Rocboni
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- Reaction score
- 145
Recently our family friends had a supply installed in there winter yard (travellers/showmen), being a trainee and having just covered special locations section 708 at college,I was interested to see how it Was done.
Supply is as follows.
3 phase TNS supply
25mm tails to 63A 4 pole switch fuse
20M run externally 16mm 4 core supplying TPN 4way board located in the centre of the yard (swa as earth)
Located in TPN board
6x 32A RCBO each supplying a 32A outlets via a meter for individual caravans
2x 32A mcb feeding a 40M 4 core 10mm to a second box with 2x16a 2x32A sockets
Arrangement of second box
1x32A and 16A one each phase with its own neutral through a 32A kWh meter 32A skt protected by 20a RCBO 16A skt protected by 16A RCBO. This box is TT with the armour of the 10mm earthed via the TPN board but isolated from this box. 3 earth rods linked via 16mm each anout 2M apart.
My understanding is that all supplies For caravans should be TT so my question is should the first TPN board be TT? however it would be difficult to locate rods as where box is located is concrete but caravans stand on gravel so this is possibly why they did not TT the supply?
Second question is it ok to run two single phase circuits in one cable protected by two separate MCB no shared Neutral as the 4core is L1 L2 N N
Some of these caravans are the size of acrid trailers but I guess it would still come under this section of the regs?
Supply is as follows.
3 phase TNS supply
25mm tails to 63A 4 pole switch fuse
20M run externally 16mm 4 core supplying TPN 4way board located in the centre of the yard (swa as earth)
Located in TPN board
6x 32A RCBO each supplying a 32A outlets via a meter for individual caravans
2x 32A mcb feeding a 40M 4 core 10mm to a second box with 2x16a 2x32A sockets
Arrangement of second box
1x32A and 16A one each phase with its own neutral through a 32A kWh meter 32A skt protected by 20a RCBO 16A skt protected by 16A RCBO. This box is TT with the armour of the 10mm earthed via the TPN board but isolated from this box. 3 earth rods linked via 16mm each anout 2M apart.
My understanding is that all supplies For caravans should be TT so my question is should the first TPN board be TT? however it would be difficult to locate rods as where box is located is concrete but caravans stand on gravel so this is possibly why they did not TT the supply?
Second question is it ok to run two single phase circuits in one cable protected by two separate MCB no shared Neutral as the 4core is L1 L2 N N
Some of these caravans are the size of acrid trailers but I guess it would still come under this section of the regs?