Dimmer blows when a bulb goes out

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I have a one way dimmer switch 400w which controlled a plate with 4 x GU10 50w bulbs, each time a bulb goes out the dimmer blows, it will switch off and on but not dim, obviously this has blown, WHY does it do this everytime one bulb blows, i thought the 400w rating of the dimmer switch would be more than adequate for 4 x 50w bulbs?
Please help......
 
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Because when a lamp fails it effectively becomes a short circuit, and allows a large amount of current to flow for a very short time. You may see this as a blue flash when the lamp fails.

It is this high current that destroys the dimmer. Better quality lamps and dimmers, especially soft start dimmers such as MK or varilite seem much less prone to failure in this way.
 
I used to have a problem with GU10's in my kitchen on a dimmer tripping the MCB whenever they blew. I swapped the dimmer for a switch, then swapped the lamps for LED equivalents.
Anyway, that doesn't help you but I like to ramble on.

Serious question: In your consumer unit, does the fuse blow, or the MCB (circuit breaker) ever trip when the bulb goes?
 
Some lamp have built-in fusing to try and prevent this from happening, but it is not always a dead cert.

GU10 lamps seem to cause damage every time they fail, but other lamps are prone to this behaviour too.

I always swear by Osram lamps, but they are more often available in wholesalers, not retailers.

What brand of lamp are they?
 
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It would be interesting to perform a trial using two 110 volt lamps in series. The intention being that when one lamp fails the impedance of the other lamp will limit the current to twice the normal. The duration of the double current will be very short and damage to the surviving lamp should be minimal.

Dimming halogens will shorten their life as they are then too cool for the tungsten cycle to function allowing tungsten vapour to condense on the glass. Thus the filament becomes thinner faster than it does at normal brightness.

As an aside connecting 2 230v non halogen incandescent lamps in series provides a very cosy warm light. ( not reccomended as a novice DIY project )
 
Just started looking for some ceramic G6.35 lamp holders - then I'll be able to have 7 or 8 36V 400W lamps in series.

Not sure how cosy it will be, but it'll definitely be warm :mrgreen:
 
then I'll be able to have 7 or 8 36V 400W lamps in series.

As 7 times 36 = 252 all the lamps will be running very close to their normal operating voltage so will be full brightness and not dimmed.

230 divided by 7 equals 32.85

Use 14 or 16 in series and then they will be getting half their normal oerating voltage and thus operating at approx 1/4 of their normal power which is when the warm cosy glow occurs.
 
I used to have a problem with GU10's in my kitchen on a dimmer tripping the MCB whenever they blew. I swapped the dimmer for a switch, then swapped the lamps for LED equivalents.
Anyway, that doesn't help you but I like to ramble on.

Serious question: In your consumer unit, does the fuse blow, or the MCB (circuit breaker) ever trip when the bulb goes?

Thanks for that, no nothing blows in fuse or circuit breaker, Juat when a bulb pops the dimmer blows out too, replaced twice now..
 
Some lamp have built-in fusing to try and prevent this from happening, but it is not always a dead cert.

GU10 lamps seem to cause damage every time they fail, but other lamps are prone to this behaviour too.

I always swear by Osram lamps, but they are more often available in wholesalers, not retailers.

What brand of lamp are they?

They are Newlec lamps, left behind by sparks who were working nearby, amazing what you can blag for feeding them up on cuppa's..
 
Yea I would happily give away halogen lamps, they often come with the fitting, and if you're putting LEDs in straight away, you have the halos spare
 

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