SWA cable supplying a shed

[ta-electrical]

Hi, just need to have a question answered;

I am putting in a split board consumer unit in the house and supplying a SWA 6mm cable to an outside shed - supplying a 30mm RCD board which will have a ring main on and a lighting circuit. The SWA cable will be buried all the way through the garden atleast a foot down.

Question : The SWA cable in the house on the main consumer unit should it have a 32amp MCB or a 32amp RCBO - note that it will not be on the main split board itself so, a fault would not trip supply to the shed.

Thanks.

 

[Mark.W]

If you are putting an RCD in the shed I would not stick it an RCBO. Just a thought...if you are putting a new board in why not just stick on the non-rcd side (before the RCD).

You have to have discrimination.

Also only earth the SWA at one end.


Cheers

 

[ta-electrical]

Hi, just need to clarify that last bit.

The SWA cable is 3-core so it has earth in it, will i still need to earth the SWA cable?

If yes, then what exactly do you mean by "only earth the SWA at one end" ?
Would it mean i could earth it on the RCD side in the shed?

I will connect the earth in the SWA to the main earth terminal in consumer unit in the house to provide earth in shed.
So, i will earth the SWA sheath in the RCD in the shed so, it will be earthed at one end.

If there was an earth fault in the SWA cable, will it trip the consumer unit in the house?

Thanks, i appreciate your reply.

 

[Mark.W]

The steel wire should also be earthed mate, you only earth it at one end to avoid introducing parallel paths!

 

[ta-electrical]

I am going to earth the SWA cable at the main consumer unit side in the house. Connecting the SWA cable to the main earthing terminal block and not inside the consumer unit. Is that correct ?

I will be taking a seperate earth in the SWA to the outside shed distribution board and not connecting SWA to anything on this side to avoid parallel paths.

Thanks to all for replies, they are highly appreciated!

 

[Mark.W]

Not sure how you intend on connecting the swa to the earth block, but I would install a metal clad box to connect the swa to then from that run a fly lead to the earth block.