Checking installation methods of RFC

[hightower]

Why would there be 2x4mm @Adam W ? I'm running dedicated radials, 16A breaker, single socket (for a single 13A appliance), 1x2.5mm.

As for the FCU question, I'd have thought it would have been obvious from the information I've posted already. This is a sports hall. Having blow heaters lying around the floor when little Johnny is playing footy isn't going to be very useful. On plugs, they can plug them in when the room is due to be used for exams, unplug them when due to be used for sports.

 

[hightower]

Maybe, but 3000/240 = 12.5, 240v being more like what you actually get in the UK. 2x2.5mm are easier to terminate than 2x4mm. If the ring only consisted of FCUs supplying heaters then that would make it a "dedicated circuit" would it not?

Hmmm good point, thanks. Remind me, what reg is it that says we're allowed to design by 240v again? I forget.

 

[Pete999]

Nice

Hmmm good point, thanks. Remind me, what reg is it that says we're allowed to design by 240v again? I forget.

HT nice

 

[Adam W]

I thought you were asking for suggestions.

 

[ipf]

Think of the amount of callouts if you fitted these heaters on a 13 A fcu
3000W /230 =13.04A mps wouldn't take long to blow those would it, an why Ring Final, what's the point? plus the BS 7671 RECOMENDS that a fixed load of plus 2KW would be better on a dedicated circuit.

They would take a bit of 'blowing' but, from what I've seen, the plug/sockets would be giving a fair bit of heat off.
One place has one on a 4mm radial (a couple of other sockets involved) no fuse problems but a lot of heat at the plug....it worries them a bit.
What surprises me about these 3kw heaters is that some do come with a 13amp plug top fitted.
If you're looking to future additions, maybe 4mm2, DP switches.

 

[ipf]

They would take a bit of 'blowing' but, from what I've seen, the plug/sockets would be giving a fair bit of heat off.
One place has one on a 4mm radial (a couple of other sockets involved) no fuse problems but a lot of heat at the plug....it worries them a bit.
What surprises me about these 3kw heaters is that some do come with a 13amp plug top fitted.
If you're looking to future additions, maybe 4mm2, 20amp DP switches.

 

[Adam W]

Nice

HT nice

Perhaps you'd care to explain that one then Pete?
How is asking for suggestions and then making sarcastic jabs when people do suggest things "nice"?

 

[hightower]

I thought you were asking for suggestions.

I am mate, but I would prefer it if the suggestions complied with the rule book.

 

[Risteard]

A ring final circuit serving two single socket outlets seems daft to me.

 

[Flanders]

As others have said i would go for 16 amp sockets id go for the gwis switched interlock ones as they can take a good bashing from them pesky kids

 

[Adam W]

A ring final circuit serving two single socket outlets seems daft to me.

I'm not too sure what OP means by "blow heaters" - I took that to mean some kind of fan heater; turns out he wants to put free-standing heaters on the floor which can be cleared away so they don't get knocked over. I would have been more inclined to use 3x 2400W (probably infra red) heaters at high(ish) level per ring, x2. I've done this before and nothing burned out since the heaters were designed to work through a 13A fuse.
It seems he's intent on going for individual 16A radials wired in conduit as a temporary measure for 3 weeks at a time when heating may not even be required at all.

If any alterations are going to be made to this setup it's likely to be that the commando sockets are changed for BS1363 to make them more flexible, eg so the cleaner can plug in a floor polisher or vacuum cleaner, whereas hard-wiring everything permanently makes it more of a 'dedicated circuit'.

The whole thing seems daft to me.

 

[Adam W]

I am mate, but I would prefer it if the suggestions complied with the rule book.

Meaning what exactly? Where does BS7671 give a value of nominal voltage as 230V, or for that matter any figure other than low voltage "Exceeding extra low voltage but not exceeding 1000Vac or 1500Vdc between conductors, or 600Vac or 900Vdc between conductors and earth"?
Have you actually measured the voltage in this sports hall of yours or are you just going to guess?

 

[Ian1981]

It’s very difficult to design a circuit to a voltage that can vary so using 230 v and designing to this voltage for calculating loads and volt drop gives us a good safety margin to design too I find.
That said some manufacturers put 240 v on the information plates so in that case I use that.

 

[Toneyz]

See appendix 2 from 1995 230v is the nominal voltage that tables and calculations are worked out from.