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Topic Title: TT or PME?
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Created On: 02 October 2017 07:54 PM
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 02 October 2017 07:54 PM
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yellowvanman

Posts: 26
Joined: 06 August 2016

Supplying large remote wooden building, comprises dog kennel, office, store room, car port, and workshop. Sockets and lights in all parts (except kennel).

All build on concrete base, no extraneous parts in wooden building. House is a farmhouse with PME. One overhead pole between transformer (tfmr is about 40m away) to house is less than 10m away from wooden building and has an earth on it.

Export PME or TT building supply? I'm thinking TT, but exporting PME would be easier!
 02 October 2017 09:45 PM
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leckie

Posts: 4320
Joined: 21 November 2008

Well it wouldn't bother me to export a pme in such a situation.
 02 October 2017 11:05 PM
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UKPN

Posts: 659
Joined: 17 January 2012

Remote building, concrete base, canopy, animals, wooden construction. It all points to an independent earth electrode and RCCD.

Regards, UKPN.
 03 October 2017 12:01 AM
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mapj1

Posts: 9349
Joined: 22 July 2004

Well, you could probably do either - will the garage ever house an electric car charging point, and is there a risk of caravans being plugged in ?
I presume the kennel is small dogs, but if larger animals like horses or cows are nearby, then these are less happy should there ever be a CPC to terra-firma offset voltage. If you look at the draft of the 18th edition, which I think has now dropped off the BSI website, it will soon require an earth rod on the PME supply anyway, or a connection to the steel rebar in the concrete slab, which is dead easy to do, but presumably rather too late now it is poured.
If you think it is an agricultural setting I'd expect (705.411, and a bit later on the section specifically about fire) an RCD or two at or near the incoming supply, so the only installation difference between TT and PME is the link between the armour of the supply cable and the local earth.
So, is it mostly like a house, with a little bit of kennels, or more like a farm, with a small office attached?

-------------------------
regards Mike
 03 October 2017 06:23 AM
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leckie

Posts: 4320
Joined: 21 November 2008

From the description it sounds like a general use building, with a space for a dog kennel. So I presume that is not commercial kennels. As Mike says, that's a bit of an assessment / judgement call and partly based on information from your client. If it is not considered to be a building for holding livestock I would think you are more in the realms of a large shed. If that's the case then exporting the PME should be fine, like nearly every detached building in the UK, and would normally comply with the regulations. If you want a belt and braces, all angles covered solution, then TT is the way to go.
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