Radial circuit question

[John]

I'm rewiring the house and whilst most socket outlets will be on the RCD side of the split load CU, there are one or two things I don't want protected by the RCD so I intend making use of a radial circuit for these.

I've used a 20A MCB and I've run 2.5mm T&E to a single socket on one kitchen wall for the fridge, then over to the opposite wall for a single socket for the freezer. I've then taken it up into the loft to an FCU (fused at 3A) feeding the boiler and a single socket feeding a TV distribution amplifier - a total run of approximately 17 metres.

My question is, can I extend it a further 3 meters to drop down into the bathroom and feed a fan heater, such as this one:

2kW, that would be the highest rated load and it would be right at the end of the cable run so would this be OK?

Cheers,

John.

[Owain]

It should be OK, but why would not want the bathroom heater to be non-RCD protected?

Owain

[Fash]

Should be fine. Max length for a 20A MCB fed radial in 2.5mm is 33m. This assumes there is no derating due to running through insulation or bunching with other cable. As a socket circuit it is assumed that you might plug anything in at any point so the standard circuit should cover for this. I got the length from another web-forum (careful searching) but will check in the OSG tonight. It will be somewhere in Table 7.1 (I think that's the one).

Alternatively someone who has learnt the OSG by rote may be able to confirm quicker than this.

Fash

[Fash]

Forgot to add there is also the caveat about only supplying a 20sqm area in total. You should be OK on this. You may want to check that you aren't likely to end up pulling more than the rated 20A if everything is going though.

Fash

[John]

It's not a concious decision that I *don't want* it protected by the RCD. It's just that the bathroom is fully tiled which rules out chasing a cable up the wall from the upstairs ring main. The fan heater will be wall mounted, quite high up, and so it's easier to drop a feed down from the loft where a power feed already exists.

John.

[John]

Thanks Fash, all noted.

John.

[Owain]

Ah, right.

If the heater will be touchable (whether within the zone or not) I'd then suggest using an RCD FCU for connection.

Of course, to comply with Part P you'd have to run it off an extension lead under the door anyway...

Owain

[John]

Good points Owain, thanks.