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Hi guys, been asked to change a shower, customer wants to put a 9.5kw in place of 8.5kw. Supply is db to dp sw 6mm t+e (7m) then sw to shower 10mm t+e (7m). I was thinking 6mm should be upgraded to 10mm but customer doesnt want the mess! What do you guys think?
 
what reference method for the 6.0mm? if it's method C then you're OK. if covered in insulation crap, then either move the crap or upgrade cable to 10mm.
 
Tell them they are Scottish and lot to be whimps and stick with a 8.5kW... Problem solved...
 
The 6mm is clipped under a floor but no insulation but it drops down to the db bunched with other cables. Its one of those ones that its borderline, the cable can take take it but id still prefer it to be 10mm
 
not if you put it on a 32A MCB.
 
not if you put it on a 32A MCB.

Assuming its not already, and changing the protective device means a new EIC.

pcam, a 9.5kw shower is what its been rated at 240v, at nominal voltage (230v) its 8.7kw check the box. so thats pretty much like for like, advise cable is upgraded before they put a 10.5 in next time.......looks like they are heading that way.
 
it's nominally 39.5A. bet if you clamp it , it won't pull more than 35A.
 
Using a 6mm T+E cable, bunched with other cables, and/or running it on a 32Amp CB are both bad design practices, and almost certainly will not comply with the Regs.

Separate the cable from the others, and it may then comply, but not on a 32A CB, use a 45 or 50A.
 
433.3.1 (ii) will apply to an electric shower,if it has fault protection, hence no need for overcurrent protection.
 
now, that is a get out of jail free card. complies with regs., but is it good practice?
 
Thanks guys, i told them that a 9.5kw could go on but that id feel more comfortable if it was on a 10mm cable, they have opted for a decent quality 8.5kw and want the cable upgraded at a later date when they are redecorating.
 
now, that is a get out of jail free card. complies with regs., but is it good practice?

Yes.
This is a semi-regular subject on the IET forum.
IET Forums - Mistake

Think about a spur off a RFC. The cable of the spur could be overloaded - limit of ~20A, but potential load of 26A. However, in reality, the load will never reach that amount, hence safe to run a 20A cable protected by a 32A CB.
Same goes for a shower, protected by a 50A CB, it has fault protection from the CB (and RCD if fitted), but does not have overload protection.
The characterisitics of the load make it very unlikely that it will draw more than its quoted power, so, if the cable can hold the quoted power, the CB does not have to protect the cable, but it should give fault protection, which a slightly higher rating CB will give anyway.
 
result. common sense prevails. why anyone would want a shower above 8.5kW cracks me up. a shower is a chore, not a pleasure. just to get the dirt off and get out. now, a jacuzzi bath with a large scotch in 1 hand and a king size B&H in the other, now, that's a pleasure!.
 
Assuming its not already, and changing the protective device means a new EIC.

pcam, a 9.5kw shower is what its been rated at 240v, at nominal voltage (230v) its 8.7kw check the box. so thats pretty much like for like, advise cable is upgraded before they put a 10.5 in next time.......looks like they are heading that way.

The problem with that little gem, is that the supply isn't going to be 230 Volts is it, if anything it's going to be in excess of of 240 Volts!!

I don't really understand some of the electricians on here, It's YOU the electrician that make the decision if a cable or whatever is of a suitable size or suitable for purpose, NOT the untrained client. If they are not going to listen to you ....fine, Walk away!! At the end of the day, it's going to be your arse on the line, not the tight as a ducks arse in cramp client!! ...lol!!
 
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