Low wattage panel heaters on dedicated circuit

[Darren Blake]

As part of my girlfriend's CU refurb she's getting her 60A main feed upgraded to 80A, so more current to feed into more toys

As she doesn't have any "easily tun on and offable" central heating (house used to have night storage heaters, now removed) she is thinking of buying up to three 1.2kW oil-filled panel heaters and making a semi-permanent installation out of them. While discussing this with a frend who is also doing up another house it was suggested that these could all be placed on a separate MCB in her nice, new CU.

What I'm wondering is just what would be the best way to have these wired into the CU? While indicidually thermostatically controlled, they will all be on timers, set to come on in the evening and early morning so to all intents and purposes they will all switch on at the same time. Total current draw will be about 16A, which suggests a 20A MCB.

The thing that's not clear is whether to get her sparky to wire these in as a radial circuit or as a ring, and whether the cable size would be different for either? I've had a look at the stuff on tlc-direct and it suggests that a 2.5mm^2 radial circuit with a 20A MCB is fine. The sparky popped in this morning to assess the work required for the CU replacement and we raised this with him and he said that he would reccomend doing it with a full ring using 6mm^ cable.

So on one hand we have a sparky saying do it one way and on the other hand I have a book saying it would be fine to do it another, so I'd appreciate your input.

 

[breezer]

6mm ring

i would run another ring in 2.5, plug in timer for each rad, when more money available hey presto, another ring

 

[Belle427]

or a ring with fused spurs

 

[Darren Blake]

Thanks for the replies

If we go the ring route, the general idea is to make a ring with three junction boxes, one directly above where each of the heaters will be. This will be roughly in the same place as some of the old sto9rage heaters were. The conduit is still in the walls, so the old cable could be pulled out and replaced with new twin & earth, so you would have a ring of junction boxes in the loft (its a bungalow) with spurs coming off each down the wall and a single DP switched socket on the end. Plug in timer in each, and then the heater plugged into that with a 13A fused plug.

The max current each spur would see is just over 5A.

Does this arrangement change anything?

 

[breezer]

yes.

why bother with t & e if you have conduit.

use one or the other, i would suggest the T & E

 

[Darren Blake]

yes.

why bother with t & e if you have conduit.

use one or the other, i would suggest the T & E

Not sure I understand Maybe I'm using the wrong terminology for what's in the walls. I was simply proposing to use the old cable channels to pull through new wires to save having to channel into the walls. Two of the rooms where the heaters will go don't need to be re-decorated, so this would save a lot of hassle.

 

[breezer]

i see.

 

[Spark123]

Something is making me think that on a ring circuit there should be more fsu/sockets on the ring than spurs off the ring, not that it will matter too much.
Are you sure your sparky said 6mm² ring and not radial? Depending on the length of the circuit a 32A radial might be OK.