Circuit breaker activates when bulb pops.

[fatty]

My parents' house is 25 years old and has never had an electrical problem. Recently a new 'fusebox' (or whatever the pro term is) was fitted, containing trip switches (rather than fuse wire as in the old one). Since the fitting bulbs on the downstairs ring pop more frequently and when a bulb pops the whole lighting circuit is tripped. Surely this can't be normal?

Any thoughts?

Can the trip switch sensitivity be altered?

Is there a fundamental problem in the circuit?

Thanks.

 

[JohnD]

Sadly it is not unusual. When a filament blows it creates a short-lived surge in current drawn, whi often trips MCBs.

Some say that better quality bulbs, such as Osram, are better than cheap bulbs.

I find spotlights are worst for it.

However, CFLs (energy-saving bulbs) do not have this problem. There is a lot to be said for fitting these. They also save money and last longer.

 

[fatty]

Wow! I didn't expect that answer. If it is a common problem, shouldn't MCBs be designed with higher tolerances?

As for spotlights (in their kitchen), they are the worst and since the last time one of those bulbs popped and launched itself across the room, my mother is reluctant to use them.

I'll suggest the energy savers, but isn't there a problem with the amount of light they emit?

Thanks for the lighting quick reply by the way.

 

[JohnD]

MCBs are designed to trip when there is a current which exceeds the design current in order to protect the cable from overload, so they are only doing their job.

Subject to test and calculation of the circuit characteristics and safety, it is possible to fit a slower-acting MCB, but even these can trip from a blowing spot. I had one happen a few days ago.

CFLs are available in a growing range now, including spots and a rather attractive globe that looks good in a lampshade.

http://www.tlc-direct.co.uk/Main_In...Tubes_Index/Lamps_Energy_Reflector/index.html

http://www.tlc-direct.co.uk/Main_In...ps_and_Tubes_Index/Lamps_Energy_1a/index.html

 

[Adam_151]

Many would argue that the circuit isn't properly designed and C curve breakers or BS1361 fuse should have been fitted

Some would however just argue that the lamps you must be using must just be of poor quality


FWIW: MCBS come in with different tripping curves on the magnetic part* (the part that makes it trip in a handful of hundreths of seconds if a short circuit or fault to earth occurs)

B curve are used for general domestic use and must trip instantly if more than 5 times the nominal current flows, but less than three times the nominal current must not trip them on the magnetic part, the exact value therefore will be somewhere between 3 time and 5 times the nominal current

C curve for used for light motors, discharge lighting, etc and sometimes for general purpose for commerial and industrial applications, between 5 and 10 times the nominal current for thse

D curve are for special purposes, heavy welding sets, x-ray machines, etc, between 10 and 20 times the nominal current to get an instant trip on these

*there is also a thermal part thats the same across all of them of the same nominal rating that gradially heats up if the nominal rateing is exceeded and may take upto an hour to trip if the overload is very slight

 

[fatty]

That's a lot of information for my small brain, but thanks. It's very helpful.

 

[Adam_151]

That's a lot of information for my small brain, but thanks. It's very helpful.

Get a sparky in to test the ELFI to see if he can swap the B6 breakers for C6 ones

 

[securespark]

[in football-style chant] Osraaaam, osraaaam, osraaaaaaaaaaaam!

 

[JohnD]

I calculated I can use a C6, but it still trips when a kitchen spotlight blows

I thought I heard someone shouting in the distance!