what size cable??? please help!!!

[speakyboi]

hi,

I recently had my houe re-wired and know nothing about electrics. I need a new shower fitting and am unsure what size cable i have, my certificate reads as follows, but i dont have a clue what it means:

Shower: wiring type(A), number of points served (1), Circuit conductors: CSA, LIVE mm2 (6), CPC mm2 (4), max disconnection time (5), BSEN (60898/1), Type (B) Rating A (32), Continuity all circuits (R1+R2 = 0.11) insulation resistance line/neutral (200) line/earth (200), neutral/earth (200) polarity (tick), maximum measured earth fault loop independence Zs (0.24), RCD operating current (30ma).......

so from all that, i have updated my 7.5kw shower to an 8.5kw shower will that be o.k???

my electrician isnt available and cant remember what cable i had, he defintitley didnt put a 10mm in as it meant smashing a wall down so he re-wired the isolater switch instead. please help!!!!!

 

[ban-all-sheds]

Shower: wiring type(A), number of points served (1), Circuit conductors: CSA, LIVE mm2 (6), CPC mm2 (4), max disconnection time (5), BSEN (60898/1), Type (B) Rating A (32), Continuity all circuits (R1+R2 = 0.11) insulation resistance line/neutral (200) line/earth (200), neutral/earth (200) polarity (tick), maximum measured earth fault loop independence Zs (0.24), RCD operating current (30ma).......

so from all that, i have updated my 7.5kw shower to an 8.5kw shower will that be o.k???

Probably, but not necessarily - does the cable run in insulation anywhere?

cant remember what cable i had

6mm².

 

[electronicsuk]

The cable is 6mmsq. A 7.5kW shower is right on the limit for a 32A protective device, an 8.5kW is too high. However, depending on how the cable is installed, it may just be possible to use a larger protective device on the circuit. You'd need to consult an electrician.

 

[speakyboi]

not sure what you mean by insulated anywhere, it has casing around it if thats what you mean?

the box for the shower says 6mm2 so it all points to it being o.k......

 

[ban-all-sheds]

not sure what you mean by insulated anywhere, it has casing around it if thats what you mean?

I mean thermal insulation in walls or ceiling spaces or lofts - if it has insulation around it, even partially, this affects how much current it can carry.

the box for the shower says 6mm2 so it all points to it being o.k......

It's not OK.

Firstly the box for the shower is ignoring the fact that depending on where the cable is installed it might have a capacity of less than 24A.

Secondly, as electronicsuk pointed out, and I failed to consider in my initial reply (sorry) you've got a 32A breaker on that circuit. An 8.5kW shower will draw 35-37A, so even if the cable is OK for that much current the breaker is not. And you can't just replace the breaker with a higher rated one without knowing how the cable is installed because the breaker may not have a higher rating than the cable. Depending on the sizes available for your make of CU, the next step up might be 45A, not 40, and that is borderline for a 6mm² cable.

Basically you need to stick with a 7.5kW shower, or get an electrician.