Shipping container.

[barcelona]

flameport wrote:

House to container - 6mm 2 core SWA, armour only connected at house end. Container: SWA into insulated enclosure (or metal one inside a plastic box) so that no part of the metal gland is exposed, and the armour/gland is NOT electrically connected to the container. Consumer unit with 30mA RCD main incomer, MCBs as required. Quote: Earth rod(s) for the main earth connection Bonding from container to earth bar in CU.

Do you mean earth rod to earth bar in cu and bonding from doors and casing to earth bar in cu ?

[RF Lighting]

Yep. The rod provides the main earth, and all the metal work is bonded back to the MET, as with any normal installation.

The only difference is that the container is the extraneous conductive part(s) it this instance, rather than the water and gas supply as normal.

Obviously standard TT regs apply such as DP RCDs etc.

__________________
I downlights

[ban-all-sheds]

barcelona wrote:

My fist thought was 4mm but then thought 2.5 would be adequate.

Absolutely no way.

Please spend some time learning about circuit design and cable sizing before trying to do it in anger.

Here's a good start, but I also recommend getting some good electrical installation textbooks:

http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf

__________________
I mustn't warn people that the "experts" on the plumbing forum can't be trusted to tell the truth.

[flameport]

Aragorn84 wrote:

Why would you not just extend the houses earth outside to the container?

You could, but the container will then need bonding to the main earth terminal in the house, which means at least 10mm cable, possibly larger depending on distance and how it was installed.

[barcelona]

ban-all-sheds wrote:

barcelona wrote: My fist thought was 4mm but then thought 2.5 would be adequate. Absolutely no way. Please spend some time learning about circuit design and cable sizing before trying to do it in anger. Here's a good start, but I also recommend getting some good electrical installation textbooks: Quote: http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf

I did read that article and worked out 2.5 was ok. Obviously I went wrong somewhere.
I also underestimated how much power I might use I think.

Cheers for all the reply's from everyone btw, very helpful.[/quote]

[barcelona]

flameport wrote:

Aragorn84 wrote: Why would you not just extend the houses earth outside to the container? Quote: You could, but the container will then need bonding to the main earth terminal in the house, which means at least 10mm cable, possibly larger depending on distance and how it was installed.

Total distance would be no more than 12m.
If I did it this way I assume I wold not need to use 3 core ?
Should I still use the swa armor as earth ?
How should the main bonding be installed ?
Surely this would be the most ecenomical solution.

Cheers.

[Aragorn84]

If you kept it TN-S and required a 10mm cable for keeping the house earth, how does the CSA of the cable armour compare with 10mm earthing cable?

[barcelona]

Aragorn84 wrote:

If you kept it TN-S and required a 10mm cable for keeping the house earth, how does the CSA of the cable armour compare with 10mm earthing cable?

I mean would I use both or just the 10mm Earth cable.

[barcelona]

If I used 6mm 3 core swa and doubled a core up with the armour would this be ok ?

[ban-all-sheds]

barcelona wrote:

I did read that article and worked out 2.5 was ok. Obviously I went wrong somewhere.

Where does it say that 2.5mm² is OK for 32A?

Aragorn84 wrote:

If you kept it TN-S and required a 10mm cable for keeping the house earth, how does the CSA of the cable armour compare with 10mm earthing cable?

See the tables here:

http://www.diynot.com/wiki/electrics:earthing_supply_types_and_bonding:swa_earthing

__________________
I mustn't warn people that the "experts" on the plumbing forum can't be trusted to tell the truth.

[Aragorn84]

so doesnt that mean the armour on 2 core SWA acts as a 22mm CSA conductor already?

If you wanted more you could always use 3 core and double up the armour and a core as earth?

[barcelona]

ban-all-sheds wrote:

barcelona wrote: I did read that article and worked out 2.5 was ok. Obviously I went wrong somewhere. Quote: Where does it say that 2.5mm² is OK for 32A? I got the calculation wrong. Aragorn84 wrote: If you kept it TN-S and required a 10mm cable for keeping the house earth, how does the CSA of the cable armour compare with 10mm earthing cable? See the tables here: Quote: http://www.diynot.com/wiki/electrics:earthing_supply_types_and_bonding:swa_earthing

I read that.

[Aragorn84]

the other earthing page in the wiki shows the diameters of the earth conductors compared with the supply cables.

which suggests you only need a 10mm^2 earth, i just dont know if the earth is allowed to be provided by the SWA armour.

Might be worth running three core and using an extra core as earth as well just to ensure you've got plenty?

[Spark123]

Aragorn84 wrote:

so doesnt that mean the armour on 2 core SWA acts as a 22mm CSA conductor already? If you wanted more you could always use 3 core and double up the armour and a core as earth?

The armour is a different material hence when using the not smaller than half the CSA of the earthing conductor I'd be inclined to think that to compare them they'd need to be in the same material or apply a correction factor.

[shetland]

Copper equivalents - http://www.earthingnuts.co.uk/pdf/pvc_xlpe.pdf