Metal dimmer switch

[Freddy86]

I'm not an electrician but I know basics. I tried to wire a dimmer switch in one of my bedrooms and I had a problem.
I turned off the power and removed the switch face and had 4 wires; 2 red, 1 black and the earth to the back box.
I terminated the 2 red in L1 and the black into COM. I also added a small earth wire from the switch face to the back box as it said it had to be earthed as it was metal. Turned the power back on and the light worked on/off but didn't dim. Then after about 5 minutes it tripped and would not go back on. So I placed the old plastic switch back on and it worked.
Why did the switch trip? Was my wiring wrong? The bulb was a energy saving one. Thanks. [/u]

 

[riveralt]

I would have expected the two red to go in the com terminal and the black in the L1 terminal - earth appears correct.

If the way you have wired the dimmer was the same as the wall switch then remember that the wall switch can work in both directions - just means the switch is actually upside down.
But that doesn't normally apply to a dimmer.
I hope you haven't bust your dimmer but you might want to try the wiring as I suggest.
Some dimmer ranges are too low for an energy saving lamp - try it with a normal incandescent lamp.

 

[mikeyd]

What tripped?

 

[Freddy86]

I wired it exactly the same as the old switch (except for the earth).
The whole power to the house goes off.

 

[sparkiemike]

Is the CFL (low energy lamp) dimmable, you have to get a lamp (bulb) that is dimmable - the ones you get from the supermarkets or diy stores are quite often not dimmable?

It is possible you have now damaged the dimmer and/or the low energy lamp.

As suggested try a normal incandescent lamp first, if that works then get a dimable low energy lamp


If it trips with a normal incandescent lamp if it continues to trip then you have a wiring fault that requires further inspection and testing.

 

[sparkwright]

Are you certain you wired it the same?

Is (or was) there two way switching in the bedroom?

 

[sparkwright]

If you do need a new dimmer switch, buy a plastic face plate one, and remove the module and fit to your metal plate. Should be cheaper.

 

[riveralt]

I wired it exactly the same as the old switch (except for the earth).
The whole power to the house goes off.

Well then as I said before your old switch was wired upside down.

Convention says your new dimmer should have been wired with the live loop (two red wires) in the common and the switch live in the L1.
Did you follow the manufactures instructions for the dimmer?
Because most dimmers have electronic controls that require the wiring to be connected specifically to that particular dimmer switch.
The power to the whole house goes off because you're installation is probably additionally protected by one RCD covering all the circuits.

 

[alexbilly2012]

Hi , I am not a electrician but speak through experience that energy saving bulbs that take a few seconds to alight are no good for dimmer switches as when I fitted a dimmer before it actually said it on the instructions , have you tried a normal bulb ?

 

[radweld]

I would have expected the two red to go in the com terminal and the black in the L1 terminal

The instructions (for MK dimmers at least) show the live to L1 for 1w switching (but to C for 2w switching).

earth appears correct.

Would be better if the earth wire connected directly to the face plate.

 

[riveralt]

I would have expected the two red to go in the com terminal and the black in the L1 terminal

The instructions (for MK dimmers at least) show the live to L1 for 1w switching (but to C for 2w switching).

But that is the way he wired up this dimmer and it didn't work - so either the wiring is wrong or the dimmer is/was bust.
Each manufacturer seems to be making their own rules - look at the bottom of the page on wiki - here
//www.diynot.com/wiki/electrics:lighting:two_way_lighting
The tilde sign with the up arrow is the Common here and yet on some dimmers that sign acts as the SL.
Which is why I said..

Convention says your new dimmer should have been wired with the live loop (two red wires) in the common and the switch live in the L1.
Did you follow the manufactures instructions for the dimmer?
Because most dimmers have electronic controls that require the wiring to be connected specifically to that particular dimmer switch.

Would be better if the earth wire connected directly to the face plate.

Not sure what difference that will make and again will be determined by the MI's.
Better to leave the existing earth wire in place, especially if there is insufficient slack and do what the OP has done and connect fly lead from the from the backplate to the switch.

 

[johnnykc]

was it a dimmable energy saving lamp?

the simple answer to that question will go a long way to explaining your situation......

 

[radweld]

Each manufacturer seems to be making their own rules

So not really any 'convention' then. As you say, need to follow the manufacturer's instructions.

Better to leave the existing earth wire in place, especially if there is insufficient slack and do what the OP has done and connect fly lead from the from the backplate to the switch.

Indeed. Though alternatively, may be better to wire to the faceplate and drop the flylead if space is tight in the backbox.

 

[Freddy86]

I don't think it was a dimmable light switch no but I took the bulb out and the power was still tripping out.

So could my wiring have been wrong? Should I have had the 2 red in COM and the black in L1? There was also a L2 terminal on the switch should I have maybe terminated a red wire in there?

The instructions for the switch where pretty confusing, the only info I gained was that it had to be earthed.

 

[Freddy86]

Dimmerable energy saving bulb*