spur from ring main

[thirdtimelucky]

I have a spur from the ring main, terminated in the loft in a fcu. The fcu supplies a load (approx 600 watts) to a shower booster via a pull switch in the bathroom (C U protected by rcd).
I want to fit a bathroom wall fan heater (1kw). Can I install a j/b in the loft and branch off a cable to a second switched fcu outside of the bathroom and cabled to the wall heater.
I estimate that total wattage to be about 1500 watts with a 3 amp fuse for the power booster and a 10 amp fuse for the wall heater.
Would this cable arrangemment satisfy current regs?

 

[EFLImpudence]

No. The other way round.

Fit a 13A fuse in the existing FCU and connect the new heater cable to it along with booster cable.
Then fit another FCU with a 3A fuse in the cable to the booster.

 

[thirdtimelucky]

Thanks. So the first FCU will have one supply and 2 load cables from it with one of them being dropped down to 3 amp via a second FCU?
Would it be ok if these FCU's were in the loft? I thought at least the fan heater FCU would need to be ouside of the bathroom wall and visible?

 

[EFLImpudence]

Thanks. So the first FCU will have one supply and 2 load cables from it with one of them being dropped down to 3 amp via a second FCU?

That's right.

Would it be ok if these FCU's were in the loft? I thought at least the fan heater FCU would need to be ouside of the bathroom wall and visible?

Yes. It may be inconvenient but that is up to you.

Not necessarily outside the bathroom, just more than 600mm. in a vertical line from the edge of the bath or shower.

 

[ericmark]

I do remember the regulation about the isolator being within view of the operator, but there was a proviso that the motor needed to be over a set size, and neither of your motors is big enough to worry about, 0.37 kW was the limit.

 

[winston1]

You don't need the second FCU. The pump and heater can share the one at 13 amps. The fuse is to protect the cable not the pump or heater.

Using a 3 amp fuse on a 600 watt motor is stupid anyway. The switch on surge is likely to cause it to nuisance fail.

 

[ban-all-sheds]

Then fit another FCU with a 3A fuse in the cable to the booster.

Or not.

That FCU is not needed, so why install it?

 

[EFLImpudence]

So that he'll have separate switches for shower and heater?

 

[EFLImpudence]

In case he has used 3A cable and isn't sure if applying 433 would be appropriate?

 

[winston1]

So that he'll have separate switches for shower and heater?

No doubt the shower and heater have switches on them. I doubt that he will go into the loft every time he uses the shower or heater to switch them on and again afterwards to switch them off.

 

[winston1]

In case he has used 3A cable and isn't sure if applying 433 would be appropriate?

And where would he have got 3 amp cable from? Even 1.0 mm twin and earth is good up to 16 amp.

 

[ban-all-sheds]

So that he'll have separate switches for shower and heater?

In case he has used 3A cable and isn't sure if applying 433 would be appropriate?

You'll be needing this soon:

 

[EFLImpudence]

Absence of humour springs to mind.
Obviously neither of you spotted the (deliberate) mistake in my responses.

Didn't someone recently say something like "Because it's not required does not mean it's prohibited"?

I feel it was and is the best advice to a DIYer in the circumstances with the information we have.

It could be argued that neither FCU is required but what responses would that have attracted.


Are we, in future when asked a relatively simple question, to advise the questioner of ALL of the options available regarding cable size and fusing, omission of overload protection, fault protection, and quote the relevant regulation so that they may defend it when questioned?

 

[EFLImpudence]

No doubt the shower and heater have switches on them. I doubt that he will go into the loft every time he uses the shower or heater to switch them on and again afterwards to switch them off.

I don't think functional switching is their purpose.

And where would he have got 3 amp cable from? Even 1.0 mm twin and earth is good up to 16 amp.

Does that make sense?

 

[ban-all-sheds]

So that he'll have separate switches for shower and heater?

He'll have one switch which does the shower, and one which does both.

In case he has used 3A cable and isn't sure if applying 433 would be appropriate?

Is it likely that "3A" cable would have been used?

Are we, in future when asked a relatively simple question, to advise the questioner of ALL of the options available regarding cable size and fusing, omission of overload protection, fault protection, and quote the relevant regulation so that they may defend it when questioned?

Why not? That people should learn, and come to genuinely understand what they are doing, is the way it should be.