new lights in loft

claude76 · Posted: Tue Jun 05, 2007 12:10 pm Post Subject: new lights in loft

hi first post.i have used a junction box into existing light switch wire in my loft and taken new wire fron juction box two a new two way switch.i wired in the feed from the juction box L1 RED L2 BLACK AND EARTH TO OTHER ONE.when it comes to wire in the new light wire i just put them in the same way.the light comes on when switched mains back on but when i switch the light of at the new switch it trips the fuse in main box.i tried red/blue/black/red and the EARTHS together but this just tripped as well anyone any idea what im doing wrong.

davy_owen_88 · Posted: Tue Jun 05, 2007 12:14 pm Post Subject:

You don't put neutrals into a single pole light switch...

See here:

Steve · Posted: Tue Jun 05, 2007 12:29 pm Post Subject: Re: new lights in loft

claude76 wrote:

hi first post.i have used a junction box into existing light switch wire in my loft

Erm, this is ringing alarm bells already.

A light switch wire contains live and switched live. No neutral.

claude76 · Posted: Tue Jun 05, 2007 12:52 pm Post Subject:

ok lets try this what if i wire the new light straight into the juction box i was talking about i have wired it red to live blue neutral and green earth the light comes on but is very dim and so is the one in the bedroom which is the wire in the juction box i put in loft is there a different way it gets wired.the light in the bedroom is always on this way.

Spark123 · Posted: Tue Jun 05, 2007 4:53 pm Post Subject:

It sounds like you have cut into a switch wire. The only thing you can do with this cable now is repair it, if you use the junction box to make it good, leave the JB accessable.
You'll need to find a supply cable, can you see any other cables going to the bedroom light etc?

Steve · Posted: Tue Jun 05, 2007 5:02 pm Post Subject:

claude76 wrote:

ok lets try this what if i wire the new light straight into the juction box i was talking about i have wired it red to live blue neutral and green earth the light comes on but is very dim and so is the one in the bedroom which is the wire in the juction box i put in loft is there a different way it gets wired.the light in the bedroom is always on this way.

You have no idea how lighting circuits work. The main thing to note is that black/blue IS NOT ALWAYS NEUTRAL.
See the wiki for more info/diagrams