- Reaction score
- 74
Please could someone enlighten me on how grouping factors apply to ring final circuits run together, e.g. sharing holes through joists and walls, in a domestic situation?
For one RFC run in 2.5mm T&E under first floor boards (ref method B) the cable rating is 23A.
If you group two RFCs together, i.e. four 2.5mm T&E cables, then I think this counts as two circuits giving a grouping factor of 0.80 and therefore a cable rating of 18.4A, which is less than the allowed minimum of 20A for each leg of the ring.
This seems to suggest to me that you can't group a 32A 2.5mm T&E RFC with any other circuit?
What I really want to get to the bottom of is: is it ok to run two 32A 2.5mm T&E RFCs together, though the same joist holes, and if so how can this be justified?
Thanks
For one RFC run in 2.5mm T&E under first floor boards (ref method B) the cable rating is 23A.
If you group two RFCs together, i.e. four 2.5mm T&E cables, then I think this counts as two circuits giving a grouping factor of 0.80 and therefore a cable rating of 18.4A, which is less than the allowed minimum of 20A for each leg of the ring.
This seems to suggest to me that you can't group a 32A 2.5mm T&E RFC with any other circuit?
What I really want to get to the bottom of is: is it ok to run two 32A 2.5mm T&E RFCs together, though the same joist holes, and if so how can this be justified?
Thanks