lighting in the metal shed

[mike larry]

Hi,

Need a word of advice, how should I run supply to two metal sheds that are located about 20m away from the main DB. Should I run in SWA with 10mm bonding and as separate circuit to each shed or through sub-board adjacent to them? What IPX of switch and lighting should be, I'm expecting some condensation as the sheds seems sealed?
Thanks
Mike

 

[Zdb]

What earthing arrangement do you have?

 

[mike larry]

Hi, there is TNCS

 

[Octopus]

Ask your scheme technical line?

 

[123]

Ask your scheme technical line?

Do you contact yours all the time then?

 

[Octopus]

Do you contact yours all the time then?

Its been a while, but I tend do the same sort of work most of the time ......

 

[ChrisElectrical88]

What size SWA are you running for the supplies, whats the load on each?

Will need to add a TT system as you cant export the PME

Edited

 

[driverman]

I believe you can have the SWA connected to the home earthing arrangements, in this case TNCS. At the shed consumer unit when terminating the SWA use a plastic compression gland only. This will then separate the SWA earthing from the shed earthing arrangements. As the shed is of metal construction TT earthing will be required.

 

[mike larry]

I'm thinking of sub-DB that split into two 6A lighting circuits, 4mm2 cable. Earthing arangement is TNCS so ideally 10mm bond but have no experience with this, so I can TT with RCD protection.

 

[ChrisElectrical88]

If 4mm is your calculated cable, run this as a normal circuit from your internal dist board. However when terminated into you new dist board you will need to seperate the earth and all paths back to the PME system. Then install a earth rod and TT the new installation. Dont forget to use the correct RCD protection for tmyour circuits, and if neccessary bond the metallic sheds.