Ring final extension

[SparkyTris]

Which is correct topology - A or B? (JBs are 3pole, all other factors such as current ratings, diversity, derating etc not in question)

Untitled

• SparkyTris
• 2 Sep 2013
• 1

 

[leeco]

I would say B as its a ring all the way round.

 

[plugwash]

B is a conventional ring topology.

A has a couple of issues, the first is it's difficult to test properly (especially if the person testing doesn't know if it's there) meaning a broken ring may go unnoticed. The second is it increases the chance of one or both of the rings becoming badly unbalanced. I'm not sure if it's explicitly forbidden or not but it's certainly considered unconventional and bad practice.

 

[flameport]

A is wrong.
B is correct if you want it as a ring.

Option C is a better choice, which involves changing the ring into 2 separate 20A radial circuits.

 

[PrenticeBoyofDerry]

B is correct but the junction boxes would need to be accessible.
I would try to extend without the use of JBs if possible, or use MF boxes.

 

[bernardgreen]

I would try to extend without the use of JBs if possible, or use MF boxes.

Or use sockets instead of junction boxes, you can never have too many sockets.