Bathroom electrics

[Tester]

I am undergoing the installation of a new bathroom. The bathroom currently has a single light operated by a pull cord and an electric shower on its own 40A circuit isolated by a pull cord in the bathroom.

I intend to install additional lighting operated by a dimmer switch outside the bathroom.
An electric fan operated by a switch outside the bathroom.
An electric light over the sink.
A shaver socket with a transformer near the sink.
A whirlpool bath.
Electric underfloor heating.

Additional electric lighting - I intend to extend the lighting and run a wire down to switch outside bathroom. I am comfortable with this piece of work.

Electric Fan - I understand this requires wiring to a fused spur from the power ring protected by a 3A fuse.

Electric light over sink - I understand this can be a spur from the lighting circuit

Shaver socket - I understand this can be an earthed spur from the lighting circuit.

Whirlpool bath - I understand this should be connected to a switched, fused spur from the power ring with a rccb (the house is protected by an RCB at the consumer unit - do I still need a RCB to the bath?).

Underfloor heating - I understand this should be connected to a switched, fused spur from the power ring.

This set up would require 3 fused spurs from the power ring - can these all be taken from the same point or must each fused spur be taken from a different point on the ring?

 

[Big_Spark]

Electric Fan - I understand this requires wiring to a fused spur from the power ring protected by a 3A fuse.

This can be run from the lighting circuit, but must include a local 3 pole Fan Isolator switch adjacent or reasonably near to the fan unit. You do not need to run this from the ring via a spur.

Electric light over sink - I understand this can be a spur from the lighting circuit

Shaver socket - I understand this can be an earthed spur from the lighting circuit.

You can buy combined units, and again this can be run from the lighting circuit, usually these incorporate a small pullcord or other type of switch for the light, but they can be remotely switched.

Whirlpool bath - I understand this should be connected to a switched, fused spur from the power ring with a rccb (the house is protected by an RCB at the consumer unit - do I still need a RCB to the bath?).

Underfloor heating - I understand this should be connected to a switched, fused spur from the power ring.

For this I would recommend the running of a new circuit from the consumer unit to a small enclosure, water proof, under the bath. This unit should house TWO RCBO's, one (6A 30mA) for the Whirlpool Bath, and one (10A 30mA) for the Underfloor heating. In the consumer unit this circuit should be connected to a 16A 100mA RCBO.

By doing this you are ensuring that any fault in the bathroom stays there and does not operate the main RCD in the consumer unit, as you would lose your lighting if the unit would not reset.

Also, byt having two RCBO's locally, the fault will only prevent you from using that sub-circuit and also allow you to locate and identify a fault sooner.

The circuit can be installed using 2.5mm2 T&E, however I would use 4mm2 T&E.

 

[salem2000]

Why put the RCBO's in an enclosure under the bath, why not by the exsisting CU.

Surely it would make sense to put it where you can at least get at it.

 

[Tester]

The bathroom has two redundant circuits already one for the electric shower and the second for an emersion heater. Could one of these circuits be used?

The supplier of the bath also supplied a 25A 30mA RCCB could this be located somwhere more convenient like in an adjacent room or in the loft?

How would the two RCCB be wired to the new or reused circuit?

 

[Big_Spark]

The bathroom has two redundant circuits already one for the electric shower and the second for an emersion heater. Could one of these circuits be used?

The supplier of the bath also supplied a 25A 30mA RCCB could this be located somwhere more convenient like in an adjacent room or in the loft?

How would the two RCCB be wired to the new or reused circuit?

Either of these could be used for this purpose. I would use the shower circuit simply because it will be the bigger cable.

The enclosure for the two RCBO's can be mounted wherever is convenient, I suggested under the bath as this is local to both circuits, is accessible, or can be made so, it keeps the breakers away from prying fingers and saves the unecessary running of too much cable.

At the end of the location is up to you.

The RCBO's would be connected by linking the input side of the RCBO's using this cable, the outputs would obviously be to the individual circuits.

 

[Tester]

Thanks

You are obviousely an advocate of RCBO's in this installation is this the best device to use. I'm not chalenging your solution I'm just trying to understand under what circumstances each device should be used.

Don't mention plumbers - if you find a good one make sure you look after him.