Some advice about SWA supply to a steel framed barn

Barry E M · 2025-03-19T09:11:08+0000

I'm a 77yr retired sparks whose regs. related memories are a bit cloudy.

On my sons land there is a TN-C-S single phase supply to an existing barn with an 80 amp company fuse

A supply to a second barn is needed using an 3 core swa to be buried. The total load of both barns will be well under 80 amps
Does that swa need rcd protection?
Do I earth both ends of steel armouring?
Cable run is 55 metres absolute max load of 30 Amp
Would 10mm cable be correct?
How best to bond steel barn frame to earth?

westward10 · 2025-03-19T09:40:41+0000

Is this agricultural?

Barry E M · 2025-03-19T12:48:57+0000

Yes various bits of small farming stuff

westward10 · 2025-03-19T13:05:22+0000

Does it involve livestock?

Barry E M · 2025-03-19T16:32:51+0000

westward10 said:
Does it involve livestock?

Yes, for example sheep shearing

westward10 · 2025-03-19T18:59:22+0000

TN-C-S can be employed on an agricultural installation but certain criteria must be met. If you are not conversant with Section 705 of BS7671 then you need to employ someone who is.