SWA and earthing

[rob121]

Evening All,
Had the pleasure of terminating 3 swa cables today. Im going to be using this job for my NIC inspection so wanted to double check a couple of things!
First is where ive stripped the cable back, theres about 10mm of steel armouring showing between the gland and the sheathing, obviously this is covered by the black pvc cover. Just making sure this is acceptable?
The 2 cables are both 3 core, ones 4mm and the others 6mm. Im going to use 4mm G/Y tail to connect the gland to the earth terminal. This was based on having page 104 of the OSG where 2.5mm is sufficient for 40A <6ka fault level and having some 4mm laying about? Would I be right in thinking that if the circuit was more than 40 A and the conductor was upto 16mm the the earth would be the same diameter as the neutral?
There was something else but minds gone blank!
Thanks for any input
Rob

 

[Guest123]

As long as the glands are BW glands (indoor type), a small amount of armouring showing behind the back of the gland is normal.

Are you using the SWA as the CPC or is one of the inner cores used???

 

[rob121]

Okay, one of them is an external joint, connecting it to a plastic junction box. Ill look for an exterior gland and swap it.
As regards using the armouring for the cpc, I was going to connect both the armour and conductor. I would of used 2 core cable myself and used the armour for the cpc, but it was already supplied by customer. Is there any issue in using both?

 

[truckster]

No it all helps the earth loop

 

[Guest123]

Okay, one of them is an external joint, connecting it to a plastic junction box. Ill look for an exterior gland and swap it.
As regards using the armouring for the cpc, I was going to connect both the armour and conductor. I would of used 2 core cable myself and used the armour for the cpc, but it was already supplied by customer. Is there any issue in using both?

The gland you need for exterior connections is a CW type. It has an additional nut fitted to the back of the gland body which contains a rubber washer and when compressed forms a seal around the external PVC sheath of the SWA.

 

[rob121]

Thankyou for the replies, I did mention in one of my other posts that the supply cable goes from the house to garage to barn conversion (where were working) to kids play house. Its a TT supply so i plan on adding rods to the garage, barn and playhouse so that it increases the earth potential. Could anyone confirm that I had the right idea about size of cpc? Thanks again for the responses, great forum for people like myself, just starting out!
Rob