Fuse tripping with new downlighter

[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]

Like I said in General DIY - read the 'for reference' post!

 

[plugwash]

sounds like you have connected the switch accross the supply a typical newbie mistake

if your junction box has 4 terminals i would take the cable from the switch there and wire it like a ceiling rose (as seen in the for reference section)

 

[TexMex]

sounds like you have connected the switch accross the supply a typical newbie mistake

But he says in his post.

whenever I reapply the main fuse for the upstairs lighting ring the dowlighter is on

Surely if this was the case, when he "reapplied the main fuse" it would "trip" straight away.

 

[bennyboy]

Hi actually have the switch cable in with the downlighter cables, should I then move it up to where I have cut into the mains with a junction box and treat the empty forth pin as the sw as per a celling rose?

 

[plugwash]

yes

 

[bennyboy]

Thanks pugwash i'll give it a go!!

 

[bennyboy]

Ok thanks thats now working, I put the Switch cable (black) with the live of the light cable. Then connected all the other as they should be. Thats correct isn't it?

PS The instructions where talking about using a 5amp fuse, but i'm using a 20amp junction box does that matter?

Ben

 

[plugwash]

an oversized junction box is not a problem

as long as the fuse/breaker at the CU is of a suitable size 5A/6A

 

[bennyboy]

Yes it is, thanks for your help.