Shower switched through light switch

[Desie]

Guys

Give me your professional opinion on what I have found.

40A breaker
9Kw shower
10mm cable at both the shower and the CU
Isolator switch is one of a 3G bank of switches on the outside wall of the bathroom with the other two operating the bathroom lights.
The cable behind the 'shower' switch is no bigger than 2.5mm and yet I can't find any junction point anywhere. The cable goes sideways through a stud wall support. I have punched a hole in the base of the stud wall and the 2.5mm does not appear to go down under the floorboards and there is no evidence of any large load cable in the attic.

The bathroom looks like it's been re-fitted in the past few years and is surrounded by stud wall.

When I realised the 3rd switch was for the shower, without looking behind, I assumed there was at least a 6mm cable there and my intention was to split the switches with a 45a 2P switch and a 2G 2W side by side. Imagine my shock when I took the switch cover off.

 

[MasterAbacus]

Well if you have 10mm at the CU and 10mm at the shower, then you should have a switch where the 10mm is double pole switched.

Take a picture of the so called shower switch, and one of the wires inside so we can see whats going on....

Surely the 2.5 would just burn out if it was switched, Unless the 2.5 is actually switching and electrical 10mm double pole switch, hidden somewhere...MMMMmmmm

 

[RF Lighting]

We definatly need photos of this one.

 

[dannyboi2003]

Hopefully there's a contactor hidden away somewhere

 

[Desie]

Abacus

A\switch switching a switch somewhere? I never thought of that one.
Surely though the 2.5mm cable would still be carrying 40A and therefore a fire risk?

 

[RF Lighting]

Is the actual shower unit wired in 10.0mm²

If the light switch is switching a contactor then this cable will be carrying virtually no power.

If not then the cable will be seriously overloaded, and poses an immediate fire risk.

I am concerned that the cable at the switch is 2.5mm²

Normally control circuit wiring does not exceed 1.5mm²

 

[securespark]

If not then the cable will be seriously overloaded, and poses an immediate fire risk

It's only 12A over... Doubling over the copper in the terminals should see it right.....

BTW, I AM KIDDING!!!

 

[Desie]

Guys

The previous owner has pointed out a 'Contactor coil' which is switched from the 10a switch.

I've never come across a domestic shower using one of these.
Are they common?
How do they work?

I have also just read an article on the web that says that they could be a fire risk if left energised. Is this true?