Replacement Shower

[diynoob]

Currently have a Triton Ivory 2, don't know the power of it. What's the maximum kW shower I can get without rewiring? MCB Info:

Live=6mm²
CPC=2.5mm²
Rating=32A
Max Zs=1.44
R1+R2=0.05
Earth Fault Loop Imp=0.37Ω

Don't know if the cable is insulated but will be about 6m long.

Thanks

 

[wingcoax]

With 6mmsq cable the maximum is 8.5kw. ASSUMING it is 6.00.

 

[riveralt]

With 6mmsq cable the maximum is 8.5kw. ASSUMING it is 6.00.

With the information provided you cannot make a guess.
What is the cable run does it pass through insulation?
Assuming no insulation or other derating factors affecting the cable, on the information provided here you can probably just get away with 7.5kw shower.
But you would have to be guided by the manaufacturers instrucitons.

 

[diynoob]

Thanks. The cable runs up from the CU inside a plastered wall then under a bedroom floor to the shower switch in bedroom. Shower is on the other side of the bedroom wall. No trunking or insulation.

 

[riveralt]

Thanks. The cable runs up from the CU inside a plastered wall then under a bedroom floor to the shower switch in bedroom. Shower is on the other side of the bedroom wall. No trunking or insulation.

In which case the maximum shower you can have on the information you have provided is 7.5kw but you need to follow the manufacturers instructions.

 

[diynoob]

The manufacturers instructions say the current capacity for 6mm² is 47A.

Now, 230V x 47A = 10.8kW. Does that mean I can get a 9.5kW or even 10.5 kW shower? How did you calculate only 7.5kW?

 

[riveralt]

The manufacturers instructions say the current capacity for 6mm² is 47A.

Now, 230V x 47A = 10.8kW. Does that mean I can get a 9.5kW or even 10.5 kW shower? How did you calculate only 7.5kW?

7.5kw is derived from 7500/230v = 32.6 Amps.
Since, according to information you provided, you have a 32 Amp MCB and so that is the maximum you can have.
Incidentally, I don't know where you get the max Earth loop impendance figure from.
For an 8.5kw shower the manufacturers will require you to have a 40Amp MCB and insist that the circuit is RCD protected as well.

Since you will be changing the characteristics of the circuit then this job is notifiable if you live in England or Wales.

 

[diynoob]

Thanks. What I wanted to know though is what kW shower I can have without rewiring. I don't mind paying to have a MCB replaced and shower changed, it isn't going to cost me very much. I don't want the 6mm replaced because it affects the lounge and bedroom I've just decorated.

Its already RCD protected, the CU is only 6 months old. Assuming I will get the MCB increased to whatever is allowable with the 6mm wire, what kW shower can I buy?

PS the figures in the post are from the report the electrician gave me after replacing the CU.