Ring Circuits - Fixed Electric Heating

BS 7671 isn't particularly prescriptive about circuit layouts. Regulation 433.1.204 describes one common ring circuit arrangement (supplying BS 1363 accessories, which includes fused connection units as well as socket outlets) - but that is more of a  'do this and it is deemed to comply' to avoid the need for calculation in the common case. There's nothing to prohibit other arrangements at all, but a little more design effort is likely to be needed to show compliance with the basic requirements of BS 7671 (especially with regards to overload protection of the ring cables).

The arrangement you describe doesn't sound too far from the usual arranagement, but perhaps some care is needed to show that 'the circuit is unlikely for long periods to exceed the current carrying capacity of the cable'. The choice of 4mm² cable rather than the usual 2.5mm² may well provide reassurance on that score, but a lot depends on the installation method - it could have an ratiing of below 20A if installed within an insulating wall for example. Likewise the position of loads around the ring will affect how well the current divides between the two legs.

BTW 6kW feels like an awful lot of heat for a living room - many whole houses can be kept warm for a lot less than that.

     - Andy.

BS 7671 isn't particularly prescriptive about circuit layouts. Regulation 433.1.204 describes one common ring circuit arrangement (supplying BS 1363 accessories, which includes fused connection units as well as socket outlets) - but that is more of a  'do this and it is deemed to comply' to avoid the need for calculation in the common case. There's nothing to prohibit other arrangements at all, but a little more design effort is likely to be needed to show compliance with the basic requirements of BS 7671 (especially with regards to overload protection of the ring cables).

The arrangement you describe doesn't sound too far from the usual arranagement, but perhaps some care is needed to show that 'the circuit is unlikely for long periods to exceed the current carrying capacity of the cable'. The choice of 4mm² cable rather than the usual 2.5mm² may well provide reassurance on that score, but a lot depends on the installation method - it could have an ratiing of below 20A if installed within an insulating wall for example. Likewise the position of loads around the ring will affect how well the current divides between the two legs.

BTW 6kW feels like an awful lot of heat for a living room - many whole houses can be kept warm for a lot less than that.

     - Andy.