Todays Puzzler.The mystery of electricity

[j]

The spare bath in my house was added in the '60s. There is a fixture
over the sink with a double light socket, one faces left and one faces
right,it's one piece. Common at one time.

So today I wanted to put a fan in this otherwise unused bathroom. I got
an edison base adapter and screwed it in one of the sockets. Plugged in
the fan and nothing. Didn't matter how it was switched. So I went off to
get a bulb to test the other socket. When I screw in the bulb, it does
not light but the fan goes on. The fan seems to be fine and the bulb is
completely dark. Unscrew the bulb and the fan turns off.

WTF!

Who cares to gamble a wild ass guess?

Obviously the fixture has to go! But very strange.

Jeff

[Bob F]

Maybe you have a 220V circuit with 2 110V bulbs wired in series.

[Jim Wilkins]

"j" <mun...@att.net> wrote in message
news:jq8itp$oj0$1...@news.albasani.net...

Maybe the torque on the bulb wiggles a poor connection.

jsw

[Winston]

Bob F wrote:
> j wrote:

(...)

>> Who cares to gamble a wild ass guess?
>>
>> Obviously the fixture has to go! But very strange.
>>
>
> Maybe you have a 220V circuit with 2 110V bulbs wired in series.

I concur with your diagnosis, Dr.

Except that the 'cold' resistance of an incandescent
bulb would pass plenty of current to power a series-
connected fan in a ~120 V circuit.

--Winston

[Bob F]

Which is what he said it does.

[amdx]

That's also my guess, when the bulb is screwed in it compresses
a connection in the socket.
Mikek

[Gary Heston]

Sounds like the sockets are in series, but hooked to a 120V circuit--if
it was a 220V/240V circuit, it'd probably smoke the fan.

The fixture is probably ok, just miswired. I gather you haven't been
using it, since you had to fetch a bulb for testing.

I suppose it may have been miswired on purpose--to provide softer light,
particularly for late night visits.


Gary


--
Gary Heston ghe...@hiwaay.net http://www.thebreastcancersite.com/

"Politics is the art of looking for trouble, finding it everywhere,
diagnosing it incorrectly and applying the wrong remedies." Groucho Marx

[Vaughn]

On 5/31/2012 8:35 PM, Gary Heston wrote:
> The fixture is probably ok, just miswired. I gather you haven't been
> using it, since you had to fetch a bulb for testing.
>
> I suppose it may have been miswired on purpose--to provide softer light,
> particularly for late night visits.

The above explanation sounds more likely than the 240-volt guess.

I also like soft light in a bathroom. I choose slow-starting CFLs these
days. Guys shouldn't try to pee in the dark, but full-bright light is
piercing when you get up in the middle of the night.

Vaughn

[Winston]

Bob F wrote:
> Winston wrote:

(...)

>> Except that the 'cold' resistance of an incandescent
>> bulb would pass plenty of current to power a series-
>> connected fan in a ~120 V circuit.
>>
>
> Which is what he said it does.

Yup. As Gary Heston points out, the series connection
might have been on purpose.

--Winston

[Jim Wilkins]

"Winston" <Win...@Bigbrother.net> wrote in message
news:jq9op...@news4.newsguy.com...

Easily checked with two bulbs of different wattage.

jsw

[Winston]

Jim Wilkins wrote:
> "Winston"<Win...@Bigbrother.net> wrote in message
> news:jq9op...@news4.newsguy.com...
>> Bob F wrote:

(...)

>>> Which is what he said it does.
>>
>> Yup. As Gary Heston points out, the series connection
>> might have been on purpose.
>>
>> --Winston
>
> Easily checked with two bulbs of different wattage.

Yup.

Though, personally I'd want to shut off the supply and
open the fixture box to determine what other surprises
lay in wait. :)

--Winston

[j]

On 5/31/2012 4:06 PM, j wrote:

I took apart the fixture today and found out why. Let's review the
evidence:

> The spare bath in my house was added in the '60s. There is a fixture
> over the sink with a double light socket, one faces left and one faces
> right,it's one piece.

Note the "one piece".

>
Common at one time.
>
> So today I wanted to put a fan in this otherwise unused bathroom. I got
> an edison base adapter and screwed it in one of the sockets. Plugged in
> the fan and nothing. Didn't matter how it was switched. So I went off to
> get a bulb to test the other socket. When I screw in the bulb, it does
> not light but the fan goes on. The fan seems to be fine and the bulb is
> completely dark.

Note that the fan worked fine, it's not that it struggled on partial
voltage, and if it was wired in series, the bulb (an incandescent) was
completely dark.

This removes the series connection theories. And certainly the 220v
theory that depended on it.

So, what we have in the socket in the dead middle is a U shaped flat
copper strip. The hot wire is soldered to this and each end of the U
contacts a bulb center contact. For the ground threaded part: there are
two of these with a solder tab. They are facing outward, of course, but
the tabs are together and the ground wire is soldered to the left socket
that had the bulb screwed in. The tabs are in turn soldered to each other.

So, what happened?

The connection between the two tabs broke apart. When the bulb was
screwed in it pushed it's ground tab out enough to contact the other tab
and send power through it's "ground" connection.

The winner is: Jim Wilkins

Why didn't the bulb light? The "hot" contact was oxidized enough to be
an insulator.


I have pics and video...

Jeff

[Winston]

j wrote:
> On 5/31/2012 4:06 PM, j wrote:
>
> I took apart the fixture today and found out why.

Thanks for closing the loop, j.
Well done, Jim.

--Winston

[Brian Gaff]

Sounds like someone has done my favourite trick to make bulbs last
indefinitely and put them in series.
Brian

--
From the Bed of Brian Gaff.
The email is valid as bri...@blueyonder.co.uk
Blind user.

"j" <mun...@att.net> wrote in message
news:jq8itp$oj0$1...@news.albasani.net...

[Jim Wilkins]

"j" <mun...@att.net> wrote in message

news:jqautc$2sd$1...@news.albasani.net...
> ...> The connection between the two tabs broke apart. When the bulb

> was screwed in it pushed it's ground tab out enough to contact the
> other tab and send power through it's "ground" connection.
>

Bad grounds and intermittent connections cause the oddest symptoms.

In Army Signal Corps electronic school the instructors doctored AGC
glass fuses to remind us to check them with a meter, not just by
sight. They heated one end cap to melt the glue and pop off the cap,
then inserted too-short heavy bus wire and even blue ("the fuse blew")
paper to make it look good again. I caught the 1 Amp fuse with 12 AWG
wire inside it visually and went up to joke with the instructor about
it, then we watched most of the class pull out the phony fuses, give
them a puzzled look, put them back and continue troubleshooting.

jsw

[m II]

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Jim Wilkins wrote:

> Bad grounds and intermittent connections cause the oddest
> symptoms.
>
> In Army Signal Corps electronic school the instructors doctored AGC
> glass fuses to remind us to check them with a meter, not just by
> sight. They heated one end cap to melt the glue and pop off the
> cap, then inserted too-short heavy bus wire and even blue ("the
> fuse blew") paper to make it look good again. I caught the 1 Amp
> fuse with 12 AWG wire inside it visually and went up to joke with
> the instructor about it, then we watched most of the class pull out
> the phony fuses, give them a puzzled look, put them back and
> continue troubleshooting.

Fuses on electric stoves/ranges are bad for that. They commonly break
the link where it bends, just outside of sight. The fuse looks good
through the glass, but there's no continuity.

The repeated cycling off/on and the resultant thermally caused
expansion/contraction probably work hardens the metal where it's
already been stressed by the bend, causing the fractures.

So, yes...using a meter is a very good idea.


mike






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[j]

On 6/1/2012 8:56 PM, Jim Wilkins wrote:
> "j"<mun...@att.net> wrote in message
> news:jqautc$2sd$1...@news.albasani.net...
>> ...> The connection between the two tabs broke apart. When the bulb
>> was screwed in it pushed it's ground tab out enough to contact the
>> other tab and send power through it's "ground" connection.
>>
>
> Bad grounds and intermittent connections cause the oddest symptoms.

They do indeed.

> In Army Signal Corps electronic school the instructors doctored AGC
> glass fuses to remind us to check them with a meter, not just by
> sight. They heated one end cap to melt the glue and pop off the cap,
> then inserted too-short heavy bus wire and even blue ("the fuse blew")
> paper to make it look good again.

Nice trick on their part. As you know, it's not unusual to get a bad
joint in the fuse end caps.

I caught the 1 Amp fuse with 12 AWG
> wire inside it visually and went up to joke with the instructor about
> it, then we watched most of the class pull out the phony fuses, give
> them a puzzled look, put them back and continue troubleshooting.

People make a lot of assumptions that they could simply check out
instead. Often leads to wasted time and money.

I knew this was a bad connection somewhere. As it turns out, two bad
connections.

Jeff
>
> jsw
>
>

[Vaughn]

On 6/1/2012 8:56 PM, Jim Wilkins wrote:

> Bad grounds and intermittent connections cause the oddest symptoms.
>

Yes, I learned the hard way. Early in my career, I spent two days
trying to troubleshoot a simple problem with the tail lights on a pickup
truck. They had the oddest symptoms! My meter seemed to be of no help,
giving all kinds of strange readings. In the end, it totally defeated me!

In desperation I took the truck to a dealer. They said "No problem!"
When I got it back, I discovered that they had installed a ground wire
between two certain frame members under the truck, which totally cleared
up the problem. They had probably seen dozens with the exact same issue.

Vaughn

[bob haller]

attention, the new fan should really be on a GFCI circuit. Which
doesnt sound like it is from the OPs description.....

Incidently I replaced all the wiring on a trailer, and had never done
anything like it before. I had my friends box trailer in my driveway
for a few days. I completed the rewire and was very proud when she
came to pick it up.... only problem the lights didnt work.....


traced to a bad ground wire in her nearly new ford commecial van.....

i leared a lot fom that volunteer job....

[j]

On 6/2/2012 11:49 AM, bob haller wrote:
> attention, the new fan should really be on a GFCI circuit. Which
> doesnt sound like it is from the OPs description.....

It is now. It's an unused bathroom with the water off. I wanted a fan in
the window and there are no outlets. I ran an extension over to a
kitchen outlet.

>
> Incidently I replaced all the wiring on a trailer, and had never done
> anything like it before. I had my friends box trailer in my driveway
> for a few days. I completed the rewire and was very proud when she
> came to pick it up.... only problem the lights didnt work.....
>
>
> traced to a bad ground wire in her nearly new ford commecial van.....
>
> i leared a lot fom that volunteer job....

I was in the audio biz at one time and grounds are all important.

As far as vehicles, grounds are always suspect.

If you clip your volt meter on to a known good ground, and have
everything "on", then you should have near zero volts at other grounds
you test.

It's easier/faster to test volts than resistance. Testing resistance
when you have clear suspects.

Of course, common problems become known after a while. But, I'm at
the stage in my life that I never want to have the same problem more
than once.

Jeff

[Vaughn]

On 6/2/2012 1:15 PM, j wrote:
> If you clip your volt meter on to a known good ground, and have
> everything "on", then you should have near zero volts at other grounds
> you test.
>
> It's easier/faster to test volts than resistance.

Yep! That's exactly what I do. I've found zillions of bad connections
with a voltmeter. It's just a simple application of Ohm's law.

Vaughn

[Mho]

Stick with your failed Internet business.

------------
"m II" wrote in message news:jqc0qq$nrt$1...@dont-email.me...

[Ralph Mowery]

"Jim Wilkins" <murat...@gmail.com> wrote in message .

>
> In Army Signal Corps electronic school the instructors doctored AGC glass
> fuses to remind us to check them with a meter, not just by sight. They
> heated one end cap to melt the glue and pop off the cap, then inserted
> too-short heavy bus wire and even blue ("the fuse blew") paper to make it
> look good again. I caught the 1 Amp fuse with 12 AWG wire inside it
> visually and went up to joke with the instructor about it, then we watched
> most of the class pull out the phony fuses, give them a puzzled look, put
> them back and continue troubleshooting.
>
> jsw

Also check the new fuse before putting it back in. I have seen lots of new
fuses that are bad. I opened a new box that had about a dozen high dollar
fuses (something like 100 amp bolt in fuses) and over half of them were
open.

[The Real Bev]

On 06/02/2012 08:24 PM, Ralph Mowery wrote:

> "Jim Wilkins"<murat...@gmail.com> wrote in message .
>>
>> In Army Signal Corps electronic school the instructors doctored AGC glass

When did 3AG fuses become AGC? Serious question...

--
Cheers, Bev
"This software is as user-friendly as a cornered rat!"

[Jim Wilkins]

"The Real Bev" <bashl...@gmail.com> wrote in message
news:jqesld$ajr$1...@dont-email.me...

3AG is one of several sizes within the AGC classification.
http://www.jaycar.com.au/images_uploaded/fuseprmr.pdf

jsw

[Jim Wilkins]

"Ralph Mowery" <rmower...@earthlink.net> wrote in message

>
> Also check the new fuse before putting it back in. I have seen lots
> of new fuses that are bad. I opened a new box that had about a
> dozen high dollar fuses (something like 100 amp bolt in fuses) and
> over half of them were open.

But sir, the production test station showed they were good, when I
pushed the red button the meter stopped at 100A just like it's
supposed to!

jsw

[j]

Never knew that. The "AG" originally stood for "Automotive glass"
whether in 3AG 1 or AGC 1.

In fact the 3AG is the old commercial designation (and old military) and
the AGC is the new commercial:

http://www.tpub.com/neets/book3/8e.htm

The fuse definitions are identical in this case: a "3AG 1" is an "AGC 1"

At any rate we are unlikely to see these fuses in modern equipment as
automotive is all spades and most home electronics is the smaller GMA.

Jeff
>
> jsw
>
>

[Jim Wilkins]

"j" <mun...@att.net> wrote in message

news:jqfmv8$s3q$1...@news.albasani.net...
> ...

> At any rate we are unlikely to see these fuses in modern equipment
> as automotive is all spades and most home electronics is the smaller
> GMA.
>
> Jeff

My most recent home entertainment electronics purchase was a
1971-style HP RF Spectrum Analyzer.

BTW, the VLC player v2.0.1 has a .wtv codec and can now play back HDTV
recorded with 7 Media Center on an XP machine.

jsw

[Mho]

I use xbmc, free and it plays everything without any codec or what-not
add-ons needed.

----------

"Jim Wilkins" wrote in message news:jqgdg5$laf$1...@dont-email.me...

[Mho]

Yeah, current limitin' fuses, jus' like they all tell ya'.

----------
"Jim Wilkins" wrote in message news:jqf2pr$4uq$1...@dont-email.me...

But sir, the production test station showed they were good, when I
pushed the red button the meter stopped at 100A just like it's
supposed to!

jsw

------------

[Jim Wilkins]

"Mho" <Impe...@UgotOCD.invalid> wrote in message
news:iqzzr.21159$FL5....@newsfe03.iad...

> Yeah, current limitin' fuses, jus' like they all tell ya'.
>
> ----------
> "Jim Wilkins" wrote in message news:jqf2pr$4uq$1...@dont-email.me...
> But sir, the production test station showed they were good, when I
> pushed the red button the meter stopped at 100A just like it's
> supposed to!
> jsw

The people hired to operate production line test stations typically
know so little of electronics that it's really hard to guess what they
might assume. I designed what I thought was a UAW-proof control panel
for a machine for GM, then watched the operator whose nose remained
buried in a book swat blindly at the buttons until she heard the fans
turn on.

jsw

[z]

j <mun...@att.net> wrote in news:jqdhlk$flp$1...@news.albasani.net:

>>
>> traced to a bad ground wire in her nearly new ford commecial van.....
>>
>> i leared a lot fom that volunteer job....
>
> I was in the audio biz at one time and grounds are all important.
>
> As far as vehicles, grounds are always suspect.
>

Heh.. the instrument cluster ground was bad in my old bmw .. when you
cranked the stereo the gas gauge would jump in time with the beat :)

[Mho]

First Color Organ? Did you get it to trigger the low fuel lamp?

---------
"z" wrote in message news:XnsA0807B0D8...@216.196.97.131...