Supply to OUTBUILDINGS

[pushrod]

whats the best way of doing this as its really classed as a spur ?

i was going to put a new CU in the shed with 6 and 16A MCB for lights and sockets with a another one in the utility room with the 20A, however the regs state that a fused spur must be limited to a rating of 13A

i was also not going to fit a RCD as per the RCD in series i keep reading about

run it to a 13A metal clad FCU in the shed and wire it in either1.5mm T&E clipped direct, or 1.5mm singles in plastic conduit. Can't really see the point in a submain, just alot of expense.

 

[sirocco]

Waye,
Again, great post
Would the layout shown the diagram hold good for a TN-S system as well as PME?
Graham

Hi again,

I don't think many people have got a copy of 'Guidance Note 8', so I though I'd post this scanned picture from it.

Quite informative, I thought.

The sizes given are much higher than you'd see in a domestic - but the principal is the same, just scale it down.

It shows the two options for additional buildings using a TN-C-S supply. Building B3 is using the existing earth system and Building B2 is using a rod.

You'll notice that the combined CPC and Protective Bonding Conductor running to building B3 is 35mm, as are the bonding conductors in B3, even though the Line and Neutral conductors feeding B3 are only 25mm - this is because their selection is based on the supply neutral (120mm), and not the neutral feeding B3 itself (25mm).
This wouldn't matter to a domestic, as the size of protective bonding conductor remains at 10mm for a supply neutral up to 35mm

The regs quoted are the 16th reg numbers, as the IEE haven't thought it necessary to update GN8 to the 17th yet - I think a lot of the info didn't change.

This was the 2nd best £25.00 I've ever spent, by the way, so if anyone is thinking of buying it - go right ahead.

I'll probably post some more info from it when I get a minute Hope it helps.

 

[jase]

Waye,
Again, great post
Would the layout shown the diagram hold good for a TN-S system as well as PME?
Graham

what about if the main house was a TT?

 

[burt]

A definitive answer to this question (without it being immediately corrected) would be really nice. Do we rod the outbuilding and separate the earthing system from the house when supplying an outbuilding?

 

[telectrix]

A definitive answer to this question (without it being immediately corrected) would be really nice. Do we rod the outbuilding and separate the earthing system from the house when supplying an outbuilding?

read post#2 and others that explain it clearly.

 

[Deleted member 9648]

A definitive answer to this question (without it being immediately corrected) would be really nice. Do we rod the outbuilding and separate the earthing system from the house when supplying an outbuilding?

Definately maybe or not at all.

 

[Joe V.]

Although I think Pushrod may misunderstand the definition of 'extraneuos' (I also misunderstood the exact definition before someone on this forum corrected me), I agree with him on his point about earthing pipework. If I saw a house with a copper heating system, which had been electrically dissconected from the boiler by a short section of plastic pipe, I would want the remaining copper pipework to be bonded.
There are far too many ways a pipe (and all the radiators and taps connected to it)could become live. I should think that there are enough sparks who have seen live unearthed metalwork to agree

It may not be covered by the regs, but it's good practice at the very least.

This reminds me of a house where the CH radiators/pipework repeatedly attracted lighting strikes through the wall (breeze block & timber frame). Does / how does the presence of a lightning protection system on the outbuilding influence the choice of local rod or extending Earth from the main building ?

 

[GMES]

The thread is 3 years old so time to close it.