MCB fuse keeps tripping on lighting circuit

[str]

I seem to have a problem with one of the lighting circuits in my office, which was recently refurbished by the landlord.

Within one room there are 2 pendant light fitting, which each have 12 candle bulbs - a bulb will blow on either one fairly regularly, say at least 1 every 2 weeks, whcih then trips the fuse.

Whilst this is not a major issue in that we can just reset the fuse, it makes me think that there may be an issue somewhere - the incorrect rated fuse?

any ideas?

 

[oharaf]

Bulbs blowing are aregular cause of MCB's tripping, candle bulbs are a PITA in my opinion.

The lighting circuit will probably be on 6 amp MCB, check this.

Has the landlord shown you his annual PIR check?

If he has recently changed some fittings he may have made a poor or loose connection.

Get in touch with him and complain!!!

 

[str]

thanks for that.

we have had the landlords electrician back in, who has said that he can't find any fault.

The light fittings are not new but the wiring is - is a 6 amp MCB large enough for 2 fittings of 12 bulbs each?

 

[sm1thson]

Bulbs blowing are aregular cause of MCB's tripping, candle bulbs are a PITA in my opinion.

agreed

The lighting circuit will probably be on 6 amp MCB, check this.

most likely. no problem with that.

Has the landlord shown you his annual PIR check?

there is no obligation for an annual pir check is there?

If he has recently changed some fittings he may have made a poor or loose connection.

true, do any light flicker, otherwise you dont have much to go on there other than a guess

Get in touch with him and complain!!!

about what?

candle bulbs blow more often, having multiple ones naturally further increases the chance of having one of them blow. if you buy cheap ones they blow even more often.

 

[BS3036]

What wattage lamps are you using?

 

[str]

60W

 

[electronicsuk]

60W

With 60w lamps the circuit is just a tad overloaded. Not enough to worry about if the office is the only thing on the circuit, but it makes it all the more likely for nuisance tripping on the MCB, as you don't need a lot to tip it over the edge.

Would suggest you try purchasing some quality lamps of a lower wattage (say, 40w) from a respected manufacturer such as Osram or GE, and see how things go. Other option is to replace all with compact fluorescent 'energy saving' lamps.

 

[JohnD]

I agree, use CFLs. It will cut your electricity bill, reduce maintenance costs in changing them, and put an end to MCB tripping

 

[pbar]

If you have 24 bulbs at 60W -

(24 bulbs x 60 watts) / 230 volts = 6.26 amps

So yes, it's overloaded and low energy bulbs will cure that.

 

[JohnD]

additionally, many filament lamps cause a momentary surge when they burn out, this does not happen with CFLs

If you have a bulb with an average life of 1,000 hours, and you use it 10 hours a day, you can expect it to burn out every 100 working days or so, on average. However, if you have 24 such bulbs, you can expect one of them to burn out every 4 working days or so The cost of a set of CFLs is trivial compared to the inconvenience of changing them, never mind losing power to the circuit if the MCB trips.

If they are in a fancy fitting like a chandelier you can get CFLs in fancy designs. They all last more than 5,000 hours these days, some last 10,000 hours or more