Light fitting keeps tripping MCB.

[pashek]

Firstly, I'm sorry if I use the wrong terminology during any of this post. If you need clarification please ask.

I have replaced my standard light fitting with a flexi track system which uses a 200W transformer. I believe I have fitted it properly but when the light is switched on it will often trip the RCD (Fuse box?). This seems quite random and I can turn the light on up to 20 times before it trips. Should I just check my connections or is there something else I might consider?

Thanks

 

[sparkybird]

Hi Pashek

Are you sure it is the RCD that it is tripping? Or is the fuse (mcb) of the lighting circuit? RCD trips are more to do with earth leakage and fuse trips are generally caused by short circuits.

Your first port of call would be to check the connections, both in the light and the switch (they may have been loose to start with). Let us know how you get on

SB

 

[pashek]

Thanks for that, I knew my terminology was off. It is the MCB of the lighting circuit tripping, thank you for clearing that up. I will recheck the connections on both the light and switch, although as it was the light fitting I replaced it is most probably there that that problem lies. I will let you know how I get on.

*UPDATE* I have now checked the wiring and believe that all is secure and correct but the problem still exists. Can someone explain why the MCB only trips every so often as that is something I do not understand. Surely it should trip every time or not at all?

 

[Steve]

What sort of transformer is it? I'm thinking it could be tripping due to inrush currents. Ask an electrician to fit a type C MCB in your consumer unit. These will hold up on the high inrush currents.

 

[RF Lighting]

I was thinking the same as Crafty.

Was the transformer a heavy lump of iron with copper windings, or a little lightweight electronic transformer?

It is not uncommon for a 200VA wire wound TX to trip a 6A type B MCB.

 

[pashek]

It's a pretty big copper wound lump of iron. This being the case I will look into getting a new MCB. Is this something I could do myself or should I get someone in to do it?

 

[Steve]

Ask an electrician to fit a type C MCB in your consumer unit. These will hold up on the high inrush currents.

You need to get a spark to do it because there are a couple of tests he must do before upgrading the device, to ensure the integrity fo the circuit.

Or see if you can source and fit an electronic transformer (though this is often tricky in pre-made light fixtures and can void guarantees).

 

[scousespark]

Is the MCB tripping as soon as you switch the light on, or is it working for some time then tripping? MCBs trip for a purpose and you should get to the source of your problem before making changes. Putting in a Type C may cure the problem, but it may hide the cause.

 

[Spark123]

It sounds like the cause is the inrush current to the transformer as it isn't happening all the time and sounds like only when it is switched on.

 

[scousespark]

But the op says it doesn't happen evry time the light is switched on. Needs a check on the circuit as it's a bit difficult advising without seeing what's going on.

 

[pashek]

Thanks for all the input. Just to clarify, the MCB trips as soon as the light is switched on, there is no delay. However, as stated this does not happen all the time and there seems to be no logic behind the tripping (Tested with other lights on/all lights off etc).

Could someone indicate roughly what I need to get done and how much it may cost? I may just put back the original fitting and leave it all until after Christmas.

Thanks

 

[ricicle]

A transformer will not always take a large inrush current every time, it just depends whereabouts on the sinewave that it was switched on

 

[pashek]

Thanks, this explains why it is so random. This info has all been really helpful, thanks.

Again, any ideas roughly how much it will cost to replace the MCB?