanging loose in the air. With the compressor cooking hot.

One other one I saw, was a dehumidifier (commercial model, mounted in a
cellar) that would regularly freeze over. I had a look, and find the freeze
sensor hanging in the air, rather than clipped to the (frozen) suction line.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message

news:FrednQk4e6iqjfDS...@earthlink.com...

I used to subcontract electronic repair for a fire restoration
company. Most of their jobs were to repair the buildings so the heirs
could sell them. They wanted nothing to do with the place their parent
or parents died. More than one death was caused by an incompetent
repair. A thermal overload failed? No big deal: "he terminals on the
wires will push together, so all I need is some tape and I'll charge the
suckers a couple hundred dollars." :(

[Stormin Mormon]

Reminds me of the one time I was helping extend some HVAC duct work. The
other fellow had spent all day cutting a rectangle shaped hole in a
cinderblock wall. We came back the next day, the cable TV installer had run
a wire diagonally through our hard won duct hole. I suggested taking the
wire out with diags.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"The Daring Dufas" <the-dari...@stinky.net> wrote in message

news:jkjom7$7c6$1...@dont-email.me...

I was doing some control work with an engineer friend of mine I had met
when we worked on a construction project for The Star Wars "SDI" program
back in the 80's and we were installing a large HVAC control system for
a new school in the 90's and on that job, one of the young don't give a
damn electricians decided to cut and pull our control wire out of a roof
penetration conduit so he could use it. The conduit was 40' in the air
and luckily one of the other electricians told us before the ceiling was
installed. The kid's excuse for ripping out our wire was that it was in
his way and when asked why he didn't tell us so we could handle the
problem was the fact that we weren't there that day. I don't know if
personal civilian Tasers were available at the time but I would have
liked to have owned one. ^_^

TDD

[Stormin Mormon]

I'd like to hear. I've learned a litle about these, but I'm sure your first
hand experience will be interesting.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"The Daring Dufas" <the-dari...@stinky.net> wrote in message
news:jkjom7$7c6$1...@dont-email.me...

[Stormin Mormon]

I've seen some moments when people weren't working together. But sabotage?
It's a shame that people make life dificult for each other, on purpose.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"The Daring Dufas" <the-dari...@stinky.net> wrote in message
news:jkjom7$7c6$1...@dont-email.me...

I will no longer tolerate sabotage or someone fooling around with my
work on a construction project. I've decided the best thing to do is
call the police and file a report along with a dollar value of the
damage based on my highest hourly rate. I will definitely have one of
perpetrators jailed on felony charges if the dollar amount is enough.
The police reports come in handy for a lawsuit against a contractor
with a "Screw You!" attitude.

TDD

[William Sommerwerck]

"Infinite Energy 3.0" is wonderful. The creator went to a lot of trouble to
set it up.

[bob haller]

My job involves repairing machines with thermal fuses. does anyone
make 20 amp or 30 amp rated ones?

the machines i repair have 15 amp thermal fuses on high inrush loads,
and the fuses fatigue fail from being close to or at their current
limit. the machines draw a instaneous 20 amps for a moment on start up

i would rather install a higher amp fuse, of the right temp, and save
tons of time and gasoline replacing the same part over and over
again.........

[Jeff Liebermann]

On Sat, 24 Mar 2012 09:24:35 -0700 (PDT), bob haller <hal...@aol.com>
wrote:

>My job involves repairing machines with thermal fuses. does anyone
>make 20 amp or 30 amp rated ones?

<http://www.thermodisc.com/uploads/specs/TCO.pdf>
G8 series goes to 25A.

[jeff_wisnia]

Jeff Liebermann wrote:
> On Thu, 22 Mar 2012 10:12:07 -0400, Phil Hobbs
> <pcdhSpamM...@electrooptical.net> wrote:
>
>
>>Nasty cheap Chinese thermal fuses->higher rate of failure to open in a
>>real overtemp condition->using two in series may keep your house from
>>burning down, if they don't both fail the same way.
>
>
> Maybe. Such guesswork would be greatly reduced if the original poster
> would kindly provide the Braun model number.
> <https://www.google.com/search?&q=braun+coffee+maker&tbm=isch>
>
> If the coffee maker is of the drip type automatic variety, then there
> are two heaters. The upper heater, that heats the water before it
> goes through the coffee filter, and the warmer at the base, that keeps
> the pot of coffee warm. Such a derrangement requires two thermal
> fuses, one for each heater.
>
> Incidentally, I had a really old Mr Coffee maker overheat and melt the
> plastic case. The thermal fuse never blew. The consensus was that
> water somehow invaded the Microtemp thermal fuse, and rusted
> everything in place.
>

Our Bunn is a Model GRX.

The two thermal series connected fuses are both located side by side on
top of the heated water tank.

There was no accessable thermal fuse I could see located on the warmer
heater, but maybe one was buried inside it.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.

[mjb]

TDD - Please fix your newsreader so it indents the previous poster's
contribution. It's very confusing when its all at the same indent level.

[Stormin Mormon]

Would it help to put two thermals, in parallel?

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"bob haller" <hal...@aol.com> wrote in message
news:09dac57f-fa1a-49b6...@r27g2000vbn.googlegroups.com...

[Jeff Liebermann]

On Sat, 24 Mar 2012 14:04:36 -0400, "Stormin Mormon"
<cayoung61***spam...@hotmail.com> wrote:

>Would it help to put two thermals, in parallel?

No. You could not guarantee that the current would split evenly
between the two thermal fuses. A more serious problem is that it
would require BOTH thermal fuses to blow in order to protect the
appliance.

[Jeff Liebermann]

On Sat, 24 Mar 2012 13:11:45 -0400, jeff_wisnia
<jwisniaDu...@conversent.net> wrote:

>Our Bunn is a Model GRX.

Thanks. Is it GRX-B, GRX-W, GRX-Basic???
<http://www.walmart.com/ip/Bunn-O-Matic-10-cup-Black-Professional-Coffee-Brewer-GRX-B/4891346>
<http://www.bunnathome.com/products/velocity-brew/velocity-brew-gr>
<http://www.bunnathome.com/sites/bunnathome.com/files/GR_use&carebooklet_english.pdf>
That style would require two thermal fuses. One on top and one on the
warmer. I couldn't find anyone selling internal repair parts that
might also have an exploded view showing the fuses.

Looks like it has a 3 year warranty. Find your receipt.
Support 1-800-352-2866. Call and ask.

>The two thermal series connected fuses are both located side by side on
>top of the heated water tank.

Well, that's the most likely to overheat, but it certainly would not
require two fuses to do the job. Something is wrong here.

>There was no accessable thermal fuse I could see located on the warmer
>heater, but maybe one was buried inside it.

Maybe, but more likely the factory forgot to install one on the
warmer. So they put it where it would fit easily, which is next to
the upper heater fuse. QA? Whazzat?

[Roy]

Actually, Stormin Mormin is the one with the broken newsreader.

[jeff_wisnia]

Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.

Jeff Liebermann wrote:
> On Sat, 24 Mar 2012 13:11:45 -0400, jeff_wisnia
> <jwisniaDu...@conversent.net> wrote:
>
>
>>Our Bunn is a Model GRX.
>
>
> Thanks. Is it GRX-B, GRX-W, GRX-Basic???
> <http://www.walmart.com/ip/Bunn-O-Matic-10-cup-Black-Professional-Coffee-Brewer-GRX-B/4891346>
> <http://www.bunnathome.com/products/velocity-brew/velocity-brew-gr>
> <http://www.bunnathome.com/sites/bunnathome.com/files/GR_use&carebooklet_english.pdf>
> That style would require two thermal fuses. One on top and one on the
> warmer. I couldn't find anyone selling internal repair parts that
> might also have an exploded view showing the fuses.
>
> Looks like it has a 3 year warranty. Find your receipt.
> Support 1-800-352-2866. Call and ask.
>
>
>>The two thermal series connected fuses are both located side by side on
>>top of the heated water tank.
>
>
> Well, that's the most likely to overheat, but it certainly would not
> require two fuses to do the job. Something is wrong here.
>
>
>>There was no accessable thermal fuse I could see located on the warmer
>>heater, but maybe one was buried inside it.
>
>
> Maybe, but more likely the factory forgot to install one on the
> warmer. So they put it where it would fit easily, which is next to
> the upper heater fuse. QA? Whazzat?
>

I'm finding it somewhat hard to believe that the warmer heater would
overheat, since there's no thermostat in or on it which could fail in
the closed mode and cause such overheating.

I'll await comments from others regarding the need and/or usage of a
thermal fuse on the warmer.

Jeff

[Jeff Liebermann]

On Sat, 24 Mar 2012 08:48:09 +1100, "Phil Allison" <phi...@tpg.com.au>
wrote:

>> If you run it near it's rated
>> maximum current (usually 5A, 15A, or 30A), it will eventually get warm
>> enough to melt the wax and trip the fuse.
>
>** MASSIVE BULLSHIT !!!!!!!!!!
>
>> With a short circuit across
>> the power line, the self-heating will blow the thermal fuse almost
>> instantly.
>
>** Nope - it will trip the supply breaker.
>
> With a 10 times or more overload, breakers trip in a few milliseconds.
>
> You stupid asshole.

See: UL 60691 for testing of the the thermal fuse:
<http://bbs.dianyuan.com/bbs/u/32/1122972217.pdf>
Section 10.8 discusses its use as a short circuit protection
overcurrent fuse. (This is rev 3. Rev 5 is the current version).

[Jeff Liebermann]

On Sat, 24 Mar 2012 18:55:44 -0400, jeff_wisnia
<jwisniadu...@conversent.net> wrote:

>I'm finding it somewhat hard to believe that the warmer heater would
>overheat, since there's no thermostat in or on it which could fail in
>the closed mode and cause such overheating.

UL coffee maker standards:
<http://ulstandardsinfonet.ul.com/scopes/1082.html>
<http://bbs.dianyuan.com/bbs/u/33/1127541096.pdf>
Section 18.x for thermal cutoff requirements.
Section 23.x for whether a thermal cutoff is required.
Table 33.1 shows the maximum temperature rise allowed. As I read
between the lines, any part that might rise above the stated
temperatures, requires a thermal fuse.

UL 60691 for testing of the thermal fuse:
<http://bbs.dianyuan.com/bbs/u/32/1122972217.pdf>
Section 10.8 discusses its use as a short circuit protection fuse.

You might find this interesting:
<http://www.fixya.com/search/p89511-bunn_nhb_coffee_maker/thermal_fuse>
It's a different model Bunn coffee maker, but the problems are
probably similar.

>I'll await comments from others regarding the need and/or usage of a
>thermal fuse on the warmer.

Ah, truth by consensus and acclamation. Much as I like the concept,
I've seen it fail far too often.

[Robert Green]

"Jeff Liberian" <je...@cruzio.com> wrote in message
news:ubnsm7d9jgsucm7sd...@4ax.com...

> On Sat, 24 Mar 2012 18:55:44 -0400, Jeff_wins
> <jwisniadu...@conversent.net> wrote:


> >I'll await comments from others regarding the need and/or usage of a
> >thermal fuse on the warmer.
>
> Ah, truth by consensus and acclamation. Much as I like the concept,
> I've seen it fail far too often.

If I were to reassemble the device differently than the way it was designed,
I would be certain to run it in an area with nothing nearby that could catch
fire for a while to see if the consensus was correct. (-:

Protection devices are sometimes added to products when beta testing reveals
a potentially dangerous condition. Their requirement might not be obvious
by simple inspection later on.

I would only omit a fuse or protective device if it was impossible to find
an identical replacement. Even then, I would probably use the most similar
component I could find. We're talking about a device that's often operating
out a human's presence that has ignition potential. Bad kimshi.

--
Bobby G.

[Stormin Mormon]

Well, Bob Haller said he had 15 amp thermals, and occasional 20 amp inrush.
Why would that need to be "current split evenly"? Supposing they are
carrying 15 amps and 5 amps. What's the problem?

If the thermals are properly placed, they would both melt open when the
device overheated.

And suppose one thermal fails from old age? Then, Bob is back where he was
when he started.

I don't see the big problem.

Christopher A. Young
Learn more about Jesus
www.lds.org
.

"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:s86sm7t4uqtl8v415...@4ax.com...

[bob haller]

On Mar 25, 7:53 am, "Stormin Mormon"

<cayoung61***spambl...@hotmail.com> wrote:
> Well, Bob Haller said he had 15 amp thermals, and occasional 20 amp inrush.
> Why would that need to be "current split evenly"? Supposing they are
> carrying 15 amps and 5 amps. What's the problem?
>
> If the thermals are properly placed, they would both melt open when the
> device overheated.
>
> And suppose one thermal fails from old age? Then, Bob is back where he was
> when he started.
>
> I don't see the big problem.
>
> Christopher A. Young
> Learn more about Jesus
>  www.lds.org
> .
>
> "Jeff Liebermann" <je...@cruzio.com> wrote in message
>
> news:s86sm7t4uqtl8v415...@4ax.com...
> On Sat, 24 Mar 2012 14:04:36 -0400, "Stormin Mormon"
>

> <cayoung61***spambl...@hotmail.com> wrote:
> >Would it help to put two thermals, in parallel?
>
> No.  You could not guarantee that the current would split evenly
> between the two thermal fuses.  A more serious problem is that it
> would require BOTH thermal fuses to blow in order to protect the
> appliance.
>
> --
> Jeff Liebermann     je...@cruzio.com
> 150 Felker St #D    http://www.LearnByDestroying.com

> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann     AE6KS    831-336-2558

I have used thermal fuses in parell. But really dont like it as it
would cause too many problems if a fire occured.

thanks for the link for the high current thermal fuses anything that
decreases my gasoline expense is well worth it.........

[Jeff Liebermann]

On Sun, 25 Mar 2012 07:53:23 -0400, "Stormin Mormon"
<cayoung61***spam...@hotmail.com> wrote:

>Well, Bob Haller said he had 15 amp thermals, and occasional 20 amp inrush.
>Why would that need to be "current split evenly"? Supposing they are
>carrying 15 amps and 5 amps. What's the problem?

A 15A thermal fuse will not blow on a 20A inrush. It needs some time
to melt the wax inside the fuse and blow. I'm not sure how much is
required to blow it up reliably, but a short circuit across the line
should do the trick.

The problem with unequal current distribution is that the fusing
current is not predictable. However, you're partially correct. If
one fuse blows at some current, the full current load will transfer to
the other parallel fuse, which will then have enough current to blow.
The problem is that if it takes one minute for the first fuse to blow,
it will probably take more than an additional minute to blow the 2nd
fuse because of the higher series resistance which is what causes the
unequal current distribution in the first place. In effect, such a
derangement extends the time it takes for the power to be cut, and a
fire prevented.

>If the thermals are properly placed, they would both melt open when the
>device overheated.

That's a big if. Presumably, if the heating element was one
contiguous device, with no possibility of a partial short to the metal
water tank, there would be no thermal gradient across the water tank.
However, if the heater was a series of heating elements, distributed
in some artistic pattern across the bottom of the water tank, and only
a partial short occurs, the resulting thermal gradient will cause one
thermal fuse to be much hotter than the other, especially if the water
tank is empty.

>And suppose one thermal fails from old age? Then, Bob is back where he was
>when he started.

From: UL 60691 Pg 17
NOTE 2 For reasons of safety, it should be made clear in the
documentation that a THERMAL-LINK is a non-repairable item
and that, in case of replacement, an equivalent THERMAL-LINK
from the same manufacturer and having the same catalogue
reference should be used, mounted in exactly the same way.
This might explain why every pot warmer I could find has the plastic
base solvent welded shut, or metal base riveted together, to prevent
(or at least discourage) thermal fuse replacement.

However, in the case of the coffee machine, UL contradicts itself:
From: UL 1082 Pg 26
18.1 If an appliance is provided with a thermal cutoff, it
shall be secured in place and shall be so located that it will
be accessible for replacement without damaging other connections
or internal wiring. See 50.6.

So, one spec says it should be un repairable, while another says that
it should be accessible for replacement. Toss a coin.

Incidentally, if the thermal fuse blows, one should consider asking
why it blew. It isn't always old age or crappy quality. There may be
an intermittent or obscure fault causing it to blow.

>I don't see the big problem.

Look harder and you'll see. What you're suggesting is not in itself
unsafe. It is possible to run parallel thermal fuses and still have
it perform its intended function. However, it's much safer to put
them in series.

[bob haller]

On Mar 25, 7:01 pm, Jeff Liebermann <je...@cruzio.com> wrote:
> On Sun, 25 Mar 2012 07:53:23 -0400, "Stormin Mormon"
>

> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann     AE6KS    831-336-2558

a 15 amp thermal fuse on a high inrush load causes premature failure
of the fuse, not from device malfunction but the repeated high current
rush.

this can and does cause cause the thermal fuse to fail while the
device is fine.

with gasoline so expensive i want to minimize unnecessary calls. they
annoy the customer and waste my time.//

I am ordering some high current thermal fuses in the AM

[Jeff Liebermann]

On Sun, 25 Mar 2012 20:24:33 -0700 (PDT), bob haller <hal...@aol.com>
wrote:

>a 15 amp thermal fuse on a high inrush load causes premature failure
>of the fuse, not from device malfunction but the repeated high current
>rush.
>
>this can and does cause cause the thermal fuse to fail while the
>device is fine.
>
>with gasoline so expensive i want to minimize unnecessary calls. they
>annoy the customer and waste my time.//
>
>I am ordering some high current thermal fuses in the AM

What is the device? I ask because it might be easier to install a
thermistor inrush current limiter on the input power leads, than a
bigger thermal fuse.

Inrush current limiting devices:
<http://www.ametherm.com/inrush-current/>
<http://www.rtie.com/category-s/48.htm>
According to the data sheets they have devices rated from 1 to 36
amps.

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com

Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[The Daring Dufas]

On 3/25/2012 11:08 PM, Jeff Liebermann wrote:
> On Sun, 25 Mar 2012 20:24:33 -0700 (PDT), bob haller<hal...@aol.com>
> wrote:
>
>> a 15 amp thermal fuse on a high inrush load causes premature failure
>> of the fuse, not from device malfunction but the repeated high current
>> rush.
>>
>> this can and does cause cause the thermal fuse to fail while the
>> device is fine.
>>
>> with gasoline so expensive i want to minimize unnecessary calls. they
>> annoy the customer and waste my time.//
>>
>> I am ordering some high current thermal fuses in the AM
>
> What is the device? I ask because it might be easier to install a
> thermistor inrush current limiter on the input power leads, than a
> bigger thermal fuse.
>
> Inrush current limiting devices:
> <http://www.ametherm.com/inrush-current/>
> <http://www.rtie.com/category-s/48.htm>
> According to the data sheets they have devices rated from 1 to 36
> amps.
>

Back about 4 decades when I tried my hand at TV repair, me and the guys
I worked with had to replace a lot of what were called
"glowbars/globars", they were actually PTC devices hooked to the
degaussing coil around the CRT of a TV set to power the degaussing coil
for a short period every time a TV set was turned on. When you first
turn on a TV or CRT monitor equipped with one you may hear a "GRONK"
sound and that's the degaussing circuit. The PTC thermistor allows a big
rush of current to the coil until it heats up which causes its
resistance to increase stopping the flow of current until it cools off.
There could be a way to use a globar and one of those mil spec power
resistors in that finned aluminum case that has mounting ears and one
flat surface. The resister could be epoxied to the metal in the
appliance and hooked in series with the thermistor across the incoming
power to temper any inrush current before it hit the heating element
circuit. I see several diagrams forming in my mind's eye including one
with a low value power resister in series with the heating element
connected to the thermistor circuit and another with an NTC device in
series with the heating element and the power. The only problem would be
coming up with a thermistor that could handle the current of the heating
element when it's connected in series with it. Oh well, it's my mind,
I'll have fun playing in there. ^_^

TDD

[Jeff Liebermann]

On Mon, 26 Mar 2012 00:53:26 -0500, The Daring Dufas
<the-dari...@stinky.net> wrote:

>Back about 4 decades when I tried my hand at TV repair, me and the guys
>I worked with had to replace a lot of what were called
>"glowbars/globars", they were actually PTC devices hooked to the
>degaussing coil around the CRT of a TV set to power the degaussing coil
>for a short period every time a TV set was turned on.

That type of thermistor works backwards from the flavor I'm proposing.
For the degaussing coil, the thermistor has a low resistance when
cold. When it gets warm, the resistance increases dramatically. When
installed in series with the degaussing coil, it allows an initial
blast of current through the coil, followed by effectively turning
itself off.

In the case of protecting the thermal fuse, it's the other way around.
When cold, the thermistor has a fairly high resistance, thus limiting
the peak inrush current. As the current heats up the thermistor, the
resistance decreases, allowing the device to operate normally.

>The only problem would be
>coming up with a thermistor that could handle the current of the heating
>element when it's connected in series with it.

It's not current handling but rather energy handling capacity. If the
inrush current surge lasts too long, the thermistor will get rather
hot. If this were a design exercise, I would need the steady state
current, the peak inrush current, and the approximate time duration in
order to calculate the energy dissipated (in joules or watt-seconds)
and eventually the maximum thermistor resistance.

[The Daring Dufas]

That's why I thought an indirect approach might work and last longer. ^_^

TDD

[k...@att.bizzzzzzzzzzzz]

On Mon, 26 Mar 2012 00:13:49 -0700, Jeff Liebermann <je...@cruzio.com> wrote:

>On Mon, 26 Mar 2012 00:53:26 -0500, The Daring Dufas
><the-dari...@stinky.net> wrote:
>
>>Back about 4 decades when I tried my hand at TV repair, me and the guys
>>I worked with had to replace a lot of what were called
>>"glowbars/globars", they were actually PTC devices hooked to the
>>degaussing coil around the CRT of a TV set to power the degaussing coil
>>for a short period every time a TV set was turned on.
>
>That type of thermistor works backwards from the flavor I'm proposing.
>For the degaussing coil, the thermistor has a low resistance when
>cold. When it gets warm, the resistance increases dramatically. When
>installed in series with the degaussing coil, it allows an initial
>blast of current through the coil, followed by effectively turning
>itself off.

That's a PTC (positive temperature coefficient) thermistor. Its resistance
goes up with temperature.

>In the case of protecting the thermal fuse, it's the other way around.
>When cold, the thermistor has a fairly high resistance, thus limiting
>the peak inrush current. As the current heats up the thermistor, the
>resistance decreases, allowing the device to operate normally.

Nope. A PTC protection device (a.k.a. "polyfuse" or "polyswitch") is also a
PTC device. It has very low resistance when cold. When excessive current
flows through it, it heats and becomes open, more or less. It's only reset
when the voltage is taken off and it's allowed to cool. It wouldn't work if
it had a high resistance when it was cold.

Both devices are PTC thermistors, albeit with different characteristics. NTC
thermistors are normally used as temperature sensors.

>>The only problem would be
>>coming up with a thermistor that could handle the current of the heating
>>element when it's connected in series with it.
>
>It's not current handling but rather energy handling capacity. If the
>inrush current surge lasts too long, the thermistor will get rather
>hot. If this were a design exercise, I would need the steady state
>current, the peak inrush current, and the approximate time duration in
>order to calculate the energy dissipated (in joules or watt-seconds)
>and eventually the maximum thermistor resistance.

Any sane person would just buy the one designed for the application.

[bob haller]

the machines are roll laminators that put plastic on paper, think of
menus, often they are laminated.

the high inrush current leads to all sorts of troubles, with burned
out switches, fried connectors, burned out boards etc..

[k...@att.bizzzzzzzzzzzz]

That may be true, but what does it have to do with the price of eggs in China?

[Jeff Liebermann]

On Mon, 26 Mar 2012 06:53:12 -0700 (PDT), bob haller <hal...@aol.com>
wrote:

>the machines are roll laminators that put plastic on paper, think of
>menus, often they are laminated.

One of these?
<http://www.ledcolaminator.com>
I do computah work for a print shop that has several of these. I
don't recall hearing about any thermal fuse failures.

>the high inrush current leads to all sorts of troubles, with burned
>out switches, fried connectors, burned out boards etc..

Do you have any specs or measurements for one of these machines?
1. Operating voltage:
2. Peak inrush current:
3. Steady state current:
4. Duration of inrush surge:
If you want, I can then grind the numbers and offer a recommended
thermistor. I have that horrible feeling that the power consumption
may be high enough that a suitable inrush thermistor might not work
(or exist).

[Sjouke Burry]

The Daring Dufas <the-dari...@stinky.net> wrote in news:jkf3na$uvu$1
@dont-email.me:

> On 3/21/2012 11:03 PM, jeff_wisnia wrote:
>> Over the years I've had a few thermal fuses in houshold appliances go
>> open for no apparent reason. When I've replaced them with ones with
the
>> same temperature rating they stayed working fine for years more.
>>
>> A couple of days ago our three year old Bunn coffee maker quit,
because
>> a 141 degree celcius overtemperature thermal fuse on the water tank
>> opened. It might possibly have happened because the water tank
>> thermostat stuck closed, but after I repaired it the thermostat cycled
>> just as it should.
>>
>> I was suprised to find that there were TWO identical thermal fuses
>> connected in series located right next to each other, the bodies were
>> actually touching. That seemed like a belt and suspenders approach,
>> unless there's a significant likelihood that a thermal fuse won't open
>> when it should?
>>
>> Comments?
>>
>> Thanks guys,
>>
>> Jeff
>>
>>
>
> I could understand parallel fuses because one may not handle the
> current. Perhaps in series it's safer because the unit will shut
> off if one fails to open? o_O
>
> TDD
>
That is because they dont trigger on current(mainly).
They trigger when their surrondings get to hot.
Imagine a current carrying spring, soldered to the other
side with solder of a particural melting temperature.
Of course you can also heat them by massive overload in
current, but that is not the way they ought to work.

[Carolee]

On 03/23/12 22:02, Michael A. Terrell wrote:
>
> N_Cook wrote:
>>
>> Michael A. Terrell<mike.t...@earthlink.net> wrote in message
>> news:OeGdncrMOvJ61_HS...@earthlink.com...
>>>
>>> N_Cook wrote:
>>>>
>>>> Perhaps the voltage rating was lower than the required use, ie in fused
>>>> state not rated for the service voltage across the broken section so
>> someone
>>>> thought, I know , we'll put 2 in series ;-)
>>>
>>>
>>> Which would do nothing, if they couldnn't handle the voltage.
>>>
>>> Have you ever looked at the wiring in a furnace? They use multple
>>> thermal shutdowns, for liability in the US.
>>
>> so you have no visual sense for emoticons
>
>
> I did too many fire restoration jobs after a pair of switches failed
> and people died. I see no humor in people dying from failed and jury
> rigged repairs. Laugh all you want. It fits you.
>
>

I see humor in you dying from sodomizing an 8 year old girl, pencil dick.