MCB tripping when bulb goes - will type C help

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The MCBs on our lighting circuits nearly always trip when a blub goes. As the fuse box is in the (windowless) garage this can be a bit annoying if it's the downstairs circuit that has gone (esp if kids mave moved the torch, used batteries etc).

Could this be solved by fitting Type C MCBs?

Alternatively I fitted a 150W PIR floodlight to the garage last year (as we were forever leaving the lights on when popping in and out). Wouldn't be too hard to move this to it's own circuit.
 
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mcb is doing its job, if they (your blubs) blow on a regular basis find out why,don`t use cheap cack.
 
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From Wiki
and there is a case to be made for using type C breakers on lighting circuits because they are much less prone to tripping with the brief current surge that occurs when a lamp fails than a type B is

Thanks
 
My kitchen spots (very close to CU) trip the MCB even though it's a C6 :cry: Nothing else does, I've wondered if it might be the length of cables to the other floors that helps.

Most of my other lights have CFLs now, which (apart from lasting years and years and saving energy) don't trip the MCB when they eventually expire. Where they show, I don't like the look of the tubular ones but got a carton of rather nice-looking Globes (Phillips do good ones but these were cheaper - £31.50 for 8 incl VAT and carriage will last me a while)
LALEG24BC.JPG




p.s. I had to calculate the EFLI but was well inside
 
You still need to do a loop impedance test to make sure a type C would disconnect in time.

If you don't do this before changing the mcb, the consequences could be fatal, especially if somebody's been at your edison screw light fittings (if you have any!), and changed the polarity unknowingly.

Best to use good quality lamps , even energy savers can last a long while.

If you are that worried about the lights going out, consider installing a couple of non maintained emergency light fittings on your lighting circuit, then when it happens again , you wont be totally in the dark.
 
From the Wiki -

The wiring regs say that a socket circuit should have a disconnect time of 400ms. Lighting circuits, by contrast, require a 5s disconnect time,and there is a case to be made for using type C breakers on lighting circuits because they are much less prone to tripping with the brief current surge that occurs when a lamp fails than a type B is. At 5 seconds the curves for type B and C breakers have almost met, i.e. there is very little difference in the earth loop resistance limits for a circuit with that disconnection time.

I'd appreciate some clarification on this myself because MCB nuisance trips caused when bulbs fail are a right royal pain.
 
The efli of a circuit when an MCB is used should be such as it disconnects the circuit on its magnetic setting under fault conditions, i.e. 5x for a type B or 10x for a type C.
For a C6 breaker to operate correctly the maximum efli is given by 240v/(10x6) = 4 ohms. As this is a design figure i.e. at the maximum operating temp of a circuit, as a rule of thumb for measurement @ 10-20ºC the efli should not exceed 3/4 (three quarters) of the maximum figure. This would mean a maximum figure of 3 ohms is acceptable.
In contrast, a B6 breaker can have a max measured of 6 ohms.
There are other ways of calculating the max efli, the ones in the OSG are 80% figures.
 

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