steam shower wiring help

[stewart1875]

i've just purchased a new steam shower cabinet. the instructions say that i should remove the attached 3 pin plug and rcd that are there for testing purposes and connect to an isolated 13 amp spur.
question is ......... my old electric shower is on a dedicated circuit with a 32a rcd and has an isolator switch in my utility cupboard. 10mm cable runs through a pipe box to the attic and into the bathroom/old shower.
as the 10mm cable is too big to fit intio a 13amp spur is it permissable to run 10mm cable into a 30amp,3 terminal junction box then run a smaller cable ( 2.5mm ?) to spur ?
spur is going to be in attic and exsisting isolator in cupboard will be used.
thanks

 

[EFLImpudence]

Not sure of the regulations in Scotland. You should definitely contact your Building Control Office and find out if you need a warrant before starting this work.

I am assuming this new cabinet uses a plumbed shower control and NOT an electric shower.

You say the circuit has a 32amp RCD - I presume you mean a MCB (Miniature Circuit Breaker). However the new cabinet will have to have an RCD (Residual Current Device of 30mA) to protect the circuit and you and your family..

Electrically, though, you could still use the existing shower circuit from the consumer unit to the switch in the cupboard.
Remove the cable from the switch to the shower and replace with 2.5mm² twin&earth cable and connect to a Fused Connector Unit, fitted with a 13amp fuse, next to the switch then
EITHER - continue with 2.5mm² T&E to the loft and connect to the steam unit cable with a 20amp junction box
OR if the steam unit cable isn't long enough to reach the loft replace it with heat-proof 2.5mm² flex and run to the FCU.

I have given you what is probably the easiest way to connect this cabinet as there won't be anywhere in the bathroom to connect it.

HOWEVER, for your own safety please get the job done and TESTED properly by the correct procedures (regarding the regulations) and by someone who will KNOW if it is correct.

IT'S NOT WORTH TAKING CHANCES IF YOU'RE NOT 100% CERTAIN.

 

[stewart1875]

thanks ... thats cleared a couple of issues.
on other thing regarding the flex on the steam unit, it is quite short, is it possible to join in the bathroom, under the shower tray using an ip66 cable connector ? .. once cabinet is in place it will only be accesable using a tool, does this put it out of zone ?
i'm nor sure of regs in scotland but i intend getting it checked over once fiished
thanks

 

[EFLImpudence]

it will only be accesable using a tool, does this put it out of zone ?

Yes

under the shower tray using an ip66 cable connector ?

Yes, but if it is impossible to change the cable I would prefer to join it either with crimps, using proper ratchet crimper, or with soldering.
In either case stagger the joints and cover with self-amalgamating tape, first individually and then totally, and then with heat shrink. Joints made in this way do not have to be accessible.

Connect the new flex to the FCU first and run through the loft, keeping it well away from any loft insulation, and down in the bathroom. Before connecting it to the steam unit the whole circuit will have to be tested for - Continuity, Insulation resistance and Earth loop impedance and the RCD device will also have to be tested.[/quote]

 

[EFLImpudence]

pressed the wrong button.

If you do not have RCD protection at the consumer unit you can obtain FCUs that have an integral RCD.
I must emphasise strict adherence to the regulations (which in England require notification BEFORE you start).

If you do not have the correct test equipment and/or do not understand what the tests do or MEAN please employ someone who does.