This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled by
a 4 gang light switch.
This afternoon the lighting mcb has tripped twice for no obvious reason.
Never happened before. Power circuits unaffected.
Only change I have made recently is to change a tube and starter, 2 days
ago.
All lighting cables are 1.5mm surface mounted and 2.5 - 3.00 M above ground.
I have had a bit of a rodent problem recently but suspect that is not
relevant.
I can't track the problem down as I cannot make it happen.
A bit worrying as I'm going away for a few days. The lights will not be left
turned on.

Any thoughts please?
Nick.

I do have an angle grinder and a multimeter.

In message , Nick
writes
This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled by
a 4 gang light switch.
This afternoon the lighting mcb has tripped twice for no obvious reason.
Never happened before. Power circuits unaffected.
Only change I have made recently is to change a tube and starter, 2 days
ago.
All lighting cables are 1.5mm surface mounted and 2.5 - 3.00 M above ground.
I have had a bit of a rodent problem recently but suspect that is not
relevant.
I can't track the problem down as I cannot make it happen.
A bit worrying as I'm going away for a few days. The lights will not be left
turned on.

Any thoughts please?

Trip it yourself before you go?

--
Tim Lamb

On 30/04/2014 19:59, Nick wrote:
This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled by
a 4 gang light switch.

Test it by running with half the lights on for a while:

1111 = trips
1100 = ?A
0110 = ?B

The results of A and B tells you which circuit is defective.

Then run with just that circuit hot and see if it trips.

This afternoon the lighting mcb has tripped twice for no obvious reason.
Never happened before. Power circuits unaffected.
Only change I have made recently is to change a tube and starter, 2 days
ago.

It might be relevant but I don't see how.

All lighting cables are 1.5mm surface mounted and 2.5 - 3.00 M above ground.
I have had a bit of a rodent problem recently but suspect that is not
relevant.

It might be - they enjoy nibbling grey or black PVC for some reason.

I can't track the problem down as I cannot make it happen.
A bit worrying as I'm going away for a few days. The lights will not be left
turned on.

Any thoughts please?
Nick.

I do have an angle grinder and a multimeter.

While you are away isolate the faulty lighting circuit at the fuse box
or breaker just in case there is a charring rodent somewhere slowly
approaching red heat. A live to earth fault will trip the MCB but if the
critter is across live to neutral...

--
Regards,
Martin Brown

"Nick" wrote in message
...
This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled
by a 4 gang light switch.
This afternoon the lighting mcb has tripped twice for no obvious reason.
Never happened before. Power circuits unaffected.
Only change I have made recently is to change a tube and starter, 2 days
ago.
All lighting cables are 1.5mm surface mounted and 2.5 - 3.00 M above
ground.
I have had a bit of a rodent problem recently but suspect that is not
relevant.
I can't track the problem down as I cannot make it happen.



A bit worrying as I'm going away for a few days. The lights will not be
left turned on.

Well I would suspect that there is nothing to worry about if the lights are
turned off. Probably a shagged ballast that will show up sooner or later.

Do the sensible thing and turn the power off to the lights at the CU whilst
you are away.



--
Adam

On 30/04/2014 19:59, Nick wrote:
This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled by
a 4 gang light switch.
This afternoon the lighting mcb has tripped twice for no obvious reason.
Never happened before. Power circuits unaffected.
Only change I have made recently is to change a tube and starter, 2 days
ago.
All lighting cables are 1.5mm surface mounted and 2.5 - 3.00 M above ground.
I have had a bit of a rodent problem recently but suspect that is not
relevant.
I can't track the problem down as I cannot make it happen.
A bit worrying as I'm going away for a few days. The lights will not be left
turned on.

Any thoughts please?
Nick.

I do have an angle grinder and a multimeter.



Change the trip.
They do wear out, and a new one will still protect the circuit.
Its far worse when you have a fault and the trip doesn't work.

On 30/04/14 19:59, Nick wrote:
I have had a bit of a rodent problem recently but suspect that is not
relevant.

IN my case changing a bulb didn't work
Changing the 12v transformer didn't work but did reveal the fat dead
mouse still gripping the mains cable...

--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

In article , Nick
wrote:
This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled
by a 4 gang light switch. This afternoon the lighting mcb has tripped
twice for no obvious reason. Never happened before. Power circuits
unaffected. Only change I have made recently is to change a tube and
starter, 2 days ago. All lighting cables are 1.5mm surface mounted and
2.5 - 3.00 M above ground. I have had a bit of a rodent problem recently
but suspect that is not relevant. I can't track the problem down as I
cannot make it happen. A bit worrying as I'm going away for a few days.
The lights will not be left turned on.

Any thoughts please? Nick.

I do have an angle grinder and a multimeter.

faulty choke. It happens.

--
From KT24

Using a RISC OS computer running v5.18

"Martin Brown" wrote in message
...
On 30/04/2014 19:59, Nick wrote:
This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled
by
a 4 gang light switch.

All lighting cables are 1.5mm surface mounted and 2.5 - 3.00 M above
ground.
I have had a bit of a rodent problem recently but suspect that is not
relevant.

It might be - they enjoy nibbling grey or black PVC for some reason.

When i first had pet rats, i found out they absolutely loved eating the
scart cables linking the sky box to the tv in my bedroom, suddenly one
colour would disappear and the little bugger had got to the juicy copper
cores again,

I asked the vet if there was anything i could put on the cables to deter her
from eating them, he said to try that bitter lemon stuff you use to stop
dogs licking their wounds,

Big mistake, that stuff was like a marinade to the rat, tho it did keep the
cables alive a little longer as she'd lick all the bitter lemon off before
devouring the actual cable,

Someone then suggested washing up liquid, nope, rats like that too it seems,
tho it did turn her turds green, and i am sure she farted bubbles for a
while.

There is just something in the cable make up that is irresistible to rats
and mice, some say it's the electric current in the cable that attracts
them, but mine seem'd to prefer signal cables over mains cables....
Tho i will never forget when Nugget the rat chewed through the phone line to
the adsl box, we heard a squeak and the internet died, i looked behind the
sofa and watched him move a few inches up the cable he had just severed, and
in one snip he severed it again.... with the accompanied squeak as the cable
bit back, he sat and thought for a few moments, then moved double the
distance up the cable and 'snip - squeak' again,

i'm sure if i left him to it, he'd reach the socket, then start burrowing to
follow the cable back to the exchange.

Reminds me of this dilbert strip:
http://dilbert.com/strips/comic/2007-05-30/

On 30/04/2014 21:11, Gazz wrote:

There is just something in the cable make up that is irresistible to
rats and mice, some say it's the electric current in the cable that
attracts them, but mine seem'd to prefer signal cables over mains
cables....
Tho i will never forget when Nugget the rat chewed through the phone
line to the adsl box, we heard a squeak and the internet died, i looked
behind the sofa and watched him move a few inches up the cable he had
just severed, and in one snip he severed it again.... with the
accompanied squeak as the cable bit back, he sat and thought for a few
moments, then moved double the distance up the cable and 'snip - squeak'
again,

Putting the item in a cat's bed/sleeping place does seem to repel the
rat. There's an idea that fear of cats is an inherited/evolutionary
response. May not make for a happy rat though.

Gareth

On 30/04/2014 19:59, Nick wrote:
This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled by
a 4 gang light switch.
This afternoon the lighting mcb has tripped twice for no obvious reason.
Never happened before. Power circuits unaffected.

At switch on, or when running for a time?

Given the age of the installation, a plausible cause would be a ballast
in one of the fittings is suffering insulation failure of some
description...

Only change I have made recently is to change a tube and starter, 2 days
ago.

Might have changed the load on the ballast slightly - could be enough if
its on its last legs. You could see if you get a repeat trip with that
tube removed.

All lighting cables are 1.5mm surface mounted and 2.5 - 3.00 M above ground.
I have had a bit of a rodent problem recently but suspect that is not
relevant.
I can't track the problem down as I cannot make it happen.
A bit worrying as I'm going away for a few days. The lights will not be left
turned on.

Any thoughts please?

Insulation resistance check from L+N to E might be a useful test.



--
Cheers,

John.

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

On 30/04/2014 20:17, Martin Brown wrote:
A live to earth fault will trip the MCB but if the critter is across
live to neutral...

... it'll be getting about 10v, which probably isn't enough to do
anything (except trip the breaker)

Andy

On Wednesday, April 30, 2014 7:59:15 PM UTC+1, Nick wrote:

This is in my workshop which I built, and wired, about 30 years ago.
There are 12 fluorescent light fittings in 4 banks of 3. These controlled by
a 4 gang light switch.
This afternoon the lighting mcb has tripped twice for no obvious reason.
Never happened before. Power circuits unaffected.
Only change I have made recently is to change a tube and starter, 2 days
ago.
All lighting cables are 1.5mm surface mounted and 2.5 - 3.00 M above ground.
I have had a bit of a rodent problem recently but suspect that is not
relevant.
I can't track the problem down as I cannot make it happen.
A bit worrying as I'm going away for a few days. The lights will not be left
turned on.
Any thoughts please?
Nick.
I do have an angle grinder and a multimeter.

You've most likely got an insulation problem from L to N or L to E somewhere. Things that could help narrow it down a
- insulation test L+N to E
- insulation test L to N with all tubes removed
- disconnecting half the fittings (or some) and see if it still trips or not, repeat to narrow it down further each time


NT