New electricity connection

[Bitpipe]

We did pretty much everything described above but in our case we were moving supply from the still occupied but soon to be demolished house to a new kiosk and also running power to container / site office and caravan.

 

Kiosk is now jam packed with CUs and fused switches to house and garage, external sockets and drives gate controllers and lights etc. Sadly it's not in an optimal location now we've removed the trees that were behind it (planned to keep them but they died) and have landscaped around it. Just need to plant a shrub either side of it now so we don't need to look at it

 

 

 

[scottishjohn]

2 hours ago, ProDave said:

Just use 2 core SWA for the caravan.

I,m not a sparky , but to me more earthing is good 

so

 

why would you not run 3 core SWA to van and then fit and earthing rod and connect it to the earth wire in the SWA

 please explain why 

[Bitpipe]

1 hour ago, scottishjohn said:

I,m not a sparky , but to me more earthing is good 

so

 

why would you not run 3 core SWA to van and then fit and earthing rod and connect it to the earth wire in the SWA

 please explain why 

 

This was our setup. Sparky used fairly big core SWA as the run was long (30-40m) and plan was to re-purpose as garage feed, which worked fine until it got damaged when the drive was laid:) One of those moments you're glad there's a run of duct under the very expensive resin driveway that only has a low voltage lighting cable in and just enough room for a new run of 16A SWA.

[ProDave]

1 hour ago, scottishjohn said:

I,m not a sparky , but to me more earthing is good 

so

 

why would you not run 3 core SWA to van and then fit and earthing rod and connect it to the earth wire in the SWA

 please explain why 

Almost all supplies to new properties now are PME, Protective Multiple Earthing, a variation on TNC-S

 

The "earth" comes in combined with the neutral usually on a concentric cable.

 

A know (and not that uncommon) failure is the combined Neutral and Earth (CNE) conductor breaks or corrodes.  In this situation the "earth" in the property can rise well above local earth potential.

 

For this reason, wiring regs prohibit a caravan being connected to a PME earth.

 

On the other hand the SWA must be earthed at source.

 

So in this case you do not connect the SWA at the caravan end and you do not connect in any way to the PME earth. So no need for 3 core SWA.  Instead you provide a local TT earth with an earth rod.

[djcdan]

Having researched SWA cable sizes, my findings, based on our three phase supply, say I should go for:

16mm² three core for house supply - length 12m, 80A (I presume the max Ampage would be 80A since the fuse in the switch fuse is 80A)

1.5mm² three core for treatment plant pump - length 30m, 3.3A
1.5mm² two core for caravan - length 15m, 13A

 

Does this sound correct? Are there any negatives to laying a cable that is too large other than increased cost? 

Also, Screwfix offer a 3/8" and 5/8" earth rod. The 3/8" is what I need?

 

Edited June 3, 2020 by djcdan
text change

[ProDave]

I would fit much larger for the caravan. Mine is wired with 6mm.  13A is not enough what if you want to plug an electric heater in? Unless it has central heating you WILL.

[djcdan]

It does have CH. However, I'll fit a 6mm SWA to be sure, if nothing else. 

 

What size earth rod do you have fitted?

[djcdan]

Quote

 

I would fit much larger for the caravan. Mine is wired with 6mm.

 

All materials have been ordered. I went with the 6mm 2 core SWA for caravan supply, however forgot to order the earth wire to go from caravan CU to earth rod! With a 6mm supply cable, logic would say the earth should also be 6mm. Before I order, can someone confirm that to save the potential hassle down the line. Thanks

[JFDIY]

Buy a roll of 10mm you'll use it on the house build

[ProDave]

Yes use 10mm earth for everything, it's what you need in the house for bonding water, gas etc.