Bathroom fan heater rcd

[warco]

I am fitting a new IPX4 rated fan heater in my father in laws bathroom.
The consumer unit is an old Wylex fuse type, so I was intending to fit an RCD in its own enclosure adjacent to the CU and feed it from a spare 15 amp fuse.
The fan heater will be cross bonded with 4mm earth cable. Would this pass the councils inspection?
NB Obviously the best thing would be to replace the CU but my father in law who is 88 positively refuses.

 

[Chri5]

I'd suggest running the bathroom circuits (lights and heater) to a small cu / enclosure with either rcd + mcbs or rcbo's and take the feed in from the supply size via a henley block.

There wouldn't be a need for cross bonding, I take it you have 10mm bonding for the water and gas supply back to the MET ?

 

[warco]

I was trying to keep the work down to a minimum so would be utilising a redundant immersion supply.Therefore I didnt realy want to get involved in too much wiring. The bonding is up to date at the supply and uses 10mm cable.

 

[MalcofArabia]

I'm assuming that you are going to use the old immersion cable to feed the heater, or are you running new?

 

[warco]

I do indeed intend to use the old immersion cable as the fan supply. It seems ideal, as it terminates in the airing cupboard just feet from the fan position. So I was going to use a double pole isolater as a junction box and extend out to the fan .

 

[MalcofArabia]

can we also assume that the cupboard is outside the bathfoom seperated by at least a door?

If so are you going to fit the heater in the bathroom drill through a wall and terminate all the cables inside the cupboard outside the bathroom ?

 

[warco]

Yes the airing cupboard is outside the bathroom. I would just need to run the cable for about 1.2 mtrs through the loft, then down through an internal cavity wall (about 300mm) to the heater.

 

[MalcofArabia]

That is a shame as I was going down the path of though the appliance is in the bathroom you may have be able to get away with the argument that as the installation in outside the special location and in an cupboard it may not have to come under the scope of part P................

That would have got a few juices going!!

But as your doing part of the installation inside the bathroom then you definitely going to have to certify it.

The only trouble is that the existing cable will most likely have to extended from the existing CU to your new box, to be terminated into the load side of your RCD. Then run a new cable from the 15amp rewirable to the load side of the RCD ........all notifiable work I'm afraid

Then you are going to have to test it all to make sure you haven't affected the disconnect times. Though the RCD will trip before the fuse Zs for the new cable to the new RCD box will have to be done and then you have to do one from the heater to the RCD as you will have 2 different protection devices ..........so do you think you can do all that

 

[warco]

Should be no problem. It`s only a matter of measuring the resistance of the primary supply and load supply cables. I have a resistance meter that conforms to 16th edition regs. eg 200ma pass current.

 

[kai]

If the rating of the bathroom fan heater is 2kW (mine is), a B10 breaker (or 10A cartridge fuse in the fused spur) will do fine for that load (2000w divided into 230 volts gives you just under nine amps for the design current).