Hi,

I am having a problem with the downstairs lighting circuit which I
hope someone will be able to help me with.

For the past few weeks, the light circuit is blowing ramdomly, but can
be about 10 minutes or so. What is strange, is that this can happen
even with all the lights switched off.

I am finding it hard to understand the cause, as logically, a faulty
wire should exhibit predicatable results. I would appreciate any
advice or tips which i could try in order to reduce the area of
investigations. ONe room has a dimmer switch and the kitchen has a
halagon light, but the problem remains even with all the lights off.

Your help is warmly appreciated.

Regards
Mark

"Mark Smith" wrote in message
m...
Hi,

I am having a problem with the downstairs lighting circuit which I
hope someone will be able to help me with.

For the past few weeks, the light circuit is blowing ramdomly, but can
be about 10 minutes or so. What is strange, is that this can happen
even with all the lights switched off.

I am finding it hard to understand the cause, as logically, a faulty
wire should exhibit predicatable results. I would appreciate any
advice or tips which i could try in order to reduce the area of
investigations. ONe room has a dimmer switch and the kitchen has a
halagon light, but the problem remains even with all the lights off.

Your help is warmly appreciated.

Regards
Mark

Rats or squrills? Use a megger to find the problem.

"Mark Smith" wrote in message
m...
Hi,

I am having a problem with the downstairs lighting circuit which I
hope someone will be able to help me with.

For the past few weeks, the light circuit is blowing ramdomly, but can
be about 10 minutes or so. What is strange, is that this can happen
even with all the lights switched off.

I am finding it hard to understand the cause, as logically, a faulty
wire should exhibit predicatable results. I would appreciate any
advice or tips which i could try in order to reduce the area of
investigations. ONe room has a dimmer switch and the kitchen has a
halagon light, but the problem remains even with all the lights off.

Your help is warmly appreciated.

Regards
Mark

I had a similar problem recently - eventually I found a pinched live wire in
one ceiling fitting - my guess is that it occassionaly shorted to earth when
the fitting was hot. I suggest using a meggar but not everyone has one

In article ,
Peter Andrews wrote:
I had a similar problem recently - eventually I found a pinched live
wire in one ceiling fitting - my guess is that it occassionaly shorted
to earth when the fitting was hot. I suggest using a meggar but not
everyone has one

A normal DVM should help show this sort of fault too.

--
*Age is a very high price to pay for maturity.

Dave Plowman London SW
To e-mail, change noise into sound.

Mark Smith wrote:

I am finding it hard to understand the cause, as logically, a faulty
wire should exhibit predicatable results. I would appreciate any
advice or tips which i could try in order to reduce the area of
investigations. ONe room has a dimmer switch and the kitchen has a
halagon light, but the problem remains even with all the lights off.

As a first stab, you could disconnect the cable at the CU and measure
the resistance between L & N, and L & E using a multimeter. If you get
anything other than open circuit with the lights turned off then you
have found your problem - now it is a case of following it from rose to
rose to work out which cable it is.

If you do get open circuit, then that is where a test with a megger
(i.e. high voltage resistance tester) would help next.


--
Cheers,

John.

/================================================== ===============\
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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"Mark Smith" wrote in message
m...
Hi,

I am having a problem with the downstairs lighting circuit which I
hope someone will be able to help me with.

For the past few weeks, the light circuit is blowing ramdomly, but can
be about 10 minutes or so. What is strange, is that this can happen
even with all the lights switched off.


As nobody has suggested faults between neutral and earth, check this out as
this will trip a RCD if neutral to earth volts is significant, like a few
volts. I think its about 1v-3v here. If the neutral voltage is drifting
about at your location that might explain why it trips at random.

j

John wrote:

As nobody has suggested faults between neutral and earth, check this out as
this will trip a RCD if neutral to earth volts is significant, like a few
volts. I think its about 1v-3v here. If the neutral voltage is drifting
about at your location that might explain why it trips at random.

I thought I would leave that possibility out since it sounded like the
MCB/Fuse for the circuit was opening rather than a RCD (which if present
may not even be protecting the lighting circuit). Perhaps the OP could
give us some more details of his setup?


--
Cheers,

John.

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

Chaps, many many thanks for your expert advice. I havent got a clue
what a megger is :-), but I hope my electician knows...

Hopefully a process of elimination will find the bugger...

Cheers
Mark



John Rumm wrote in message ...
Mark Smith wrote:


If you do get open circuit, then that is where a test with a megger
(i.e. high voltage resistance tester) would help next.


--
Cheers,

John.

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

Mark Smith wrote:

Chaps, many many thanks for your expert advice. I havent got a clue
what a megger is :-), but I hope my electician knows...

Its like an ohm (i.e. resistance) meter, only instead of using test
voltage of a few volts like a multimeter, it uses 500V or more.

The purpose is to find those trickey faults which when measured at DC
low voltage do not show up. However at mains voltage the insulation
starts to break down (electrically) and conduct making the fault appear.
So the megger test does a resistance test at higher than mains voltage
to cause the same breakdown to occur, so which you can then detect and
measure the problem.

Hopefully a process of elimination will find the bugger...

Yup - a binary chop may be the quickest. If you can see a fault with a
multimeter then you can disconnect say half the circuit (at a ceiling
rose). Keep halving the remainder until you isolate the cable run that
has the problem.

(you may find that the cable is fine, but you have a poor connection in
a rose - the taking appart and reassembly procedure will probably fix
that).


--
Cheers,

John.

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