few various questions need clarity... please...

biggal5 · Jan 24, 2011

Hello All,
1st of all, gotta say that I'm new to this forum and definately find it brilliant for help and answers to my queries..
I haven't had the luxury of working with an established sparky before and have got my regs and paperwork for an electrician just recently.. I've found loads of help and answers to questions i've asked myself on this forum. However will be greatly appreciated if you can help me in these few various q's:.. Thanks in advance:

1) I've got my c.u in my cellar but want to move it to under the stairway.. The main fuse + meter etc. is all there next to it but just wanted to know if there's any limit on the length of meter tails I can have from the meter to the c.u.? I heard 3m but not sure?

2)When they say cable grouping in correction factors (Cg), how many cables do they mean? 2? more..?

3) Is it not advisable to run a circuit to an outbuilding frm the household c.u. Something I heard about not taking the main bonding off the main board?? Or have I been fed. I was thinking of running SWA from spareway in c.u to a garage unit with rcd 30mA to feed skt ring and light circuit?

4) Also recessed downlights. Alot of potential customers have asked me to replace normal pendant light to recessed dwn lgts. Is it sufficient to just cut out the hole and fish the cables through ceiling, and just pushing the insulation as far back as I can around the hole? Also are firehoods / fire rated lights ALWAYS used or just if living quarters floor above.. Just that most firehoods I see are way bigger than the spots and seem to get squashed.. (No loft space upstairs..gutted!!)

Thanks everyone.... please help.... wanna learn this right before bad habits come in.... Cheers... B.

Guest123 · Jan 24, 2011

biggal5 said:
Hello All,
1st of all, gotta say that I'm new to this forum and definately find it brilliant for help and answers to my queries..
I haven't had the luxury of working with an established sparky before and have got my regs and paperwork for an electrician just recently.. I've found loads of help and answers to questions i've asked myself on this forum. However will be greatly appreciated if you can help me in these few various q's:.. Thanks in advance:

1) I've got my c.u in my cellar but want to move it to under the stairway.. The main fuse + meter etc. is all there next to it but just wanted to know if there's any limit on the length of meter tails I can have from the meter to the c.u.? I heard 3m but not sure? 3M is the generally accepted limit that the DNO will guarantee the operation of their service fuse. Over this length and you will need to fit an additional switchfuse to protect the distribution circuit to the new CU position.

2)When they say cable grouping in correction factors (Cg), how many cables do they mean? 2? more..? 2 or more cables touching each other is 'grouped'.

3) Is it not advisable to run a circuit to an outbuilding frm the household c.u. Something I heard about not taking the main bonding off the main board?? Or have I been fed. I was thinking of running SWA from spareway in c.u to a garage unit with rcd 30mA to feed skt ring and light circuit? The main bone of contention regarding this depends on the type of earthing system present and other sevices that may be present in the outbuilding. If you do a forum search on here for 'exporting pme' you will find numerous threads on the subject.

4) Also recessed downlights. Alot of potential customers have asked me to replace normal pendant light to recessed dwn lgts. Is it sufficient to just cut out the hole and fish the cables through ceiling, and just pushing the insulation as far back as I can around the hole? Also are firehoods / fire rated lights ALWAYS used or just if living quarters floor above.. Just that most firehoods I see are way bigger than the spots and seem to get squashed.. (No loft space upstairs..gutted!!) Fire hoods are a PITA, best to use fire rated downlighters. As for the insulation, you need to get it as far out of the way as you can as if you're using halogen lamps the heat build up can be a real issue.

Thanks everyone.... please help.... wanna learn this right before bad habits come in.... Cheers... B.