Light Spur - Help needed! Ask questions and find answers to many subjects relating to electrics and electrical work

[Stanny]

I recently fitted a new light spur to an existing light in the garage; I ran 2.5mm 2 core & earth from a new junction box in the incoming cable from the house, ran it to the switch and from there to the pendant light. When I turn the power back on all is fine when the new light is on, but when I turn it off it trips the light circuit. I checked all wiring and connections and all is fine - any ideas?

[ericmark]

I can’t of course see what you have done wrong to cause the trip to open but there are a few issues the first being a pendant light from a standard ceiling rose is normally ratted at 6 amp maximum so there should be some limiting fuse in the circuit. It is common to use a switched fused spur unit to power lights in cases like this rather than a simple switch. With house wiring the fault you relate is normally caused by getting neutrals and switch wires crossed in the ceiling rose and basically the light is on all the time and the switch causes a short so trips it out. But in your case this may not be valid if using a double pole switched fuse spur. So sorry can’t really help much. Maybe what I have said has given you ideas though?
Eric