Help.. Light Bulbs Blow When Switched On

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i hope someone can help me.. first of all im no electrician. we rent a house and ever since we have lived here he have had this problem.. we are sick of asking the landlord to fix as he only sends round un qualified people which only say oww you need new light fittings and so on. he had new ones fitted and still no fix..

ok so the problem.. when we switch on the light in the kitchen sometimes its ok.. then all a sudden one random day the bulbs blows. sometimes this trips the fuse box and we need to lift the fuse box button/switch up to turn all lights back on. but kitchen light bulbs are now broken..dont always trip the fuse box thought.. this exact same problem also happens upstairs in my room and another one we had basic one bulb light fittings in each room with basic on/off switches..still problem there. we then upgraded the odd one or 2 rooms with spot lights in some of the rooms halogen ones. problem still there.. we have even had dimmers broken because of this problem..and the dimmers were so expensive

this seems to happen on random days.. there is no pattern.

now i say im not an electrician and im not but i can fit a light fitting and switches/dimmers..done it for years with no problems..

however i have not touched a light fitting or anything in this house at this time.apart from replacing bulbs :smilielol5:

if anyone can give me any advice on what to check or you need any more info please let me no.. i cant afford to keep buying light bulbs specially the halogen ones as there expensive and when they blow it blows 2 or 3 depending how many the light fitting has.​

 

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just checked the voltage on one of the wall sockets with a multimeter and it reads 257 my multimeter is set to ACV (600/750) Uuk voltage is 240v so is my reading safe? should i test the voltage on with multimeter on a light fitting and take a reading ?

 

[malcolmsanford]

UK voltage is 230 +10% or -6% so for the top range it can reach 253v. You measured 257v which is a little high, but with an instrument that will I guess not be particularly accurate or calibrated.

If for argument sake your voltage is 257 then yes I would be doing something about this. It may be high for many reasons, , you have a loose connection on a joint outside the property from the electrical supplier, you maybe the first/second house on run and the voltage is tapped up to feed the end houses, There maybe a fault on the electrical suppliers transformer and the list can go on.

What though you need to do is establish first is that you have a high supply voltage. There really is only one way to do this and that is to call in an electrician who will check over the house and test for the voltage and other possible causes. As you are in rented accommodation you may either need to again go through your landlord who will pay for this, or not. If you rent through an agency you could go through them to pressure the landlord, if it's a private rent then you could talk to him, this part is up to you.

As for the lamps and dimmers, if you do indeed have a supply problem, cheap lamps and dimmers will blow more than expensive ones, but even top quality lamps life will be shortened on over voltage.

 

[needasparks]

My money is on the fact you are buying your light bulbs from the supermarket which tend to be the cheapest on es you can get in saying that there are types of lamp that are a rubbish design IMO and never last long like ES and SES reflector lamps and cheap GU 10 style fittings which all when they blow will simulate a fault high enough for your MCB to trip which is how it should be.
It also sounds like a multi-way fitting you mention which all turn on and off together and most lamps have about the same life expectancy so when one or two go change them all or it will feel like your always changing lamps as you forget which ones you last change. your voltage supply does sound slightly high but as said your tester may not be too accurate but showing a high voltage may mean you live quite close to where the transformer is sited for the street and may be turned up to assist a volt drop further down the line. My advice would be to try using a better brand make of lamp first from a better source of shop or possibly changing the light fitting to take a better style of lamp. There is not much you can do to a lamp to make it blow other than made cheaply or given a rough journey in transit which both apply to suppermarket jobs. There is always the possibility that the light fitting may be faulty and the lamps may be ok but the fitting loose connections giving the empression of a blown lamp. If you still have the same problems give a local sparks a call so they can look at the situation as we can only guess as not having the advantage of seeing.

 

[MarkieSparkie]

When lamps are blowing regularly the main suspects are:
1) Poor quality lamps.
2) Over-voltage, +5% over-voltage will more than halve the life expectancy of the lamp.
3) Loose connections.
4) Poor quality lamp holders, particularly batten fittings.
5) Power quality, surges, noise and harmonics can all shorten the life expectancy of the lamp.

If your measured supply voltage is correct (nearly +12% higher than nominal) then the life expectancy of your lamps is going to be approximately 3/16 of their normal life and this could be less than 200 hours (25 days @ 8 hours use per day) for ordinary incandescent or halogen filament lamps.

You may wish to get an electrician to confirm your suspicion. If so post your location and I'm sure one of the members here will be able to assist you.

When you are confident that this is the case, contact your electricity supplier and tell them that you suspect your supply voltage is high because your lamps are blowing regularly.

 

[La Poste]

It might be a daft question but why do loose connections blow lamps?

Is it something to do with arcing and the surge in current that the arc will produce?

Thanks.

 

[linuxthefish]

It might be a daft question but why do loose connections blow lamps?

Is it something to do with arcing and the surge in current that the arc will produce?

Thanks.

Try cycling a light switch a few hundred times and see if the lamp doesn't blow! I guess its something to do with the startup current...

 

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it cant be cheap bulbs as they cost me £2 each plus we have tried all sorts of bulbs to stop the problem.. very low wattage ones to the basic 100w bulbs that are hard to find all blow no matter what bulbs we use.. i live in cleethorpes if anyone is near us i am going to check all light fittings for loose connections i will say this when the lights blow its a big flash when they do if this helps

 

[a1guvner]

Wicked idea! :seeya: VPHASE, Only joking

 

[oldtimer]

OK I do work for a letting agent and I get this question a lot first of all you say light bulbs but we need a better description and yes as someone said GU10s can be the culprit why ? well it is all to do with the bulb or lamp as electricians like to call them tolerance specs for example you fit a 4 way GU10 track light fitting that comes with 4 bulbs the problem is that you switch them on and off together so all 4 bulbs get exactly the same and because of the lifespan ie a bulb may be rated for 2000 hours then on a Monday a bulb goes and the tenant resets the MCB fine but on Wednesday another goes this time the MCB is ok but on Saturday another goes and trips the MCB so Monday morning tenant phones in to report the fault of bulbs are blowing electrician is called out he cannot find anything obvious and both the tenant and the letting agent thinks there is a problem. I also had a tenant who had 12 GU10 spots fitted in the kitch and 3 fitted in the alcove got the same report but with the rider that the bulbs in the alcove dont appear to have a problem why "well I hardly switch them on came the reply"

 

[needasparks]

OP has not said what type of lamp yet but if it is GU10 type the £2 is the happy shopper ones, For a decent brand make lamp should be double that but even then its no guarentee it will last any longer.

 

[Inteificio]

No-one going to pick up on the dimming of halogens?

If your problem is purely halogens, then it might be something simple.

Halogens bulbs run hot enough to cause the filament to vaporise, the only reason then do not burn out in a few hours is the halogen cycle.

The vaporised tungsten reacts with the halogen gas making a tungsten halide. The gas varies, but bromine comes to mind (please correct if wrong).

At the filament starts to thin, following the i2r rule it gets much hotter. If not for the tungsten halide the filament would then blow.
However with gas present, the tungsten halide breaks down depositing tungsten on the hot spot effectively repairing it.

This clever repair systems has two flaws:

1: it requires a VERY precise temp
2: the depositing tends to concentrate on the middle which means the ends burn out (otherwise you would never need a new one).

If you dim a halogen make sure you dim it a LOT (effectively turning it in to a standard incandescent). If you dim it only a little bit the filament will burn, but will not get hot enough to self repair.

Dimming halogens dramatically shortens the life.

 

[oldtimer]

I forgot to add that GU10s on cartridge fuse DBs are a nightmare because the tenant does not have a Scoobie

 

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i checked all light fittings for loose wires and in one room i found 2 grey cables..and inside them two cables are wires with an earth wire.but in the other grey cable there was no earth cable..after stripping the grey cable i found the earth cable. would this cause my problems if only one earth cable was connected to the earth on the lamp ? iv now connected both earths to the lamp

 

[Marvo]

i checked all light fittings for loose wires and in one room i found 2 grey cables..and inside them two cables are wires with an earth wire.but in the other grey cable there was no earth cable..after stripping the grey cable i found the earth cable. would this cause my problems if only one earth cable was connected to the earth on the lamp ? iv now connected both earths to the lamp

This is a safety issue but it wouldn't cause the lamps to blow.

 

[WDMDL]

My opinion, without seeing anything, is that the high supply voltage is the problem.
It's not likely to be outside of the limit (253V) - but it is feasible and if verified as outside the limit, the DNO should investigate and take remedial action.

The reason lamps blow at switch-on is that (particularly with halogens) the filament has a much lower resistance when cold.
So, at the instant of switch-on, a large current flows which results in a large magnetic field around the delicate filament. It twangs violently, snapping at the weakest point.
Obviously, with a higher than normal supply voltage, the current will be higher.
Then, the resulting arc ionises the gas in the lamp - so the lamp then appears as a short circuit, the fault current causing the MCB to trip (and destroy your dimmer).

I'm generally up in Cleethorpes a lot, but don't think I'll be there in the next week or so... though I have a heating install to do on a holiday home up there in the near future.

Simon.