Can faulty lamps blow dimmers?

[whazza22]

Friend of mine whats me to look at the kitchen lights.

They said that two bulbs blew which took out the mcb. They replaced the lamps and the lights work but dimmers do not.

Would the dimmers of blown?

 

[telectrix]

probably. are they halogen downlights?

 

[Marvo]

If the current was enough to trip the MCB then it was certainly enough to damage the output diac of a dimmer module. Are you sure is was just a failing bulb that caused the trip and not a wiring fault? A blowing bulb shouldn't really cause a fault current that large..

 

[Deleted member 9648]

GU10's are notorious for this,they can go with a hell of a surge,mcb's trip and dimmers are lucky to survive.......any tungsten bulb can take a 6a type b mcb out....type c's tend to help.

 

[WDMDL]

Any filament lamp can kill a dimmer as the lamp expires. Something to do with ionising the argon gas and becoming a dead short for an instant.
A couple of the remote control dimmers I have take a 1-Amp fast-acting HRC fuse - a spare is supplied with the dimmer and the instructions explain that the fuse will likely blow as a lamp fails.

Simon.

 

[Phil]

i have replaced a few dimmers due to gu10 that have blown and taken the dimmers out

 

[spsparks]

see this all the time too with filament lamps usually marked morrisons or tescos

 

[nickblake]

Yes definatly ,especially common with GU10 lamps ,what you need to do is see if you can change the lamp to a fused type these are available from most wholesalers these should protect the dimmer from damage

 

[tes11]

gu 10 deadly lol

 

[Marvo]

There seems to be consensus that this is a common problem. I've never come across this and I'm trying to picture how a bulb filament burnout could cause an overload large enough to damage a dimmer.

 

[SirKit Breaker]

Yes they can, come across this frequently, its one of the reasons that i hate dimmer switches.

 

[WDMDL]

There seems to be consensus that this is a common problem. I've never come across this and I'm trying to picture how a bulb filament burnout could cause an overload large enough to damage a dimmer.

It's what also usually trips a 6-amp type B MCB.

Getting really technical, I found this which details what i said a few posts ago:

Lamps blow, and the gas breaks down in the vicinity of the broken ends where the field is high (volts per metre being high, as we have 230V across a fraction of a millimetre, so the field can be (briefly) the equivalent of a few megavolts per metre.) The gas molecules ache under such a tension, and then give up a few electrons, but once the lamp volume has a significant number of dissociated ions in it (a plasma) It is far easier for these electrons and ions to rush directly for the metal stalks of the lamp, missing out that difficult resistive filament part, and woo-hoo - up go the amps, until the metal legs melt, or somethng trips - the blue flash you see just as the fuse trips is the plasma arc..
This onset of rapidly rising current, and the additional avalanche ionisation it generates, is known in the trade as a negative resistance

Simon.

 

[SpannerSpark]

Nice answer WDMDL. At college we were told that back in the "good-old" days british made lamps had small internal fuses which blew when a filament started to breakdown and the current spike occurred, and saved the MCB from tripping or circuit protection fuse from opening. But as these fuses added 0.01p to the lamp manufacture cost and they werent required by euro law, when lamps started being made in the far-east the fuses werent required and hence we have nuisance tripping when a lamp goes. Guess thats progress for you.

 

[nickblake]

Nice answer WDMDL. At college we were told that back in the "good-old" days british made lamps had small internal fuses which blew when a filament started to breakdown and the current spike occurred, and saved the MCB from tripping or circuit protection fuse from opening. But as these fuses added 0.01p to the lamp manufacture cost and they werent required by euro law, when lamps started being made in the far-east the fuses werent required and hence we have nuisance tripping when a lamp goes. Guess thats progress for you.

Alot of lamps these days do have fuses especially the GU10 down lighters these were introduced do to the exact same reason blowing triacs in the dimmers , you will find however the cheaper vast produced lamps do not have internal fuses