10-10-2012, 08:24 PM
(10-10-2012, 02:31 PM)pwdrive Wrote: That Dr Mark is a smart fella, wonder what he thinks...
That's very kind of you, but not entirely accurate
I read up on this a little bit - a few years back when planning my workshop. Unfortunately, kids, work and house renovations have put my plans for that on hold :-(. I've got TN-S, so my conclusions were different anyway...
The really lazy answer to this would be "get an electrician in, as what you're doing is notifiable work". Probably not what you want to hear!
Regarding colours, with the 3-phase SWA, it seems to be up to you to decide. Marking each end with coloured tape (or heat-shrink, because we are professionals
) is obviously very sensible. Some interesting views on here:http://community.screwfix.com/message/1170467As you have PME (or TT), your earth loop impedance is quite high. For that reason every circuit should be RCD protected. The SWA cable should be protected by an RCD in the house. For convenience, it's best to use a separate one so that a fault outside doesn't take out the entire house. It's bad enough that an outside fault will require you to walk back indoors, but by careful choice of RCD trip rating/times, you can hopefully design out the more inconvenient scenarios...
As to exporting the earth, I think that opinions vary enormously, which rather suggests that the regs are written in an ambiguous way. Without thinking too hard about it, I think that my instinct would be to not export the earth and use an earth spike at the external site. The upstream RCD assures safety. But I can see that it's not a straightforward choice...
All the best,
Mark
