24-11-2015, 11:17 AM
Your supply is shared but not hugely so. Definitely single phase since there are only 2 conductors for the 11kV supply.
CNE means combined neutral/earth. So it's definitely PME except there aren't many places to have multiple earths on the neutral. It's these that minimise the risk of the neutral going nasty in the event of a fault.
The earthing arrangment appears to be using the 3rd core of the SWA as the protective earth, plus a separate 10mm for main equipotential bonding between house and outbuilding. All seems pretty sensible to me. Provided the cable armour is earthed somewhere it doesn't matter. If earthed at both ends it's contributing to the bonding.
If you decide to TT then there must be no earth connection between house and chalet.
TT is always safe but you may struggle to get the required 200R earth loop impedance using an earth rod. You may end up using an earth mat or multiple rods. Crudely the 30mA RCD has to trip if there's an earth fault, hence 230V/30mA = 7.7k earth loop impednace would work. But the regs say (I think) 200R though that's from memory. Obviously you'd be safe with well over 1k earth loop impedance in practice.
CNE means combined neutral/earth. So it's definitely PME except there aren't many places to have multiple earths on the neutral. It's these that minimise the risk of the neutral going nasty in the event of a fault.
The earthing arrangment appears to be using the 3rd core of the SWA as the protective earth, plus a separate 10mm for main equipotential bonding between house and outbuilding. All seems pretty sensible to me. Provided the cable armour is earthed somewhere it doesn't matter. If earthed at both ends it's contributing to the bonding.
If you decide to TT then there must be no earth connection between house and chalet.
TT is always safe but you may struggle to get the required 200R earth loop impedance using an earth rod. You may end up using an earth mat or multiple rods. Crudely the 30mA RCD has to trip if there's an earth fault, hence 230V/30mA = 7.7k earth loop impednace would work. But the regs say (I think) 200R though that's from memory. Obviously you'd be safe with well over 1k earth loop impedance in practice.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
