lights go dim when kettle switches on

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Ben

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Jun 3, 2007, 2:35:42 PM6/3/07
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We recently moved to a new house (built in the 40's with an annexe added
in the 80s). The lights go dim when anything with high current drain
like a kettle or electric shower is turned on. This works for all
different combinations of ceiling lights and lights plugged into sockets
in the house and the annexe, and happens when any high-current appliance
is switched on in the house or the annexe (which are on different
fuseboxes). This would suggest to me that the voltage is dropping at the
point where the mains enters the house, and therefore that the cable
coming up from the road is under rated. Does this sound like a
reasonable conclusion, and is it something we should worry about?

meow...@care2.com

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Jun 3, 2007, 3:14:37 PM6/3/07
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If the dimming is significant, as appears to be from what you say,
then youre looking at an immediate fire risk.


NT

John Rumm

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Jun 3, 2007, 4:15:57 PM6/3/07
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Ben wrote:

This is difficult to quantify without numbers. Some dimming is to be
expected, but it depends on how much you are getting.

If you connect a voltmeter to the system and take a reading what do you
get? What does it change to when you add say a 3kW load from the kettle?

Try and place the voltmeter on a different circuit to the one you are
running the test load on. That way you should have your results
influenced less by the resistance of the houses wiring.


--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

Stephen Dawson

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Jun 3, 2007, 4:26:24 PM6/3/07
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"John Rumm" <see.my.s...@nowhere.null> wrote in message
news:46632194$0$8738$ed26...@ptn-nntp-reader02.plus.net...

Don't mess about with this, phone your electricity supplier and ask for an
emergency call as you may have a fault with the cutout or meter. If they
can't find anything wrong then ask for a recording voltmeter to be fitted.


--
Regards

Stephen Dawson
Fox Electrical Services Ltd
www.foxelectrical.co.uk


meow...@care2.com

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Jun 3, 2007, 4:48:55 PM6/3/07
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On 3 Jun, 21:26, "Stephen Dawson" <stephendaw...@ntlworld.com> wrote:
> "John Rumm" <see.my.signat...@nowhere.null> wrote in message

what needs the most urgent checking is the wiring within the house,
and a recording meter at the incomer will only check a small fraction
of that.

But really, if the dimming is significant, then theres no need for a
voltmeter, the problem is serious.


NT

tony sayer

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Jun 3, 2007, 5:19:21 PM6/3/07
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In article <46630a02$0$8741$ed26...@ptn-nntp-reader02.plus.net>, Ben
<nos...@nospam.com> writes

I'd expect "some" dimming when the shower is on as they take silly
amounts of current, the kettle less so. It seems as if the voltage drop
across the cables is too great but that can be checked with a voltmeter
to see if its excessive or not. It could be possible that there is a
high resistance joint somewhere thats causing the voltage drop and that
can be a fire risk if it gets too hot!..

As you say it does seem that the problem might be on the supply side
can't remember of the top of my head but its something like plus 6 % and
minus 10% of 230 volts to be within tolerance.

Are you on an overhead or underground supply?..

Best bet is to have a competent electrician check it out......
--
Tony Sayer

Ed Sirett

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Jun 3, 2007, 5:33:47 PM6/3/07
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If the dimming is such that you could say whether he kettle is on or not
just by looking at the lights then there is a big problem.
There is a high resistance on the incomer, meter connections, main switch,
or main switch connections.

Measure the line neutral voltage if there is a drop of more than 10V when
the kettle is used then there is a potential problem.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs here: http://www.makewrite.demon.co.uk/GasFittingStandards

The Natural Philosopher

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Jun 3, 2007, 5:56:52 PM6/3/07
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In my case it was not e cable: It was the trasformer up a pole..that was
the size of a small Tv set.

I now have my very own substation, the size of a dog kennel for a
reasonably large dog.

Which appears to have left its genitalia inside, or at least the whole
installtion is now the dogs knackers.

The Natural Philosopher

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Jun 3, 2007, 5:57:31 PM6/3/07
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Yawn. Here we ho again. More bollocks from the wannabee Drivel man.

The Natural Philosopher

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Jun 3, 2007, 5:59:56 PM6/3/07
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Absolute crap. Its patently obvious from his post that the issue lies
outside the house.

It happens on every combination of devices on all circuits.

Its almost certainly either the incoming wires from the local
substation, or, if its a personal transformer on a pole as mine was, that.

John Rumm

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Jun 3, 2007, 6:10:46 PM6/3/07
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meow...@care2.com wrote:

> what needs the most urgent checking is the wiring within the house,
> and a recording meter at the incomer will only check a small fraction
> of that.

The fault as described does not really point to a house wiring fault -
the same results are observed on two CUs and all circuits regardless of
where the load is. This points to a fault at the incomer, or in the supply.

js...@ntlworld.com

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Jun 3, 2007, 7:37:45 PM6/3/07
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The harmonised EU nominal supply voltage is 230V +10% -6%.


If lights merely dim *briefly* under heavy load *switching on*,
this is not uncommon with high loads (13A, 40-50A shower).
It more commonly noticed with large welding equipment.

If lights dim *continually* under heavy load *operation*,
that indicates a **serious** defect requiring investigation.

Cause may be house-side (high resistance CU busbars
due to bad connections, oxidised, corroded) or utility-side
(high resistance meter/service-head/overhead connections).
Overheating service heads do cause uncontainable fires.
--
JS-B.

The Wanderer

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Jun 4, 2007, 3:25:37 AM6/4/07
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On Sun, 03 Jun 2007 19:35:42 +0100, Ben wrote:

You need to satisfy yourself that everything is OK around the meter
position for a first off. If you get someone to switch on the shower -
that'll take the most - and just have a listen and a sniff around the meter
position and the consumer units, that should tell you pretty quickly if you
have a loose connection somewhere abouts. You'll get some arcing and/or
buzzing.

Are you in a rural or urban location? Sounds very much like a problem with
the distribution network that supplies your property. This can quite often
be a real problem in rural areas, where distribution networks can be like
wet string, particularly where there hasn't been much development for a few
years.

Contact the local distribution company - they may not neccesarily be the
company who sell you your electricity - and tell them you have a problem
with the lights dipping whenever you put any load on. Probably be a two
stage thing, first they'll get a linesman out to check connections on the
system (presuming it's overhead) then if they don't find anything, they'll
probabaly instal a recording voltmeter for a few days, which will quantify
the problem.

Be warned, however, post privatisation, they'll probably try to make you
pay for any improvements they have to make to their system. In general
terms you shouldn't, but come back for more advice if they try it on.

--
the dot wanderer at tesco dot net

The Wanderer

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Jun 4, 2007, 3:26:50 AM6/4/07
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How do you come to that conclusion?

Ben

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Jun 4, 2007, 12:02:22 PM6/4/07
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The Wanderer wrote:
> Are you in a rural or urban location? Sounds very much like a problem with
> the distribution network that supplies your property. This can quite often
> be a real problem in rural areas, where distribution networks can be like
> wet string, particularly where there hasn't been much development for a few
> years.

Its very much a rural area, and to answer a question from another post
the dimming is continuous until the heavy load is switched off. I'll
measure the voltage drop and if its excessive report it to the
distribution company (and report back here of course).

The Wanderer

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Jun 4, 2007, 12:19:39 PM6/4/07
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Just remember that cheap MMs are really only an indication at best. Back in
the days when I used to have to check voltages I carried a (very expensive)
laboratory substandard that was checked annually against a national
standard. Not unknown for DMMs or cheap analogue MMs to read as much as
10-15volts different to the SS! Indeed, I also had (and still have,
somewhere) an Avo8 that read different to the SS. And it had been for
recalibration five or six times over the years. :-(

tom.ha...@gmail.com

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Jun 4, 2007, 12:56:48 PM6/4/07
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Recently, during the renovation of my house, I found that all my
wiring was jammed through a hole in a wooden beam. I had to reroute it
to do some work there (a full rewire is immanent). When I finally
managed to extricate the various circuits from the hole ( I have no
idea how they got them in there), there were clear signs of
overheating. After connecting everything back up, my lights were
definitely brighter, and my kettle boils quicker too.

I wouldn't rule out a problem in your house until you've made sure
that your circuits are as they should be. In my house half the
bathroom wiring was spurred of the cooker circuit. If your supply is
affected by a kettle, you must be extremely remote.

Regards

T

Ben

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Jun 4, 2007, 1:07:08 PM6/4/07
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tom.ha...@gmail.com wrote:
> I wouldn't rule out a problem in your house until you've made sure
> that your circuits are as they should be. In my house half the
> bathroom wiring was spurred of the cooker circuit. If your supply is
> affected by a kettle, you must be extremely remote.

The thing is, any light (ceiling or socket, house or annexe) dims, and
the house and annexe are on different fuseboxes, so I reckon the voltage
has to drop at the point where the mains enters the house.

Ben

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Jun 4, 2007, 1:13:00 PM6/4/07
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tony sayer wrote:
> Are you on an overhead or underground supply?..

It appears to be overhead as far as the bottom of the driveway and then
underground up the front garden.

Dave Fawthrop

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Jun 4, 2007, 2:22:14 PM6/4/07
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On Mon, 04 Jun 2007 18:13:00 +0100, Ben <nos...@nospam.com> wrote:

|!tony sayer wrote:
|!> Are you on an overhead or underground supply?..
|!
|!It appears to be overhead as far as the bottom of the driveway and then
|!underground up the front garden.

Have you complained to whoever looks after the distribution of electricity
in your area? **Not** who you pay, they are different. Being overhead
there may be a problem with the supply to the house.
--
Dave Fawthrop <sf hyphenologist.co.uk> 165 *Free* SF ebooks.
165 Sci Fi books on CDROM, from Project Gutenberg
http://www.gutenberg.org/wiki/Main_Page Completely Free to any
address in the UK. Contact me on the *above* email address.

Stephen Dawson

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Jun 4, 2007, 2:58:04 PM6/4/07
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<meow...@care2.com> wrote in message
news:1180903735.4...@k79g2000hse.googlegroups.com...

NT,

Stand back from this and leave it to those that have the experience in this
field, i.e. me. (10 years investigating voltage compliants for an REC, then
10 years running my own electrical firm.)

Stephen Dawson

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Jun 4, 2007, 3:01:26 PM6/4/07
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"Ben" <nos...@nospam.com> wrote in message
news:466446b4$0$8753$ed26...@ptn-nntp-reader02.plus.net...

Ben,

Take some free and very good advice, ring your local electricity company,
and get them out as soon as possible. You may save yourself a lot of grief.

The Natural Philosopher

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Jun 4, 2007, 3:22:08 PM6/4/07
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any sign of a pole mounted transformer?

Or is it two thick wires up that pole?


In either case, contact supply company.

The Natural Philosopher

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Jun 4, 2007, 3:20:22 PM6/4/07
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How does the power come in? overhead from a pole mounted transformer? or
underground?.

If the former, get the leccy company to get you a better one.

Ben

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Jun 4, 2007, 3:42:08 PM6/4/07
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The Natural Philosopher wrote:
> any sign of a pole mounted transformer?
>
> Or is it two thick wires up that pole?

Its two thick wires, all the way up the road from the village.

The Natural Philosopher

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Jun 4, 2007, 4:18:46 PM6/4/07
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Mm. Need to have THICKER ones then ;-)

Doctor Drivel

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Jun 4, 2007, 4:53:05 PM6/4/07
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"Ben" <nos...@nospam.com> wrote in message
news:46646b08$0$8719$ed26...@ptn-nntp-reader02.plus.net...

Can't you move the village closer?

tom.ha...@gmail.com

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Jun 4, 2007, 5:56:53 PM6/4/07
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On 4 Jun, 18:07, Ben <nos...@nospam.com> wrote:

If I were you, I would check that all your circuits are in good order.
Does removing your fuses disable the circuits in your house as you
expect? Do the fuse wires look correct? Sometimes second fuse boxes
are just wired like any other final circuit (I have two of those)
sometimes off similar meter tails (I have one of those) and sometimes
off reduced meter tails (I have one of those too).

The symptoms you describe do seem to indicate a supply problem, but I
find that hard to believe unless you are extremely remote. I and two
neighboring houses are supplied by the same 25mmish overhead cable. It
attaches to my house, then splits into 3. I can't tell if they are
boiling a kettle.

T

tony sayer

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Jun 4, 2007, 6:01:24 PM6/4/07
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In article <46644814$0$8737$ed26...@ptn-nntp-reader02.plus.net>, Ben
<nos...@nospam.com> writes

Always seems that overhead has less capacity then what underground does.

Theres a place near here that has Five subs off the same piddly little
transformer and the furthest one on the line is some 500 odd yards!..

But he isn't bothered .. as he'd be using candles if he had his way;!..
--
Tony Sayer

Peter Lynch

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Jun 4, 2007, 6:45:07 PM6/4/07
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I wouldn't say it's a problem, necessarily, just that the cable to his
house is a particularly long run. At a friends place (way out in the
boonies) I've measured a 12V drop when her 2kW kettle is plugged in.
Worse, the UPS starts running when the fridge kicks in.
Yes the lights do go dim, mo it's not a problem - just the way of things.

Pete

--
..........................................................................
. never trust a man who, when left alone ...... Pete Lynch .
. in a room with a tea cosy ...... Marlow, England .
. doesn't try it on (Billy Connolly) .....................................

meow...@care2.com

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Jun 4, 2007, 6:50:44 PM6/4/07
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On 4 Jun, 08:26, The Wanderer <m...@privacy.net> wrote:

> On Sun, 03 Jun 2007 12:14:37 -0700, meow2...@care2.com wrote:

> > If the dimming is significant, as appears to be from what you say,
> > then youre looking at an immediate fire risk.
>
> How do you come to that conclusion?

through being tired I think!

NT

meow...@care2.com

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Jun 4, 2007, 7:00:55 PM6/4/07
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Thats what I was wondering initially, a dogs dinner of a wiring job,
but with it being a remote property I guess an old underrated
transformer o overhead wire would be more likely.


NT

John Rumm

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Jun 4, 2007, 7:04:57 PM6/4/07
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Peter Lynch wrote:

> I wouldn't say it's a problem, necessarily, just that the cable to his
> house is a particularly long run. At a friends place (way out in the
> boonies) I've measured a 12V drop when her 2kW kettle is plugged in.
> Worse, the UPS starts running when the fridge kicks in.
> Yes the lights do go dim, mo it's not a problem - just the way of things.

That would suggest a supply impedance of something like 1.5 ohms. Which
if true, certainly could be a problem for things powered by induction
motors (like fridges) since it would mean that they are drawing over
their rated current and dissipating more heat in the motor windings.
There is also the danger that motors can stall under load at startup
(undervoltage can reduce the already limited starting torque).

The Wanderer

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Jun 5, 2007, 2:58:16 AM6/5/07
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Ben, you've had two or three people who either work in or used to work in
the supply industry tell you to contact your local distribution company,
because in their opinion it's a problem with the distribution network.

You've also had quite a few others who all have their own pet theories
coming up with all sorts of red herrings.

I know what I'd already have done.

meow...@care2.com

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Jun 5, 2007, 3:51:50 AM6/5/07
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On 4 Jun, 19:58, "Stephen Dawson" <stephendaw...@ntlworld.com> wrote:
> <meow2...@care2.com> wrote in message
news:1180903735.4...@k79g2000hse.googlegroups.com...

> NT,


>
> Stand back from this and leave it to those that have the experience in this
> field, i.e. me. (10 years investigating voltage compliants for an REC, then
> 10 years running my own electrical firm.)

I can understand pointing out that I was half asleep at the time, but
these kind of comments seem a little off beam.


NT

Ian White

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Jun 5, 2007, 3:52:20 AM6/5/07
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John Rumm wrote:
>Peter Lynch wrote:
>
>> I wouldn't say it's a problem, necessarily, just that the cable to his
>> house is a particularly long run. At a friends place (way out in the
>> boonies) I've measured a 12V drop when her 2kW kettle is plugged in.
>> Worse, the UPS starts running when the fridge kicks in.
>> Yes the lights do go dim, mo it's not a problem - just the way of things.
>
>That would suggest a supply impedance of something like 1.5 ohms. Which
>if true, certainly could be a problem for things powered by induction
>motors (like fridges) since it would mean that they are drawing over
>their rated current and dissipating more heat in the motor windings.
>There is also the danger that motors can stall under load at startup
>(undervoltage can reduce the already limited starting torque).
>
In practice it's nothing like that bad. We live in such a house, a
former farm cottage with a long underground (private) supply from the
farm. The farm buildings have a direct drop from 11kV, but the cable to
the cottages was laid at a time when farm workers were lucky to have
electric light at all, and a 5A socket in every room was sheer luxury.
In other words, by modern standards the cable is well undersized.

I keep a calibrated RMS meter on the supply all the time, and off-load
we see 250V, which is fine. There is a 10V drop when a kettle is
switched on, and ordinary incandescent bulbs can be seen to dim a
little. However, most of the lighting is by CFLs and fluorescents,
which are much less sensitive.

The slight flickering of the lights is the only practical problem.
There's a lot of electronics in this house, a couple of UPSes, several
induction motors up to about 1.5kW, and some radio transmitters with
power supplies too heavy to lift; but we don't see any interactions such
as UPS dropouts, or noticeable loss of performance in the machine tools.

I should add that the internal house wiring is completely up to date,
and the feeders to the workshop and cooker are oversized so that
additional voltage drops are insignificant. Overall, it's just "how
things are", one of the joys of rural living. IMO it still beats the
alternative kind of rural supply, which would be an overhead 11kV supply
coming right up to the property boundary.


Going back to Ben's OP, it may well be that his 1940s house has an
undersized supply cable by modern standards, so it would be worthwhile
to see what the supply company can do. The biggest part of the problem
is getting them to come out at all. If he can persuade them to come out
"because there might be a fault", the blokes on the job might well
decide to uprate the cable anyway.


--
Ian White

The Natural Philosopher

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Jun 5, 2007, 4:43:12 AM6/5/07
to
John Rumm wrote:
> Peter Lynch wrote:
>
>> I wouldn't say it's a problem, necessarily, just that the cable to his
>> house is a particularly long run. At a friends place (way out in the
>> boonies) I've measured a 12V drop when her 2kW kettle is plugged in.
>> Worse, the UPS starts running when the fridge kicks in.
>> Yes the lights do go dim, mo it's not a problem - just the way of things.
>
> That would suggest a supply impedance of something like 1.5 ohms. Which
> if true, certainly could be a problem for things powered by induction
> motors (like fridges) since it would mean that they are drawing over
> their rated current and dissipating more heat in the motor windings.

That does not compute. If they are rn on a lower voltage they will draw
less current surely?

> There is also the danger that motors can stall under load at startup
> (undervoltage can reduce the already limited starting torque).
>

That is certainly true.

Ben

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Jun 5, 2007, 5:17:59 AM6/5/07
to
The Wanderer wrote:
> Ben, you've had two or three people who either work in or used to work in
> the supply industry tell you to contact your local distribution company,
> because in their opinion it's a problem with the distribution network.

I'm away from home at the moment, but I would be interested to measure
the voltage drop before potentially incurring expense (is there a charge
for the distribution company having a look?). I'm expecting the drop to
be quite significant based on the amount of dimming, but what sort of
figure would be acceptable?

tony sayer

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Jun 5, 2007, 5:33:11 AM6/5/07
to
In article <ccWkWuG0...@ifwtech.co.uk>, Ian White
<I...@ifwtech.co.uk> writes

>John Rumm wrote:
>>Peter Lynch wrote:
>>
>>> I wouldn't say it's a problem, necessarily, just that the cable to his
>>> house is a particularly long run. At a friends place (way out in the
>>> boonies) I've measured a 12V drop when her 2kW kettle is plugged in.
>>> Worse, the UPS starts running when the fridge kicks in.
>>> Yes the lights do go dim, mo it's not a problem - just the way of things.
>>
>>That would suggest a supply impedance of something like 1.5 ohms. Which
>>if true, certainly could be a problem for things powered by induction
>>motors (like fridges) since it would mean that they are drawing over
>>their rated current and dissipating more heat in the motor windings.
>>There is also the danger that motors can stall under load at startup
>>(undervoltage can reduce the already limited starting torque).
>>
>In practice it's nothing like that bad. We live in such a house, a
>former farm cottage with a long underground (private) supply from the
>farm. The farm buildings have a direct drop from 11kV,

Just out of curiosity how much of a load can the usual 11KV three phase
line support?. I've noticed over the years that most villages just have
the one line feeding them!.

>Going back to Ben's OP, it may well be that his 1940s house has an
>undersized supply cable by modern standards, so it would be worthwhile
>to see what the supply company can do. The biggest part of the problem
>is getting them to come out at all. If he can persuade them to come out
>"because there might be a fault", the blokes on the job might well
>decide to uprate the cable anyway.
>
>

We had this problem at a local communications site many years ago. The
volts would drop sometimes to around 185! and it was only when the
mobile phone companies moved there that it was upgraded.

Presumably these could stand the expense and paid for it to be done!.
The 240 volt line in looked as if it was made of bell wire and came
several hundred yards over poles from a tiny tranny!....
--
Tony Sayer

Message has been deleted

The Natural Philosopher

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Jun 5, 2007, 6:39:59 AM6/5/07
to
tony sayer wrote:
> In article <ccWkWuG0...@ifwtech.co.uk>, Ian White
> <I...@ifwtech.co.uk> writes
>> John Rumm wrote:
>>> Peter Lynch wrote:
>>>
>>>> I wouldn't say it's a problem, necessarily, just that the cable to his
>>>> house is a particularly long run. At a friends place (way out in the
>>>> boonies) I've measured a 12V drop when her 2kW kettle is plugged in.
>>>> Worse, the UPS starts running when the fridge kicks in.
>>>> Yes the lights do go dim, mo it's not a problem - just the way of things.
>>> That would suggest a supply impedance of something like 1.5 ohms. Which
>>> if true, certainly could be a problem for things powered by induction
>>> motors (like fridges) since it would mean that they are drawing over
>>> their rated current and dissipating more heat in the motor windings.
>>> There is also the danger that motors can stall under load at startup
>>> (undervoltage can reduce the already limited starting torque).
>>>
>> In practice it's nothing like that bad. We live in such a house, a
>> former farm cottage with a long underground (private) supply from the
>> farm. The farm buildings have a direct drop from 11kV,
>
>
>
> Just out of curiosity how much of a load can the usual 11KV three phase
> line support?. I've noticed over the years that most villages just have
> the one line feeding them!.

Quite a lot.
Certainly enough for a few thousand homes.

>
>> Going back to Ben's OP, it may well be that his 1940s house has an
>> undersized supply cable by modern standards, so it would be worthwhile
>> to see what the supply company can do. The biggest part of the problem
>> is getting them to come out at all. If he can persuade them to come out
>> "because there might be a fault", the blokes on the job might well
>> decide to uprate the cable anyway.
>>
>>
> We had this problem at a local communications site many years ago. The
> volts would drop sometimes to around 185! and it was only when the
> mobile phone companies moved there that it was upgraded.
>
> Presumably these could stand the expense and paid for it to be done!.
> The 240 volt line in looked as if it was made of bell wire and came
> several hundred yards over poles from a tiny tranny!....

Thats what was general when this type of stuff was installed - you might
excpect lights, and the odd heater or two in any given dwelling.

Dave Fawthrop

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Jun 5, 2007, 6:59:57 AM6/5/07
to
On Tue, 05 Jun 2007 10:17:59 +0100, Ben <nos...@nospam.com> wrote:

|!The Wanderer wrote:
|!> Ben, you've had two or three people who either work in or used to work in
|!> the supply industry tell you to contact your local distribution company,
|!> because in their opinion it's a problem with the distribution network.
|!
|!I'm away from home at the moment, but I would be interested to measure
|!the voltage drop before potentially incurring expense (is there a charge
|!for the distribution company having a look?). I'm expecting the drop to
|!be quite significant based on the amount of dimming, but what sort of
|!figure would be acceptable?

IIRC the limits are 220 V + 10% - 6%.
No idea what the voltage *drop* on load should be. but measure it anyway so
that you know what you are talking about.

Beware the accuracy of your meter. Allow for that in measurements.

Stephen Dawson

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Jun 5, 2007, 7:13:11 AM6/5/07
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<meow...@care2.com> wrote in message
news:1181029910....@p77g2000hsh.googlegroups.com...

With the greatest of respect, if you feel you are too tired to give advice,
then refrain, becuase you may give the wrong advice.

Message has been deleted
Message has been deleted

John Rumm

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Jun 5, 2007, 9:25:14 AM6/5/07
to
Huge wrote:

> With the greatest of respect, I fear you are confusing Usenet with Real
> Life.

Some of us do try to give the right advice, even when on usenet!

John Rumm

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Jun 5, 2007, 9:53:15 AM6/5/07
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The Natural Philosopher wrote:

>> Which if true, certainly could be a problem for things powered by
>> induction motors (like fridges) since it would mean that they are
>> drawing over their rated current and dissipating more heat in the
>> motor windings.
>
> That does not compute. If they are rn on a lower voltage they will draw
> less current surely?

Depends on the motor type... for a universal motor this is certainly
true. For an induction motor the speed is fixed (by mains frequency and
and a certain percentage of slip). So if you place it under full load at
reduced voltage it will attempt to maintain the same mechanical output,
so it will have to draw more current to compensate.

How much of a problem this is will depend on the magnitude of the drop.
A supply of 210V is unlikely to cause a problem, but falling to 170V say
might.

(I have a friend who managed to get payment for a new freezer out of his
electricity supplier, after it got very upset with the 110V or so the
supplied his property with for a couple of hours)

The Wanderer

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Jun 5, 2007, 10:58:44 AM6/5/07
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On Tue, 05 Jun 2007 10:17:59 +0100, Ben wrote:

> The Wanderer wrote:
>> Ben, you've had two or three people who either work in or used to work in
>> the supply industry tell you to contact your local distribution company,
>> because in their opinion it's a problem with the distribution network.
>
> I'm away from home at the moment, but I would be interested to measure
> the voltage drop before potentially incurring expense (is there a charge
> for the distribution company having a look?).

No, and don't let them try to tell you otherwise. You tell them you are
experiencing flickering lights, which get worse when you switch on any
significant load. You also tell them that the whole installation is
affected, given that you have the annexe on a separate CU.

> I'm expecting the drop to
> be quite significant based on the amount of dimming, but what sort of
> figure would be acceptable?

The statutory voltage must be within the limits 230v +10% -6%. I'll let you
do the maths!

There are also design criteria which I'm afraid I just can't remember for
the reasonable amount of flicker or dimming that can be seen on the lights
because of loads coming on. Steve Dawson or Colin Wilson may be able to
come up with the actual figure.

Note that this dimming or flicker may not necessarily have to take the
supply voltage outside the statutory limits; it is (or was[1]) the step
change in supply voltage perceptible as dimming or flickering on the
lights. F'rinstance, you might have an incoming no-load supply of 250v, but
this could drop to 220v with load, which results in a step change of 30v,
IYSWIM. Like I said, I just can't remember the percentage figures, so treat
my example as just that, an example.

[1] I say 'was' because in this post privatisation era, the standards don't
seem to be enforced as rigorously as they were pre privatisation.....

The Wanderer

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Jun 5, 2007, 11:08:20 AM6/5/07
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On Tue, 5 Jun 2007 10:33:11 +0100, tony sayer wrote:

<snip>

> Just out of curiosity how much of a load can the usual 11KV three phase
> line support?.

Depends on the conductor size. It could quite easily be two or three
megawatts.

> I've noticed over the years that most villages just have
> the one line feeding them!.

Diversity is a wonderful thing! Helps the companies minimise their costs.
Design criteria can range from 1kva upto 5 or 6kva per dwelling, and
transformers can easily withstand shortish periods of overload. Certainly
not unusual for a 100kva transformer to feed 50 to 60 houses, particularly
if they're in a rural location and not too many gin palaces scattered
around.

The Natural Philosopher

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Jun 5, 2007, 11:15:34 AM6/5/07
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Its the tractor welders and cow milking machinery that gets you in that
case.

My house is FUSED for 25KVA...and I am the only one on the transformer..

Stephen Dawson

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Jun 5, 2007, 6:19:59 PM6/5/07
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"The Wanderer" <m...@privacy.net> wrote in message
news:1n8nmnpk2x4ie$.h62bdrtnxbl6.dlg@40tude.net...


> On Mon, 04 Jun 2007 17:02:22 +0100, Ben wrote:
>
>> The Wanderer wrote:

>>> Are you in a rural or urban location? Sounds very much like a problem
>>> with
>>> the distribution network that supplies your property. This can quite
>>> often
>>> be a real problem in rural areas, where distribution networks can be
>>> like
>>> wet string, particularly where there hasn't been much development for a
>>> few
>>> years.
>>
>> Its very much a rural area, and to answer a question from another post
>> the dimming is continuous until the heavy load is switched off. I'll
>> measure the voltage drop and if its excessive report it to the
>> distribution company (and report back here of course).
>
> Just remember that cheap MMs are really only an indication at best. Back
> in
> the days when I used to have to check voltages I carried a (very
> expensive)
> laboratory substandard that was checked annually against a national
> standard. Not unknown for DMMs or cheap analogue MMs to read as much as
> 10-15volts different to the SS! Indeed, I also had (and still have,
> somewhere) an Avo8 that read different to the SS. And it had been for
> recalibration five or six times over the years. :-(


>
> --
> the dot wanderer at tesco dot net

It used to make me chuckle the SS stood for sub-standard, and these were the
most accurate analogue meters availible. I used to use japanese make,
yokogawa for spot tesing, these cost about £800 each.. We then changed from
paper chart recoring meters, to a unit called a Telog Linecorder, which was
a pc based system and the cost went to about £3500, per unit including all
the leads.

We used to be able to tell from the results which side of the connection the
fault was.

meow...@care2.com

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Jun 5, 2007, 7:11:23 PM6/5/07
to
On 5 Jun, 12:13, "Stephen Dawson" <steve.daw...@btconnect.com> wrote:
> <meow2...@care2.com> wrote in message
news:1181029910....@p77g2000hsh.googlegroups.com...
> > On 4 Jun, 19:58, "Stephen Dawson" <stephendaw...@ntlworld.com> wrote:
> >> <meow2...@care2.com> wrote in message
>news:1180903735.4...@k79g2000hse.googlegroups.com...

> >> NT,
>
> >> Stand back from this and leave it to those that have the experience in
> >> this
> >> field, i.e. me. (10 years investigating voltage compliants for an REC,
> >> then
> >> 10 years running my own electrical firm.)

> > I can understand pointing out that I was half asleep at the time, but
> > these kind of comments seem a little off beam.

> With the greatest of respect, if you feel you are too tired to give advice,


> then refrain, becuase you may give the wrong advice.

I think someone needs to get real. All of us overlook something at
times, respond when tired, miss something etc. I've done it a few
times the last few days. To expect perfection from others is not
realistic, to believe in one's own perfection is equally unrealistic,
and to draw the unwarranted conclusions you did above from a simple
mistake does seem rash.

If I'm wrong about that, then let me know when your record is found to
be free of any error or omission.

What is it about human beings that they always want to degenerate into
ego nonsense instead of addressing the question.


NT

Frank Erskine

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Jun 5, 2007, 7:34:57 PM6/5/07
to
On Mon, 04 Jun 2007 18:58:04 GMT, "Stephen Dawson"
<stephe...@ntlworld.com> wrote:


>Stand back from this and leave it to those that have the experience in this
>field, i.e. me.

How can "those" be "me"?

"i.e." means "that is" - perhaps you mean "e.g." meaning "for
example"...

Anyway, why "Stand back from this"? Did you gain your experience by
standing back?

;-)
--
Frank Erskine

The Wanderer

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Jun 6, 2007, 3:26:09 AM6/6/07
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On Tue, 05 Jun 2007 16:11:23 -0700, meow...@care2.com wrote:

> On 5 Jun, 12:13, "Stephen Dawson" <steve.daw...@btconnect.com> wrote:
>> <meow2...@care2.com> wrote in message
> news:1181029910....@p77g2000hsh.googlegroups.com...
>>> On 4 Jun, 19:58, "Stephen Dawson" <stephendaw...@ntlworld.com> wrote:
>>>> <meow2...@care2.com> wrote in message
>>news:1180903735.4...@k79g2000hse.googlegroups.com...
>
>>>> NT,
>>
>>>> Stand back from this and leave it to those that have the experience in
>>>> this
>>>> field, i.e. me. (10 years investigating voltage compliants for an REC,
>>>> then
>>>> 10 years running my own electrical firm.)
>
>>> I can understand pointing out that I was half asleep at the time, but
>>> these kind of comments seem a little off beam.
>
>> With the greatest of respect, if you feel you are too tired to give advice,
>> then refrain, becuase you may give the wrong advice.
>
> I think someone needs to get real. All of us overlook something at
> times, respond when tired, miss something etc. I've done it a few
> times the last few days.

Perhaps you should first ask yourself 'Have I understood what the other guy
was saying? Have I said what I mean? Have I meant what I said?' before
hitting the send button.

> To expect perfection from others is not
> realistic, to believe in one's own perfection is equally unrealistic,
> and to draw the unwarranted conclusions you did above from a simple
> mistake does seem rash.

So are you saying that incorrect or misleading advice shouldn't be
challenged? Especially by posters who have worked in and have considerable
experience in the particular field under discussion.

> If I'm wrong about that, then let me know when your record is found to
> be free of any error or omission.

Of course, the other way of looking at this is there are times when it is
better to say nothing, when one risks contributing nothing of substance to
the thread.

> What is it about human beings that they always want to degenerate into
> ego nonsense instead of addressing the question.

Or could it be that some posters' egos require that they just have to throw
in their two pennyworth.

Or they feel the need to defend themselves because their comments aren't
really germane to the discussion, they've been more than adequately covered
by other posters' comments earlier in the thread, or they're challenged on
the accuracy or relevance of what they've said.

The Wanderer

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Jun 6, 2007, 4:02:39 AM6/6/07
to

> yokogawa for spot tesing, these cost about Ł800 each.

Ah, Yokogawa. I just *couldn't* remember the make, only that it was
Japanese, and with a heavily damped movement that used to swing somewhat
lazily to its reading.

> We then changed from
> paper chart recoring meters, to a unit called a Telog Linecorder, which was

> a pc based system and the cost went to about Ł3500, per unit including all
> the leads.

Dataloggers were only just becoming widespread when I left the industry in
1993, and I'd been away from matters operational anyway for a couple of
years prior to that - preparation and subsequent auditting of company
capital budgets! Mind you, it was nice for a couple of years after I left
to be able to say I'd prepared a company budget of about Ł130m.

meow...@care2.com

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Jun 6, 2007, 4:36:34 AM6/6/07
to
On 6 Jun, 08:26, The Wanderer <m...@privacy.net> wrote:


lifes too short. This is the kind of stuff I was talking about.


NT

Stephen Dawson

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Jun 9, 2007, 10:25:13 AM6/9/07
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"Ben" <nos...@nospam.com> wrote in message
news:46630a02$0$8741$ed26...@ptn-nntp-reader02.plus.net...
> We recently moved to a new house (built in the 40's with an annexe added
> in the 80s). The lights go dim when anything with high current drain like
> a kettle or electric shower is turned on. This works for all different
> combinations of ceiling lights and lights plugged into sockets in the
> house and the annexe, and happens when any high-current appliance is
> switched on in the house or the annexe (which are on different fuseboxes).
> This would suggest to me that the voltage is dropping at the point where
> the mains enters the house, and therefore that the cable coming up from
> the road is under rated. Does this sound like a reasonable conclusion, and
> is it something we should worry about?

Hi Ben, i am interested to know what the problem was.

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