Connecting T&E to SWA

[SteWal]

Hi all,

Would appreciate your thoughts on the following.

Customer has a garage CU fed by a 6mm cable from the main CU in the house. The cable exits the house and then is stretched overhead between the house and the garage. The cable is starting to sag and the customer wants it replacing. My initial thought was to replace with swa from house CU to garage CU going underground however, the main CU in the house won’t take swa and gland without pulling it all out and repositioning it, something the customer doesn’t want to do. So I’m thinking of cutting the cable where it exits the house and connecting to swa then dropping down underground and across to the garage. The CU in the garage has 2 radial circuits, 1 socket and 1 light on 32a and 6 a mcb’s respectively. I’m thinking that 6mm cable is way over the top for this demand and looking at 2.5mm swa to connect to the 6mm in a junction box under the roof overhang. The main CU is protected by a 16a mcb. It’s not the ideal solution but I think it’s safe and reasonable - any thoughts?

 

[telectrix]

i.d still use 6mm SWA to allow for any future increase in load. make sure armour is earthed.

 

[ipf]

No way is 6mm over sizing the supply to another CU.
Why are you talking about a 32 amp breaker for a single socket??
Main CU protected by 16Amcb?

 

[SteWal]

No way is 6mm over sizing the supply to another DB.
Why are you talking about a 32 amp breaker for a single socket??

That’s what’s currently in place!

 

[ipf]

That’s what’s currently in place!

RCD involved?

 

[SteWal]

i.d still use 6mm SWA to allow for any future increase in load. make sure armour is earthed.

Thanks telectrix. Yes to earthing the armour although I think I’ve seen on the site somewhere that it’s not strictly necessary if using one of the conductors are cpc. Is this right?

 

[SteWal]

RCD involved?

Yes 30mA

 

[R-fur]

Is there space to put the junction box adjacent to the CU? That way the box is inside and if the CU is replaced in the future the cable could be put into the new CU.

 

[MJPD29]

Thanks telectrix. Yes to earthing the armour although I think I’ve seen on the site somewhere that it’s not strictly necessary if using one of the conductors are cpc. Is this right?

No its not at all. Scary that you would even consider that.

 

[SteWal]

Is there space to put the junction box adjacent to the CU? That way the box is inside and if the CU is replaced in the future the cable could be put into the new CU.

Hi R-fur, no the CU is positioned tight in a corner, looks very neat but difficult to get at plus the cables go outside almost immediately.