spotlight keep tripping switch Ask questions and find answers to many subjects relating to electrics and electrical work

[vikz]

hi Got a really annoying problem with 2 light fittings in my kitchen, each one has 4 halogen GU10 bulbs but they keep on fusing and tripping my fuse. What could be causing this? When we had our eletric shower fitted years ago the electrican put all our lights on to 1 fuse in order to fit in fuse for shower, could this be causing the problem? Think its 5amp fuse for lighting.

[ericmark]

4 x 50watt x 2 = 400watts = 1.7amp plus tungsten lamps use more current on switch on. So yes too much load on the circuit. There are a number of ways to cure this. But much is dependent on room, types of lamps used etc. It may be as simple as bigger fuse but you need someone on site to check best way forward. I would contact the electrician who fitted your spot lights. I have tried to look up fuse ratting required for GU10 lamps they are not listed in my version of BS 7671 but they may be limited to 6 amp like the other small lamp fitting. If you wait I am sure some one will clarify as to max amps allowed on fuse.

[sparx]

Hi, you don't say the wattage of the lamps but worst case 8X50W = 400w running load when on & hot but at switch on of GU10 types can take 2,or 3 times that for short time due to cold filements low resistance ie approx 800-1000w surge. maths says 230V X 5A = 1150W available on lighting circuits so if several other lights on when kitchen lights turned on could cause the prob.
If these are mains voltage lamps not 12v via transformer try some lower wattage lamps for a while, say 35W each & see if prob. goes away,
regards SPARX

[vikz]

[vikz]

hi thanks for your advice. My GU10 lights are 50watt and they can pop even when only one other light in the house is on. They are really annoying me as fuse box is behind my tv so always having to move it to put fuse back on.

[ericmark]

Fuses are relatively slow to blow on overload but fast on short circuit and as Sparx says your not really over the top. But miniature circuit breakers are fast on overload but slower on short circuit and a 150 watt bulb takes 10 amp for a few micro seconds on first switch on. "Osram web site" and you say "put fuse back on" which makes me think you have a trip not fuse. I would say the trip is likely to be faulty, to trip so easy but so many lights (300 watt) switching on together is not helping. Two ideas, one change the trip and depending on the test results maybe lift one one type number to for example D but it would need checking first. Or change light switch for dimmer switch where it is gradually turned on. i.e. Turn to switch on, not type where one pulls to switch on at per-set output. But since it will need some measuring and calculation to select best way forward it may be better to call in an electrician who can recommend the best option after a site visit.

[vikz]

Hi thanks for your help but I am a woman who is getting a bit out of my depth in understanding all technical stuff im affraid. I managed to get electrician to have quick check of my fitting and he said it was reading a resistance (what ever that means)when it should not. Could this be causing problem? also agreed that could be nearing limit for breaker but try as you said lower wattage bulbs first. If all else fails could I change 5A fuse breaker to 10 or would this not help? Sorry for being a pest but I'd rather get your advise first as being a female I often feel that some of these tradesmen could tell me anything to make some cash by making the job alot bigger than it needs to be.

[ericmark]

I am sure smaller bulbs will help. Most good electrical wholesale places have cold cathode bulbs on display. If they will fit these give reasonable light without heat and are only 11 watts each. But being a little longer stick out of some fittings in unacceptable way. But worth looking at.

[ericmark]

I am sure smaller bulbs will help. Most good electrical wholesale places have cold cathode bulbs on display. If they will fit these give reasonable light without heat and are only 11 watts each. But being a little longer stick out of some fittings in unacceptable way. But worth looking at.

[chris_on_tour2002]

changing the 5 amp fuse would be illegal and dangerous. its there to protect you and if the lights are running from your lighting circuit (I assume they are) then you must keep it on a 5 amp fuse and find another way to resolve the problem.

[333rocky333]

You say you move the telly to PUT it on ,

So it is an mcb if you just reset it
If it was a fuse you would be changing fusewire each time.

So is it a FUSE or a MCB

The MCB or FUSE is to protect the wire if you put a 10 in it may be too big for the wire

If there is a problem the thing will not go off so fast BUT will overheat the wire and possibly cause a DANGEROUS situation, it may be possible,but I would not advise you personally to do that YOURSELF unless your electrically competent.

[vikz]

Hi sorry im confusing you I did say I know nothing on eletrics. Take it it is a MCB it is tripping breaker for my lights which is 5A. As I said used to have 2 5A one for upstair lighting and one for downstair lights but had them put on to one as needed space to fit eletric shower Since it is illegal n dangerous I wont be changing to one 10A as I thought I might be able to do.

[333rocky333]

It is important as a 5a mcb will trip with a lower amps than a 5a fuse would.

Stick with it your doing ok, just that tripping and fusing in this case makes a difference.

A good elect or someone with a clamp on ammeter can tell you exact amps load with all lights on

Personally I dont think your over 5amps

WHEN you had two 5 amp trips they may only have had about 2 amp on each , now the two are together it could still be only 4amps ,as you obviously know, this would still be within your 5 amp mcb limit

As 5 amps is aprox 1200 watt this is the equivalent of about 18 sixty watt lamps before you overload it.
Your previous upstairs fuse with 4 sixty watt bulbs on would have only used about one amp.

Have you ever had to change the lamps , if so did you notice if the lampholders and any visible parts look burnt or anything.

When you say the bulb goes pop ,please expand

Does all the bulbs work up till the mcb trips and once reset that bulb no longer works.

If so is it the same bulb each time

or

Does the thing trip and on reset all bulbs are still working

Also

Does this occur when turning on that light
Or
How long is the light on before this happens
And how many times has this occured

Apoligies for all the questions but we are trying to advise how you can get this issue resolved
Regards R

[vikz]

Hi After counting I would have been around the 1200watts with around 24 bulbs and yes mcb trips when putting switched on, kitchen lights are on 2 seperate switches and problem happening with both but not always the same bulb that has gone when reset it. Only mean when say pop that heard bulb make a slight popping noise when switched on and tripped the mcb 2 bulbs went once at same time.

[333rocky333]

If then every time it trips, on switch on and the bulb blows
It is less likely to be overload ,

An overloaded circuit usually would trip only, and should not blow gu10 lamps

It sounds like when you switch on the bulb shorts out and trips the circuit

Check they are correct bulbs for the fitings and not cheap ones.

Depending how old the fittings are
It is possible the fitting is damaged usually by heat of lamps
Did the lampholders and wires look burnt

If wires in light are burnt up the insulation resistance between LIVE and NEUTRAL becomes low

This shorts out and trips the mcb when you switch it on

This may be what the previous man said

If you are 100% sure it is only when you switch them lights on
maybe you need to get them lights taken down and tested

Your load is high but do you have all 24 lights on together

Not sure from memory but I think you can allow 66% diversity on domestic lighting circuits