Baracus Posted November 10, 2007 Share Posted November 10, 2007 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. Thats actually incorrect. if you work out the earth leakage for 6 Desktop towers and 6 CRT Monitors it is a lot less than 30mA. When Tony Blair decided to splash the cash and spend millions on computers for schools it was standard spec that no more than 6 twin sockets should be wired to a 30mA RCBO. Ive always stuck to this rule and never had a problem - literally thousands of circuits later.... Link to comment Share on other sites More sharing options...
Baracus Posted November 10, 2007 Share Posted November 10, 2007 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. Thats true but most house wiring is run horizontally or vertically to an accessory or consumer unit therefore METAL protection is not needed Link to comment Share on other sites More sharing options...
luggsey Posted November 10, 2007 Share Posted November 10, 2007 Thats true but most house wiring is run horizontally or vertically to an accessory or consumer unit therefore METAL protection is not needed Yeah in a zone with less then 50mm I'm talking about..... As for the CRT/PC tripping RCD's I had a local school that used to turn off the RCBO "big switch" after lessons to stop PC's being used. When the switch was flipped on again six CRT's and six PC's all powering up at the same time plled the RCBO every time. If you look at the surge of six CRT's firing up together it's pretty big, in fact enough to cause problems on the job I looked at, depends if the CRT's power up looking for a vid signal dosen't it? ----------------------------------------------------------------------------------------------------------------------------------- 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...
Baracus Posted November 10, 2007 Share Posted November 10, 2007 Yeah in a zone with less then 50mm I'm talking about.....As for the CRT/PC tripping RCD's I had a local school that used to turn off the RCBO "big switch" after lessons to stop PC's being used. When the switch was flipped on again six CRT's and six PC's all powering up at the same time plled the RCBO every time. If you look at the surge of six CRT's firing up together it's pretty big, in fact enough to cause problems on the job I looked at, depends if the CRT's power up looking for a vid signal dosen't it? Fair point, a lot of the key switches were done away with most likely because of this. Steel conduit is definitely not needed when run horizontally or vertically from an accessory or consumer unit regardless of depth thou. Link to comment Share on other sites More sharing options...
luggsey Posted November 10, 2007 Share Posted November 10, 2007 Thats true but most house wiring is run horizontally or vertically to an accessory or consumer unit therefore METAL protection is not needed Ok I'll try to clear this one up, if you run a cable in a celing or a wall at a depth of less then 50mm it has to be an earthed jacket type cable, or in conduit suitable to stop a nail. I made the point that if you wire in a "zone" the 50mm rule does not apply.... 522-06-06 i-iv It's interesting that BS 7671 applies to all wiring systems including intruder...... ----------------------------------------------------------------------------------------------------------------------------------- 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 10, 2007 Share Posted November 10, 2007 Ok I'll try to clear this one up, if you run a cable in a celing or a wall at a depth of less then 50mm it has to be an earthed jacket type cable, or in conduit suitable to stop a nail. I made the point that if you wire in a "zone" the 50mm rule does not apply.... 522-06-06 i-iv It's interesting that BS 7671 applies to all wiring systems including intruder...... is the zone still down the corner within 150mm and then across ( or was that a bad pie I once eat giving me horrendous dreams) Link to comment Share on other sites More sharing options...
luggsey Posted November 10, 2007 Share Posted November 10, 2007 is the zone still down the corner within 150mm and then across ( or was that a bad pie I once eat giving me horrendous dreams) Yep, vertically or horizantally from any accessory and 150mm in the corners which I think is utter bollox BTW! ----------------------------------------------------------------------------------------------------------------------------------- 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 10, 2007 Share Posted November 10, 2007 and 150mm in the corners which I think is utter bollox BTW! so right where I`m going to be drilling monday then - sparks LOL Link to comment Share on other sites More sharing options...
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