Electric shower wiring

[james26]

Hi,
First a little background information.

Around 15 years ago we had an extention built to turn a small downstairs toilet into a shower room.
At the same time a lift that goes through the ceiling was put in another room, the lift was powered from a socket.
A RCCB was fitted and the shower and the socket (lift) were connected to it.

Ok, so recently my mira electric shower (8.7kw) died and i decided to replace it with a cheap triton (8.5kw) from argos.
I went to fit it today and discovered that due to the positioning and components of the shower unit, the electric cable won't reach the terminal in the new shower.

So no problem really i just need to get a new cable length to run from the switch to the shower and all should be good.

The cable used to connect the shower is 15mm T & E. Thats 15mm from RCCB to switch, then 15mm from switch to shower.
Total length of cables is approx 10m.

The cable that they installed to power the lift through the socket is far smaller at 6mm.

So my question is why was 15mm T & E cable used, and where can i get some?

Thanks!

 

[Spark123]

15mm is not a standard size of cable, how are you measuring it?
The size is the cross sectional area of the live and neutral copper conductors, sometimes if you are lucky it is written on the cable.
Otherwise, can you beg or borrow an offcut of 6mm to see if it is the same size?

 

[james26]

The cable is the flat type, I measured across the flat side which is 15mm.
The cable is plain white with nothing on it.

 

[Spark123]

15mm is about half way between 6mm T&E and 10mm T&E.
Like I said, you could do with an offcut of cable to compare the copper conductor sizes.

 

[james26]

Ok, so i guess i could just get some 10mm T&E and use that from the switch to the shower?

I'll take a cutting with me to check the copper thickness.

 

[Spark123]

You could, but beware that this may mislead someone carrying out work in the future that the whole circuit is in 10mm when it may not be.
On the other hand, if you take the cable with you and you can compare it in the shop then you shouldn't go wrong.

 

[james26]

Thats a good point, thanks for your advice, i'll go down the shop tommorow and see what i need

 

[1john]

If the earth is a solid core and the line and neutral are stranded then it is more than likely 6mm, if the earth is also stranded then you prob have 10mm, 15mm across isn't big enough for 16mm and is too large for 4mm.