Dimmer alive but not working

I hope the thing hasn't died...

I have 2 dimmer modules (L5508D1A) powered from the mains via CU MCBs then locally via individual isolation switches, so if I need to do something to a circuit on 1 dimmer, I can just isolate that one.

The common earth and neutrals are also separated. The 2 dimmers are electrically totally isolated from each other.

Yesterday, I powered off both dimmers so I could adjust a light fitting without zapping myself.

When I turned the power back on, one of the dimmers came back to life but the lights attached to it don't work. The dimmer the light I adjusted still works fine.

There is power to the "dead" dimmer and Toolkit identifies the dimmer and all appears to be OK. The local switches on the dimmer unit also light up/turn off when pressed but the lighting circuits do not work. I have also noticed that the buzz the dimmers make as they ramp up to full power is not happening.

It seems like the power outputs are having problems... has anyone experienced anything like this? Any suggestions? Is there any way (other than electrical circuit testing equipment, which I will try...) to analyse the output from software that I'm missing?

Any help will be greatly appreciated.

Cheers

Dave.

 

Is there 240 volts at the 'control' side (LHS) and the 'output' side (RHS) of the dimmer unit.

Sounds like yo may not have the "output" side voltage.

Grant

 

Thanks. In an odd sort of way, I think you might have been right...

I just found my multimeter and started playing around with the local switches on the dimmers.

At first, all circuits were reading 230-240V with the circuit off!

Then, when I tested the CBUS power supply end, which is powered by a live & neutral linked off the output unit power, there was a blue sparky glow/buzz (v. low frequency) from the CBUS PS neutral. I was testing by pushing the probe into the terminal screw.

I did this again with a circuit switched on locally and guess what... the light came on! Waggled the terminal a bit, powered down and it's now working again.

I assume the connection for the neutral back from the common rail somehow managed to loosen (without outside assistance!) and this broke the circuit.

Very odd but for now, fixed and I am happy again.

 

We try our best!

Just be VERY careful of dimmers. they do not isolate the 240 volts on the outputs EVEN WHEN THE LIGHTS ARE OFF!!!

If you are unsure there are many threads in this forum about it, just use the search tool.

Grant