New Mains Downlighter tripping fuse box don't know why!!!

[bennyboy]

Hi guys I hope you can help.

I have just installed a Mains voltage 50W downlighter into my bedroom cuboard. I have broken into the main lighting ring in the loft with a 20amp Junction box. I have a string pull switch on the ceeling with is conected to the downlighter directly. I then have another 2 core and earth 1.0mm cable from the downlighter to the junction box. The earths are bound together at the downlighter as it is doubled earthed already.

My problem is this, whenever I reapply the main fuse for the upstairs lighting ring the dowlighter is on, when I switch the light to off, then back on, the upstairs lighting ring fuse trips and all the lights go out. I don't understasnd why it is causing a trip???

Do I need another junction box for the switch and the cable from the downlighter, sorry for being long winded, dont know how else to explain it!!! PS I have already tried the above with a 5 amp junction box where I have broken into the lighting mains.

Cheers

Ben

 

[dingbat]

You have created a short circuit whenever you switch on. This is probably the single most common DIY screw up associated with lighting. Did you use a three terminal junction box, by the way? You'll need one with four terminals. Go to the 'Electrics UK' section in the forum and read the post at the top, called 'For reference'.
If, after you've read the entries and studied the diagrams, you don't understand, then call in an electrician.

 

[bennyboy]

Thanks for the advice i'll have a good look at that now!!