martyn_16v
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| posted on 16/12/08 at 08:56 PM |
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Electrical advice needed
I was hoping a couple of the friendly sparkies here could point me in the right direction, or at least tell me what a blinding idiot i'm being
A couple of retail units I look after are having stud walls pulled down and put up in slightly different configurations, and as a result muggins here
has to do the electrics donkey work to save a bit of money on the projects. I just need a couple of bits confirming really...
Unit 1: This one is the simpler of the two. It's a relatively recent electrical install (2007). I'm just removing one ring main circuit,
and when the work is done refitting all the socket outlets about a foot higher.
The current setup is a ring main contained in surface mounted PVC conduit, using 2.5mm2 single cables (blue brown & green/yellow). Runs off a 32A
type B MCB. The entire consumer unit is protected by a single RCCB main switch.
Can I just put it back exactly as it was (give or take a couple of cables extended by a foot or two), and then get it installation tested? Is it
likely to meet 17th edition?
Unit 2: Similar story, but an older electrical installation. The existing stuff is all in the old wiring colours, ring main circuits in 2.5mm2 single
cables in PVC box trunking. There is no RCD protection at all in the consumer unit, it's all MCBs.
Presumably I'd need to replace the MCBs in the circuits i'm moving with RCBOs.
A colleague has mentioned that he thinks the 32A ring circuits need to be replaced by radials (with 4mm2 cable) for 17th edition, but I'm not
sure?
Thanks in advance,
Martyn
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Liam
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| posted on 16/12/08 at 09:19 PM |
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Only really read up on regs related to domestic installations, as I'm doing a rewire in my new (very old) house so can't comment much off
the top of my head. I will say the supposed requirement to replace ring mains with a radial with beefy cable sounds like a load of bollo**s.
Er hope that helps.
Liam
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martyn_16v
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| posted on 16/12/08 at 09:23 PM |
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Yeah I haven't seen or heard about rings being a no-no anywhere else, but you know what it's like when someone puts a niggling doubt in
your head 
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Liam
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| posted on 16/12/08 at 09:33 PM |
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Meant to add...
Post the question on the electrical section of the DIYNot.com forum. It's an excellent forum and you will be answered very quickly by very
knowledgable people!
Liam
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YQUSTA
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| posted on 16/12/08 at 10:21 PM |
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Been a while since I was a sparks but still do a little so here we go best guess.
Unit 1 as you say should be fine but I would prefer it if you replaced the cable as i'm not to sure how your going to extend it but using proper
juction boxes would be fine just not the best way of doing it as there is too mush to go wrong.
unit 2 is a bit of a bugger it will need the new circuit/s doing in the new colours,
what I cant remember is if you will need to fit a new consumer unit with rcd protection even a small 1 just for those circuits.
A label will hve to be visable stating that the wiring is in 2 different colours usually placed on the fuse box.
As I say been a while since I was a sparks.
And on another note far more important to yourself is if this work you do causes a fire or anything else the H&S will hold you accountable not the
guy who comes to test it so if i were you i would take that into consideration.
YQUSTA
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t16turbotone
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| posted on 16/12/08 at 10:29 PM |
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right......you will only be altering exsisting circuits so as long as you alter correctly and GET IT TESTED PROPERLY....no problem...if you have a
consumer unit with rcd /mcbs thats fine...your not expected to upgrade to the 17th just because youve moved a socket, date of origonal installation is
a big factor.
the 17th is a better set up, basically rcbos for every circuit, and radial circuits because ring mains are shit, and the 4mm radial much better for
many reasons...however i would implement rcd protection on socket outlets in unit 2 as a minuim requirement
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