SHOWER SUPPLY

[senior]

Right i have a 10mm2 cable running 12 meters from CU and wondered what my limitations were for an electric shower.
I had the cable installed in a recent re-wire, my sparky said 'it would be big enough for the most powerfull shower.
However since then, after doing a bit of research, have found that some require 16mm2.
I could do with a little advice on what to buy, i have seen a nice shower but its 10.8KW and am not sure if its too big for my cable?

 

[mapj1]

Does the cvable pass through insulation, or is it in free air? This affects its maximum heating, and therfore thermal rating.
Both cases are handled quite well here
http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

If you get stuck, come back, and describe where the cable is routed
regards M.

 

[senior]

Does the cvable pass through insulation, or is it in free air? This affects its maximum heating, and therfore thermal rating.
Both cases are handled quite well here
http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html

If you get stuck, come back, and describe where the cable is routed
regards M.

The cable just runs straight along under floor boards and up the centre of a partition wall which has know insulation in it.

 

[mapj1]

Then looking at the calculator,
1) clipped direct or free hanging in a well ventilated partition, over 12m that cable is good for ~14kW (~60A) and would drop 3 volts or so.
2) If it was enclosed in trunking then that rating would fall to about 11KW (say 48 amps)
3) If it was in a fully lagged wall then the max would be about 9.5Kw, (say 43A )
I think with that in mind, you will be OK, for any normal shower, and certainly the 10.8KW you have your eye on. Just don't insulate that wall or the floor void !
regards
M.
PS in practice, many shower installations work fine with slightly undersized cables because the load is not constant, and not on for long enough to allow things to heat up significantly and secondly many makers tend to be guilty of 'specmanship' in quoting the ratings. However, you dont need to worry about that, you can shower 24/7 if you can afford it and remain in spec.

 

[senior]

Then looking at the calculator,
1) clipped direct or free hanging in a well ventilated partition, over 12m that cable is good for ~14kW (~60A) and would drop 3 volts or so.
2) If it was enclosed in trunking then that rating would fall to about 11KW (say 48 amps)
3) If it was in a fully lagged wall then the max would be about 9.5Kw, (say 43A )
I think with that in mind, you will be OK, for any normal shower, and certainly the 10.8KW you have your eye on. Just don't insulate that wall or the floor void !
regards
M.
PS in practice, many shower installations work fine with slightly undersized cables because the load is not constant, and not on for long enough to allow things to heat up significantly and secondly many makers tend to be guilty of 'specmanship' in quoting the ratings. However, you dont need to worry about that, you can shower 24/7 if you can afford it and remain in spec.

Cheers Great help

 

[ban-all-sheds]

you can shower 24/7 if you can afford it and remain in spec.

But you will go a bit wrinkly