Exporting PME to wooden shed

[Livehornet]

I wish to run a 10mm 2 core swa to the above approx 33m from house. Existing house ccu has no provision for RCD protection or spare ways so it's a tails split job.

Intention is to use armouring as cpc and bond it at house end only. My question is as there appears to be no extraneous conductive parts in the shed, does it require TT'ing?

 

[EFLImpudence]

Intention is to use armouring as cpc and bond earth it at house end only. My question is as there appears to be no extraneous conductive parts in the shed, does it require TT'ing?

Appears to be isn't good enough.

If you can bond any extraneous-c-ps should they appear with equivalent to 10mm² copper then TTing isn't necessary.
TTing is usually done to save having to have a 10mm² copper conductor back to the house.

Is 3 core that much more of a cost to cover any eventuality?

 

[EFLImpudence]

The armour on 10mm² 2 core looks ok but some people will tell you they don't like it because it corrodes.

Obviously if there are no e-c-ps then it doesn't matter.

 

[EFLImpudence]

The work is legally notifiable to the Local Authority.

 

[JohnW2]

The armour on 10mm² 2 core looks ok but some people will tell you they don't like it because it corrodes.... Obviously if there are no e-c-ps then it doesn't matter.

If it corroded to the extent of losing continuity, the lack of a CPC in the supply to the shed presumably would 'matter'!

Kind Regards, John

 

[Livehornet]

Your right, 'appears to be' belongs in the same category as 'assumes' (aka 'an ass of u and me').

I was taught never assume but I'm still learning go easy on me


Fwiw, I'll prolly go with 3 core then and not connect it at TT end. There is no extraneous parts I should have made that clearer.

The swa at house end will be in it's own enclosure with a 100ma type s RCD. Thinking of which, is that necessary?

 

[Livehornet]

Yes I know this work is notifiable to labc.

 

[JohnW2]

The swa at house end will be in it's own enclosure with a 100ma type s RCD. Thinking of which, is that necessary?

An RCD is necessary but, since you are feeding the shed via SWA, the RCD does not have to be at the house end (unless there is buried non-SWA cable in the house before it gets to the SWA) . You could have just a 'switch fuse' at the house end and have the RCD in the shed (probably in a mini-Consumer Unit) if you wanted.

Kind Regards, John

 

[EFLImpudence]

The swa at house end will be in it's own enclosure with a 100ma type s RCD. Thinking of which, is that necessary?

No, undesirable.

That's the point of using swa - so an up front RCD is not required.
Put RCDs in the shed on each circuit.

Didn't see John's reply.

 

[EFLImpudence]

If it corroded to the extent of losing continuity, the lack of a CPC in the supply to the shed presumably would 'matter'!

I meant the csa doesn't matter.

 

[JohnW2]

No, undesirable. That's the point of using swa - so an up front RCD is not required.

In the OP's situation, in that the RCD at the house end would be a 'dedicated' one, it is much less 'undesirable' than if it is fed from a house CU (sharing an RCD with other house circuits). The only real downside I can think of is the slight inconvenience of having to go to the house to reset the RCD if something in the shed trips it - which is why I said that it was essentially the OP's choice as to 'which end' he had the RCD.

Put RCDs in the shed on each circuit.

Did you mean RCBOs, rather than multiple RCDs?

Kind Regards, John

 

[JohnW2]

I meant the csa doesn't matter.

Oh, fair enough. And you will realise, that's not how I read it.

Kind Regards, John

 

[EFLImpudence]

The only real downside I can think of is the slight inconvenience of having to go to the house to reset the RCD if something in the shed trips it - which is why I said that it was essentially the OP's choice as to 'which end' he had the RCD.

...and, of course, all circuits being disconnected with a fault on one.

Did you mean RCBOs, rather than multiple RCDs?

RCBOs are RCDs.

 

[Notch7]

What would happen if the swa at house end has a consumer unit with RCD and at other end garage type consumer unit with RCD.

Would it not be natural to start at mcb in house consumer unit -which may well be RCD (I realise swa may be terminated in metal box before cu).

If using one of the copper cores as an earth, is the swa steel armour connected to earth at both ends as well as the copper core?

 

[JohnW2]

Would it not be natural to start at mcb in house consumer unit -which may well be RCD (I realise swa may be terminated in metal box before cu).

That's the approach which is 'undesirable' (albeit very common) - since in the event of a fault in the shed, it would be pot luck as to which (or both) RCDs would trip, and if it were the house one that tripped, it would take out a number of house circuits as well as the shed one.

If using one of the copper cores as an earth, is the swa steel armour connected to earth at both ends as well as the copper core?

Certainly at the house end but, sensibly, at both ends, since it then would considerably enhances the CPC/bonding connection to the shed.

Kind Regards, John