Checking installation methods of RFC

[hightower]

Hi all,

Been asked to installed some sockets in our sports hall. These are to power 4x 3kW blow heaters (yes, I know little blow heaters aren't the most efficient method of heating a large room like this, I've made my arguments and may be given the budget to do a proper IR heater install in future, but this is just a short term fix for now).

Anyhow, I was originally thinking 4x 16A radials would be best, each supplying a single socket. Then I thought perhaps 2x 32A RFCs would be more adaptable in the future if I need to pull more sockets off for another purpose.

My plan is steel conduit, singles, 32A type B RCBO, each RFC feeding 2 sockets. The furthest socket will be around 20-25m away from the board.

I'm just undecided - 2x RFCs, or 4x radials. What do people think?

 

[Pete999]

Hi all,

Been asked to installed some sockets in our sports hall. These are to power 4x 3kW blow heaters (yes, I know little blow heaters aren't the most efficient method of heating a large room like this, I've made my arguments and may be given the budget to do a proper IR heater install in future, but this is just a short term fix for now).

Anyhow, I was originally thinking 4x 16A radials would be best, each supplying a single socket. Then I thought perhaps 2x 32A RFCs would be more adaptable in the future if I need to pull more sockets off for another purpose.

My plan is steel conduit, singles, 32A type B RCBO, each RFC feeding 2 sockets. The furthest socket will be around 20-25m away from the board.

I'm just undecided - 2x RFCs, or 4x radials. What do people think?

HT 4 Radials Mate.

 

[SparkyChick]

I might be inclined to install them as 16A radials powering a single socket. Run two circuits in one conduit and include an extra set of singles between the two sockets so you can convert to a ring if needed at a later stage without the hassle of pulling in new cables.

 

[hightower]

I might be inclined to install them as 16A radials powering a single socket. Run two circuits in one conduit and include an extra set of singles between the two sockets so you can convert to a ring if needed at a later stage without the hassle of pulling in new cables.

Those cables would then need tying to earth somehow though. But I like your thinking. 4x 16A radials it is. I liked the convenience of a ring but one of first things I saw when looking in Appendix 15 was 'not supplying comprehensive space heating', so RFC out then.

Cable calcs say 2.5mm cable is alright, table in OSG says 40m max run (which is fine), space in the board for the 4 RCBOs, conduit will gladly take 6x 2.5mm cables. We may have a winner.

 

[SparkyChick]

Earthing... no problem... slim-line 5 way Wago at one end of the spares tied into the earthing

 

[telectrix]

should you not link to E at both ends, saves having ends flapping about.

 

[SparkyChick]

should you not link to E at both ends, saves having ends flapping about.

Bit of tape, fold them over into a loop and stuff the ends back up the pipe?

 

[SparkyChick]

I'm being a bit flippant because it's more interesting than what I have to do this morning... remove some existing RFC cabling and replace it, hopefully finding a chunk taken out of the cable that would explain the crappy IR readings on the two cable segments I'm replacing.

 

[hightower]

I'm loving my workload at the minute, it's got me thinking about all the stuff I've learned about over the years. Beats doing a typical house rewire where the boss says "just drop a 10mm in for the shower".

Now I'm thinking do I drop 4mm in or am I happy with 2.5mm. The calcs all check out for 2.5mm but I'm just thinking if I need to extend in the future for some reason.

 

[Toneyz]

I'm loving my workload at the minute, it's got me thinking about all the stuff I've learned about over the years. Beats doing a typical house rewire where the boss says "just drop a 10mm in for the shower".

Now I'm thinking do I drop 4mm in or am I happy with 2.5mm. The calcs all check out for 2.5mm but I'm just thinking if I need to extend in the future for some reason.

Don't overthink it, it is 4 radials for 4 heaters unless you are thinking of what the correct way of heating the hall is (maybe in the future).What was your calculation for heating the hall correctly also how is the temperature being controlled eg roomstat.

 

[hightower]

I haven't done any calculations for heating the hall yet, that'll come when someone says "aye, stick some proper heating in"

 

[Toneyz]

Is there not some form of existing heating or has it had its day?

 

[Deleted member 72666]

I'm assuming you're not going to use BS1363 sockets to supply these heaters because if you are you'll be back time and time again replacing the charred plugs and sockets. 16a 2p+e to BS4343 would be my choice if not using fcu's.

 

[telectrix]

or a 20A D/P switch (neon optional).assuming that the flex to the haters is rated to 16A or above).

 

[hightower]

Don't want the heaters hard wired due to it being a sports hall. I'm sure I'll get funding to do the job properly with suspended IR heaters eventually, but yes, this is a short-term fix and although not ideal it will help us to get through 3 weeks of exams starting Monday.