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....

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

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?

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.

Edited November 10, 200718 yr by Baracus

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......

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)

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!

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