TNS Supply in Garage then T&E to House!

[partypest]

This is the current set-up.

There's a TNS incoming to a detached garage, this is split from an old MEM fused isolator (the tails go straight in) and has a send to the CU via some 10mm T&E going under ground and up into the house. There's another feed from the fused isolator to another, smaller, fused MEM box for the garage supply.

The service head's in a right state, there was a bit of red tape round one of the fuses holding most of the plastic together. The DNO are sorting this today and putting a new bond on to their armour so I can improve the earth, but this is a right headache to get up to 17th.

So far as I can make out, I'm going to need to create a MET in the garage, put a distribution board in the garage, and have a SWA (with the armour bonded to the MET) distribution circuit put under the ground to the house, and then a new CU with the armour from the SWA as the main earth in to the house and create another MET for the gas and water bonding.

I'm not looking to get into the CSA's here, that's just maths, but does the principle meet 7671?

Anybody see any problems with this?

 

[Jonny66]

"Anybody see any problems with this?" - Yes, a few............... Just wondering how one would "create" an MET, I would normally just buy one and install it..one being the optimum number and two being too many.......I've lost interest sorry

 

[Engineer54]

Whilst the SWA cables armouring is going to be fine for the sub-mains CPC, it's not going to be suitable for bonding requirements, between the MET at the origin and the EMT at the CU. So you will need either a 3 core SWA or a separate 16mm earth conductor for the situation you describe....

 

[partypest]

Thanks Jonny66, very helpful.

 

[partypest]

Thanks Engineer54. I think the separate 16mm conductor sounds better than using the armour for bonding AND sub-mains CPC but it'll have to run underground so 3 core SWA it is. It's a weird set-up, almost like the builder wasn't sure where he was putting the house!