Have looked in the FAQ but no answer to this there...

My electrical consumer unit has MCBs. In the house, each light switch
controls just one light EXCEPT in the lounge where the light switch
controls 10 lights all at once (two pendants each containing 5 bulbs).
Whenever one of the lounge lights blows, the MCB trips, but this never
happens when any of the other lights blow.

Unfortunately the consumer unit is in the garage, only accessible from
outdoors, so when this happens in the middle of the night it's
inconvenient to say the least. Is there any particular reason why the
lights in the pendants cause the MCB to trip when other lights don't? Is
there anything I can do about it?

(The lounge light switch is a dimmer, with press-on-off action.)

Robert

In article ,
Robert Hunt writes:
Have looked in the FAQ but no answer to this there...

My electrical consumer unit has MCBs. In the house, each light switch
controls just one light EXCEPT in the lounge where the light switch
controls 10 lights all at once (two pendants each containing 5 bulbs).
Whenever one of the lounge lights blows, the MCB trips, but this never
happens when any of the other lights blow.

Unfortunately the consumer unit is in the garage, only accessible from
outdoors, so when this happens in the middle of the night it's
inconvenient to say the least. Is there any particular reason why the
lights in the pendants cause the MCB to trip when other lights don't?

They might be nearest the CU, and so have the highest fault current.

Your living room lights will blow 10 times more often than the
filament lamps in any of your other rooms, simply because you have
10 times more of them. Therefore, whatever the chance of the trip
going when a light blows, it's going to happen 10 times more often
for a living room light than for any other light.

Is there anything I can do about it?

What is the rating of the MCB (not just the current rating, but the
associated type (B, C, or D, or 1, 2, 3, 4 if old)?
If it's a type B, 1, or 2, you could probably change it to a type
C which might help a bit (but certainly isn't a cure-all).
You could change it to a 5A BS1361 cartridge fuse carrier, which will
fix the problem. However, a lamp blowing might then kill the dimmer
instead -- the MCB tripping may be saving the dimmer from being fried
instead.

(The lounge light switch is a dimmer, with press-on-off action.)

Use a dimmer which can only be switched on by dimming up from
nothing. IME, lights which blow whilst on seem much less likely
to arc over than those which do so at switchon, although this
is conjecture not backed up by any measurable facts ...

--
Andrew Gabriel

In message ,
(Andrew Gabriel) wrote:


Use a dimmer which can only be switched on by dimming up from
nothing. IME, lights which blow whilst on seem much less likely
to arc over than those which do so at switchon, although this
is conjecture not backed up by any measurable facts ...


Or (slightly more expensive) one of those push-on-off dimmers which
ramps up over a second or so. Again, no facts but I suspect that these
increase the life of filament bulbs.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Don't fight technology, live with it: http://www.livtech.co.uk/
.... If Jack helped you off of a horse, would you help Jack off a horse?

Again, no facts but I suspect that these increase the life of
filament bulbs.

These will have no effect on the life of the bulbs, except maybe because
they never reach full brightness, so run cooler.

The life of a bulb is actually remarkably stable and related to the
evaporation of the filament. Eventually the filament wears down to a point
where it breaks. When you turn a light on, it shocks the filament and is
more likely to break at this point. However, by the time it gets to this
point, it would have broken anyway within about 10 hours if you left it on.
We just normally turn the lights on and off enough that it fails during the
shock stage.

A big study was done on traffic light bulbs that proved that the flashing
amber lights blow after the same period of on time as the red and the green
lights. The flashing had no effect on bulb life at all.

Christian.

My electrical consumer unit has MCBs. In the house, each light switch
controls just one light EXCEPT in the lounge where the light switch
controls 10 lights all at once (two pendants each containing 5 bulbs).

That is a fact of life with MCBs and filament light bulbs. I'm surprised
that other rooms don't trip the MCB, though. When a filament bulb goes, it
draws thousands of amps because the shock of the filament blowing ionises
the gases into a dead short. Fuses are too cr*p to notice, whilst MCBs
actually work, so cut the power.

The solution that works for me is to only use energy saving bulbs. These do
not have this problem. Having ten filament bulbs in one room is excessive
anyway. Have you heard of global warming?

Christian.

The Natural Philosopher wrote in message ...
Robert Hunt wrote:

Have looked in the FAQ but no answer to this there...

My electrical consumer unit has MCBs. In the house, each light switch
controls just one light EXCEPT in the lounge where the light switch
controls 10 lights all at once (two pendants each containing 5 bulbs).
Whenever one of the lounge lights blows, the MCB trips, but this never
happens when any of the other lights blow.


Lucky you. My MCB trips obn just about ANY bub that blows.

Candle bulbs are worst. They take out the dimmers as well.



Unfortunately the consumer unit is in the garage, only accessible from
outdoors, so when this happens in the middle of the night it's
inconvenient to say the least. Is there any particular reason why the
lights in the pendants cause the MCB to trip when other lights don't? Is
there anything I can do about it?

(The lounge light switch is a dimmer, with press-on-off action.)

Robert

robert i have fathomed this out very quickly, as your other lights in
the house are on a loop in loop out system if one light filament goes
then the current (electric) just misses this pendant out and continues
to the next tripping the Circuit breaker.With yours no doubt there is
a juction box in the ceiling taken from loop in loop out, and it is
feeding all the lights in series (ie one to the next and so on in a
line). If this is the case then one gone wrong and it all goes. pop
into your local b&q warehouse and speak to one of the electricians for
some free advice.

robert i have fathomed this out very quickly, as your other lights in
the house are on a loop in loop out system if one light filament goes
then the current (electric) just misses this pendant out and continues
to the next tripping the Circuit breaker.With yours no doubt there is
a juction box in the ceiling taken from loop in loop out, and it is
feeding all the lights in series (ie one to the next and so on in a
line). If this is the case then one gone wrong and it all goes. pop
into your local b&q warehouse and speak to one of the electricians for
some free advice.

I'm afraid none of this makes sense.

Christian.

"alan" wrote
| robert i have fathomed this out very quickly, as your other
| lights in the house are on a loop in loop out system if one
| light filament goes then the current (electric) just misses
| this pendant out and continues to the next tripping the
| Circuit breaker.

Nonsense.

| With yours no doubt there is a juction box in the ceiling taken
| from loop in loop out, and it is feeding all the lights in series
| (ie one to the next and so on in a line).

Nonsense.

| If this is the case then one gone wrong and it all goes. pop
| into your local b&q warehouse and speak to one of the
| electricians for some free advice.

Electricians are not known to frequent B&Q worehouses.

Owain

what is the wattage of each single filament bulb in the pendant ?

Christian McArdle wrote:


A big study was done on traffic light bulbs that proved that the flashing
amber lights blow after the same period of on time as the red and the green
lights. The flashing had no effect on bulb life at all.



That why we all use traffic light bulbs in our houses right?


Christian.

Christian McArdle wrote:

robert i have fathomed this out very quickly, as your other lights in
the house are on a loop in loop out system if one light filament goes
then the current (electric) just misses this pendant out and continues
to the next tripping the Circuit breaker.With yours no doubt there is
a juction box in the ceiling taken from loop in loop out, and it is
feeding all the lights in series (ie one to the next and so on in a
line). If this is the case then one gone wrong and it all goes. pop
into your local b&q warehouse and speak to one of the electricians for
some free advice.


I'm afraid none of this makes sense.



He is thinking of fairy lights on a Christmas tree I think.

Has IMM stated doing elecrical theory from the Bumper Book of How Things
Work and changed his alias?


Christian.

A big study was done on traffic light bulbs that proved that the flashing
amber lights blow after the same period of on time as the red and the
green
lights. The flashing had no effect on bulb life at all.

That why we all use traffic light bulbs in our houses right?

The failure modes are similar. In other countries, they use long life GLS
bulbs anyway.

Christian.

what is the wattage of each single filament bulb in the pendant ?

My guess was 10x40W = 400W total. This would go a substantial way to
actually heating the room if the insulation is up to scratch. 5W candle
bulbs are available on screwfix for £28 for 10, whilst 7W candle bulbs are
£43.60 for 10.

Over the lifetime of the 10 bulbs, which is 5000 hours, you will have paid
for 350kWh of electricity. The standard candle bulbs will have burned
2000kWh. As they last only 1000 hours, you would need 50 of them, costing
£13.77 from the same supplier.

Assuming 6p/kWh.

So we have:

(CFL candle) 43.60 + 21.00 = 64.60
(filament candle) 13.77 + 120.00 = 133.77

The filament candles will have a total cost of ownership more than double
the energy saving type. It will also cause almost 6 times as much global
warming (except where you use electric heating, where it will be reduced
slightly in winter as the heaters won't need to work so hard).

And, don't forget, when they do blow (not so irritatingly frequently) they
won't take out your lighting circuit.

Christian.

In article ,
"Christian McArdle" writes:
A big study was done on traffic light bulbs that proved that the flashing
amber lights blow after the same period of on time as the red and the
green
lights. The flashing had no effect on bulb life at all.

That why we all use traffic light bulbs in our houses right?

The failure modes are similar. In other countries, they use long life GLS
bulbs anyway.

The research was done in the US, where standard mains lamps have
been used in traffic signals, and where long term flashing red and
amber signals are used much more than they are here. Lamp life
turns out to depend only on the total 'on' time, and not the
frequency of switching. This is counter-intuitive because lamps
often blow at switchon, but the last switchon only hastened its
death by an hour or so which is completely insignificant, and the
switchons prior to that had no effect at all on lamp life.

In the UK, we have never used standard mains lamps in traffic
signals. Even when they were mains voltage (which they haven't
been for years), the lamps were special.

--
Andrew Gabriel

what is the wattage of each single filament bulb in the pendant ?

My guess was 10x40W = 400W total.

That's right.

Have you heard of global warming?

The pendants came with the house, so I didn't have much choice about the
10 separate bulbs. I'd have preferred fewer bulbs with higher individual
wattages. The problem with energy-saving bulbs is that they won't fit
neatly into the (decorative) housings... and also that I have a dimmer
switch. But the dimmer switch is probably expendable, and the lack of
neatness might not be too much of a disaster.

The problem with energy-saving bulbs is that they won't fit
neatly into the (decorative) housings...

Not even something like:

http://www.screwfix.com/app/sfd/cat/...70078&id=18951

Christian.

Tripe Master wrote:

On Fri, 29 Aug 2003 15:51:07 +0100, Robert Hunt
wrote:


My guess was 10x40W = 400W total.

That's right.

and also that I have a dimmer switch.


Be aware that dimmer switches may be limited to 100w or 250w. If you
are running 400w off the dimmer switch that may be a cause for
concern.


All MY dimmers are 400W versions.



PoP

On Fri, 29 Aug 2003 19:19:18 +0100, The Natural Philosopher
wrote:

All MY dimmers are 400W versions.

There are larger ones of course

I dealt with a light cluster recently which was on a dimmer switch,
and remember the load was about 400w, with the dimmer switch rated
somewhat below that, hence why I mentioned it.

PoP

Just solving the problem would be the easiest, by replacing the ill
designed MCB with something with more appropriate characteristics,
like a wire fuse.

and then sit back and watch the fireworks

All MY dimmers are 400W versions.

There are larger ones of course

I dealt with a light cluster recently which was on a dimmer switch,
and remember the load was about 400w, with the dimmer switch rated
somewhat below that, hence why I mentioned it.

Outcomes of my investigations:

The dimmer switch was rated for 250W, so it was indeed dangerous. The
previous owners were into slight-dodgy DIY so this isn't surprising.
Anyway, the dimmer switch has now been replaced with a standard switch
(I might consider changing it for a 450W dimmer at a later stage). So
many thanks to Tripe Master for pointing this out.

Energy-saving bulbs don't seem to be a possibility: the height available
(from the base of the bulb to the top of the acid-glass shade on each
housing) is 89mm, and 40W-equivalent energy-saving bulbs are much taller
than that. (The housings are designed for 40W golf bulbs.)

My next move is to try a type C MCB instead of a type B.

Thanks to all who replied!

On Thu, 28 Aug 2003 12:35:29 UTC, "Christian McArdle"
wrote:

robert i have fathomed this out very quickly, as your other lights in
the house are on a loop in loop out system if one light filament goes
then the current (electric) just misses this pendant out and continues
to the next tripping the Circuit breaker.With yours no doubt there is
a juction box in the ceiling taken from loop in loop out, and it is
feeding all the lights in series (ie one to the next and so on in a
line). If this is the case then one gone wrong and it all goes. pop
into your local b&q warehouse and speak to one of the electricians for
some free advice.

I'm afraid none of this makes sense.

Unless the house is wired with Christmas tree lights!


--
Bob Eager
rde at tavi.co.uk
PC Server 325*4; PS/2s 9585, 8595, 9595*2, 8580*3,
P70...

(Wheelbarrowbob) wrote in message ...
Just solving the problem would be the easiest, by replacing the ill
designed MCB with something with more appropriate characteristics,
like a wire fuse.

and then sit back and watch the fireworks

You're trolling.

Regards, NT

(Wheelbarrowbob) wrote in message ...
Just solving the problem would be the easiest, by replacing the ill
designed MCB with something with more appropriate characteristics,
like a wire fuse.

and then sit back and watch the fireworks

You're trolling.

Regards, NT

True, but I think it would be a backward step, as his overcurrent protective
deice is doing what it is designed to do. I think the OP was more concerned
with the frequency of the bulbs blowing and his under rated dimmer switch.

Away from the group could you shed any light on a questionn on my 2361 course,
reference insulation testing on a circuts this is the questiun as laid out on
the test paper. " iii Explain that the requierments of the IEE Regulations for
this test when carried out on the cooker when disconnected."
I know the test procedure for lighrting and power circuits and I would have
assumed a cooker cicuit would have been the same. Any help appreciated

In article ,
(Wheelbarrowbob) writes:
Away from the group could you shed any light on a questionn on my 2361 course,
reference insulation testing on a circuts this is the questiun as laid out on
the test paper. " iii Explain that the requierments of the IEE Regulations for
this test when carried out on the cooker when disconnected."
I know the test procedure for lighrting and power circuits and I would have
assumed a cooker cicuit would have been the same. Any help appreciated

Does this mean testing the cooker circuit with the cooker
disconnected, or testing the cooker when disconnected?
It sounds like the latter, but that's part of PAT testing
and not installation testing.

For PAT testing, a cooker (with electric heating elements)
is allowed to fail an insulation test when cold, but must
not when it has warmed up and and had time to drive off
any moisture.

--
Andrew Gabriel