JohnCunningham Posted November 9, 2007 Share Posted November 9, 2007 Hello all It's my first post! If the earth cpc (earth wire on the T&E cable in old money) is not connected back to the main fuse board and hence "earthed " itself the earth wire sitting between the L&N acts as a center tap capacitor (apparently). I found this out after measuring up to 120V on the cpc of a lighting circuit without the cpc's linked in any way. The voltage varies with cable legnths but doesn't seem to get above 120v. Odd but true. I spent a while testing and all Insulation resistance of all conductors 200M + and there were no other cross overs. NICEIC help desk had no answer but found an IEE paper on it somewhere on the internet. Hope this helps John Link to comment Share on other sites More sharing options...
Baracus Posted November 9, 2007 Share Posted November 9, 2007 There are several now with internal fuse, I think they had to start installing fuses after so many problems from them, blown dimmers, tripped MCB's etc.But most will still fit the el'cheapo ones! All I use is Osram a lot cheaper in the long run! Link to comment Share on other sites More sharing options...
Baracus Posted November 9, 2007 Share Posted November 9, 2007 . NICEIC help desk had no answer Well thats only to be expected ! Link to comment Share on other sites More sharing options...
Paul P Posted November 9, 2007 Share Posted November 9, 2007 during an alarm service last night I tested the 240v and got the followingL - N 240v N - E 170v L - E 70v obviously adviced the customer to get an electrition(sic) in as a matter of urgency (ie straightaway) what could have been wrong? and should I have powered them down? You obviously have no earth at the control panel, if its metal then yes it should be powered down as the case will be at 170v. Trade Member Link to comment Share on other sites More sharing options...
Paul P Posted November 9, 2007 Share Posted November 9, 2007 good sparky wouldnt put the lights ( or the freezer GRR ) on the RCD side - well except they now stuffed that too with the 17th edtn I think you are only looking at the down side of the 17th edition on RCD Trade Member Link to comment Share on other sites More sharing options...
luggsey Posted November 9, 2007 Share Posted November 9, 2007 Hello all It's my first post!If the earth cpc (earth wire on the T&E cable in old money) is not connected back to the main fuse board and hence "earthed " itself the earth wire sitting between the L&N acts as a center tap capacitor (apparently). I found this out after measuring up to 120V on the cpc of a lighting circuit without the cpc's linked in any way. The voltage varies with cable legnths but doesn't seem to get above 120v. Odd but true. I spent a while testing and all Insulation resistance of all conductors 200M + and there were no other cross overs. NICEIC help desk had no answer but found an IEE paper on it somewhere on the internet. Hope this helps John How interesting! I'll try that when I get chance, . ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum Link to comment Share on other sites More sharing options...
Guest anguscanplay Posted November 9, 2007 Share Posted November 9, 2007 I think you are only looking at the down side of the 17th edition on RCD Link to comment Share on other sites More sharing options...
JohnCunningham Posted November 10, 2007 Share Posted November 10, 2007 I went to a free NICEIC seminar about the 17th ed the other night. It seems that RCDs are the order of the day. Although not set in stone yet. we were informed that all wiring not 2" deep into walls would have to be protected by nail proof means if not in safe zones and if safe zones would not have to be protected but covered by 30 Ma rcd. This means all light drops have to be covered by an RCD to my understanding. All (everywhere) sockets that can be used by ordinary people would have to be RCD covered (not just to be used outside). Although you can have some non rcd sockets if they are labelled for that use only such as computer rings where earth leakage a problem and possibly a freezer circuit if you manage to comply somehow with all the other requirements. We had a discussion about RCBO route and split RCD/RCD boards. Either way is a tad more pricey. I was hoping to get away with the rcd spur idea in bathroom ceiling on the rentals I test but looks that may not be the case. But then It hasn't been signed off yet so may all change. John that was the point I was making Link to comment Share on other sites More sharing options...
Baracus Posted November 10, 2007 Share Posted November 10, 2007 we were informed that all wiring not 2" deep into walls would have to be protected by nail proof means if not in safe zones and if safe zones would not have to be protected but covered by 30 Ma rcd. That always made me laugh, by the time you track 3 inches into a wall there wouldnt be much left apart from an angry builderAll (everywhere) sockets that can be used by ordinary people would have to be RCD covered (not just to be used outside). I always fit an RCD/RCBO for sockets regardless of location Although you can have some non rcd sockets if they are labelled for that use only such as computer rings where earth leakage a problem I never put any more than 6 computers on a ring there shouldnt be enough leakage to throw a 30mA Link to comment Share on other sites More sharing options...
luggsey Posted November 10, 2007 Share Posted November 10, 2007 That always made me laugh, by the time you track 3 inches into a wall there wouldnt be much left apart from an angry builderI always fit an RCD/RCBO for sockets regardless of location I never put any more than 6 computers on a ring there shouldnt be enough leakage to throw a 30mA In the "old days" if six PC's had six CRT monitors and they all power up when the big switch is turned on they always seem to trip RCD's, not a problem now with TFT IMO. The rule about 50mm of protection for burried cables has always been known, if less the 50mm you need earthed metalic protection against nails, I always think if you wire in a "zone" then that should be ok without metalic protection as to be honest most house wiring is less the 50mm deep as already mentioned. RCD's are going to be almost standard for all sockets in houses in the 17th, and all bathroom wiring, a good thing IMO. As to fridges, cut off the plug and wire to a spur, fixed appliance then not requiring an RCD, voids the warrenty on the fridge though! ----------------------------------------------------------------------------------------------------------------------------------- Life is like a box of chocolates, some bugger always gets the nice ones! My Amateur Radio Forum Link to comment Share on other sites More sharing options...
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