long sub main supply

[Stonsey]

Right I don't really do any domestic these days but my parents house requires a new sub main.

My gran owns the house where the supply comes in and parents house is fed in 16mm over heads, on a TT system. One of the poles has rotten and snapped, currently propped up.

My dad wants to trench it and use swa, under my thinking I would use 35mm 2 core swa, protected by 63a bs88 at the supply end, running 90meters under ground and in to parents local isolator for house, I would need to upgrade main bonding to water and oil tank (only incoming services) and upgrade the main CPC to rod. All of this is after the DNO meter.

He spoke to a digger driver to quote for trenching, who is also a sparks and he said you must use 3core swa, I feel no need for the 3rd core due to the TT system.

Looking for advise wether or not I will need to use 3core or not? Cheers

 

[mark80]

2 core SWA is fine if you're going to TT house. Only thing that I'm wondering about is, shouldn't the DNO be replacing all this if the pole is snapped etc???

 

[Stonsey]

Thanks, that was my thinking, it's not DNO equipment, one DNO meter for 2 property's, my dad is generous and pays her bill for her.

 

[micknew]

He does say that the works are after the DNO's meter doesn't he?

 

[telectrix]

if installing TT rod at the load end of the sub-main SWA the 2 core is fine. make sure the armour is earthed and use at least 2 5/8" rods screwed together. go deep.

edit: i would use ducting for the SWA as well, give it that extra protection. don't forget the warning tape above.
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