Exploding Dimmer

[Damocles]

Hi guys.

Just fitted a new 400W IQ dimmer as replacement for a light switch. Immediate result was a smell of burning. On investigation inside the black plastic back cover discovered burned resistor and cracked diode.

No MCB trip. Replaced light switch and all's well. Load was 4 50W mains halogen downlighters.

Suggestions?

 

[andy]

did the lights come on when it was burning?

EDIT: could have been a dodgy switch since the old 1 works

 

[Damocles]

Can't say for sure since I was elsewhere switching the power back on. No sign of light when I got back to it

 

[ban-all-sheds]

Suggestions?

Take it back and get a refund.

 

[Damocles]

When I took the back off and stared at it closely I saw this broken diode. Not the big black rectifier diode, but a glass with red stripes signal or zener. Not easy to tell which since the body of it was shattered.

Odd thing about it was that the lead in wires either end were not pointing towards each other. Both were pointing downwards towards the circuit board. Not so much as to be completely incredible, but rather odd. It would not really expect the blast from an exploding diode to push the end wires down like that, but perhaps they could. The other explanation might be that it was already crushed before it was assembled. No sign of damage to the back cover. (except a bit of melting from the burnt out resistor)