DIY Doctor


Postby qm203 » Sat Nov 08, 2008 6:14 pm

I have installed a set of 5 halogen dimmable downlights in bedroom, all lights work ok but the fuse trips when i switch them off!!!
I have changed the switch for a dimmer type now they stay on! and wont switch of a all, can anyone help
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Simply Build It

Postby ericmark » Sat Nov 08, 2008 8:25 pm

Please remember this is a lot of guess work but here goes.
You have connected the switch wire which may be same colour as neutral to the neutral cables and when you switched on the light it caused a short circuit and tripped the MCB.
When you fitted a dimmer switch the direct short circuit has blown the semi-conductor devices and so no longer causes a short circuit so lights continue to work.

So am I anywhere near? The switch wire should be two line coloured cores but most twin and earth has one line colour and one neutral coloured core. So a line coloured sleeve is used over the neutral coloured wire. But it is easy for these to fall off which means one has a line wire with a neutral colour.

Both in projects and on my own web page there are diagrams as to how lights are wired as standard.

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