Power to outside shed, does it need TT earthing

[haptism]

Hi hope someone can help. The shed in the garden is about 15m away from the house. Its supply is spurred from kitchen ring via a 30Ma RCD/13A FCU, the load side of the FCU (2.5mm flex) runs outside and underground (within metal conduit) to an adaptable box where its joined to 2.5mm SWA which runs to the shed. At the shed the SWA is terminated into a 13A FCU, which supplys' 2 sockets and 2 strip lights.


Does this installation require a TT earth system as a matter of course. As it is now the earthing arrangement is via the CPC (including SWA). The house has TN-S system.

Thanks

 

[Deleted member 26818]

From what you have described, no.

 

[Corbs]

Hi hope someone can help. The shed in the garden is about 15m away from the house. Its supply is spurred from kitchen ring via a 30Ma RCD/13A FCU, the load side of the FCU (2.5mm flex) runs outside and underground (within metal conduit) to an adaptable box where its joined to 2.5mm SWA which runs to the shed. At the shed the SWA is terminated into a 13A FCU, which supplys' 2 sockets and 2 strip lights.


Does this installation require a TT earth system as a matter of course. As it is now the earthing arrangement is via the CPC (including SWA). The house has TN-S system.

Thanks

can i ask why didnt you run the swa from the outside point by the fcu to the shed, seems an odd way to run power to your shed ?????????

 

[haptism]

To update, ive found that exporting the TN-S is not looked at favourably; so does the SWA need to be earthed via the TT.

 

[haptism]

can i ask why didnt you run the swa from the outside point by the fcu to the shed, seems an odd way to run power to your shed ?????????

What outside point ?, sorry not sure what you mean

 

[Corbs]

What outside point ?, sorry Im not sure what you mean

where does your swa start on stop eg starts at your house/where the fcu is and ends at the shed?

 

[Deleted member 26818]

Might not be looked at favourably by some.
However not by the Regs or any knowledgeable sparks.

 

[haptism]

where does your swa start on stop eg starts at your house/where the fcu is and ends at the shed?

No the SWA dont start at the house FCU, it starts at an adaptable box under the patio. Dont know why I didn't install it, but i see what you mean

 

[haptism]

Might not be looked at favourably by some.
However not by the Regs or any knowledgeable sparks.

Thats what i thought aswell ! Just checking

 

[Corbs]

No the SWA dont start at the house FCU, it starts at an adaptable box under the patio. Dont know why I didn't install it, but i see what you mean

if it was me i would be looking into getting it change (you might not like that) because unless he has applied some gel and maintenance free connectors, water could get in and corrode / short thing out bad practice if you ask me

 

[haptism]

if it was me i would be looking into getting it change (you might not like that) because unless he has applied some gel and maintenance free connectors, water could get in and corrode / short thing out bad practice if you ask me

Its concreted in

 

[Corbs]

Its concreted in

lol :mad2: if there is a joint under there very bad practice then as access is required

 

[haptism]

lol :mad2: if there is a joint under there very bad practice then as access is required

Yes, all for the sake of an extra meter or 2 of swa.

 

[Deleted member 26818]

Might be that a resin filled joint has been used, or some other type of maintenance free joint?

 

[Corbs]

Might be that a resin filled joint has been used, or some other type of maintenance free joint?

and the only way your going to find out is either phone the spark or start digging unless its on the test sheets

 

[Deleted member 26818]

Just wondering how the OP knows there is an adaptable box under the patio?

 

[davesparks]

To update, ive found that exporting the TN-S is not looked at favourably; so does the SWA need to be earthed via the TT.

I think if you managed to export TNS anyone looking at it would be very impressed! How on earth you can sell an earthing system to another country is beyond me!

However if you were talking about extending an existing TNS earthing system and equipotential zone to include an outbuilding then there is no problem at all so long as you do it properly with respect to the requirements for bonding.
If there are extraneous conductive parts in the shed then there would have to be a main bond of the appropriate size for the intake position (normally 10 mm for a domestic supply)

If you did need to create a TT earth for the shed then the SWA would not be connected to this, it would need to be isolated from the TT earth and connected to the TNS. The bonding and cpcs in the shed would connect back to the MET of the TT system.

 

[ian.settle1]

Just wondering how the OP knows there is an adaptable box under the patio?

Because that is where the house owner put then realised they didn't know what they where doing.

 

[Deleted member 9648]

Cant believe this nonsense still comes up,I suppose TNS makes a minor change from TNCS though.

 

[Prat P]

Its concreted in

you have just found a nice little job as all joints must be accessible so you might as well rip it out and run in armoured cable into the house,or possibly install a weatherproof isolator then you will not need to rip whole of existing cable out. Simply run new armoured cable from supply side of isolator into property.