Workshop lighting problem

[jpt]

My workshop electrics runs from its own dedicated 30amp supply from the main fuse board to a basic fuse box in the workshop without any trips installed in it and then to the various circuits.

Yesterday when I turned the fluorescent lights off it tripped the 30ma trip in the main fuse box and it has done the same thing today. Before I call in an electrician I was wondering if anyone could tell me what might be the cause please.

john

 

[Togalosh]

Hi jpt,

..a duff switch?

It'd be cheap & easy to replace so you'll not really lose out if it's not it.

 

[9fingers]

Do tell how a doggy switch will trip an RCD??

 

[Elapid]

Not got much electrical knowledge but could it be damp or water in the light or switch causing it to short out?

 

[Grahamshed]

Not got much electrical knowledge but could it be damp or water in the light or switch causing it to short out?

I was thinking along similar lines but wouldn't that cause it to trip when turned ON rather than OFF ?

 

[Togalosh]

I will stop posting replies before engaging my brain...

 

[DTR]

As it's the RCD that's tripping, and as it's only tripping when the lights are turned off, I would guess that it's one of the chokes dumping something into the circuit. That's purely a guess though.

If the lights can be individually isolated then you could try each one at a time and find which one is the culprit...

 

[Tom K]

How many lights on the switch? My guess would be a fault in one of them. I would check by removing covers and taking them out of the circuit one at a time.
There is sometimes scorching and expansion when the internal componenents are going bad accompanied by an unpleasant aroma. Certainly check out the switch as your first port of call even if only to mentally cross it off. I lived in a house where the fuses popped every time a bulb went not quite the way it should have worked i'm sure. Bob can undoubtably give some expert analysis once the donkey work is done.

 

[DTR]

Just noticed that you said it trips the RCD at the house. Is it possible to visually inspect the cable between the house and the workshop?

 

[jpt]

Thank you for the suggestions but I think I have cured the problem.

It was tripping out every time I turned the lights off so when I tried it first thing this morning it tripped out so I then removed the fuse from the main box so the workshop was isolated. I then took the front cover of the light switch off to check it and it was dry but a bit dusty so I used an airline to clean it out checked the connections were tight and put it back together. I then took the cover off of the fuse box in the workshop and it was a bit dusty inside. So I unscrewed the main cover and it was quite dusty but no sign of burning or tracking so I cleaned it out and checked all the connections were tight and put everything back together. I then put the fuse back in the main box and turned the workshop lights on and off again and it didnt trip the breaker. I have turned them on and off several times since and so far no problem so hopefully it is now OK but I still dont know what was causing it.

john