my last shower was a 6.5 kw the plumber told me that this is all i can use is this true as i cant find one?

Question

6.5 kw showers dont seem to be on sale anymore so i wanted to know could i use a 7.0kw or woukd this be dangerous

Answer 1

Surprised he should say this. The only thing I can think of is, that your water pressure is insufficient to supply a more powerful shower. Or then again, the cable supplying the shower isn't heavy enough to supply a greater current. But I'd find that hard to believe because he could always run another cable.
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You might want to ask another plumber's advice, but it is hard to get one!! Look around for a Polish plumber, they are much cheaper.

Thinking about it, I feel you must have put the plumber off in some way and he didn't fancy the job, (mnot enough cash in it)so he was just being difficult. Go to another, more helpful plumber. Always make it plain you will be dealing in cash, this the preferred method of payment for plumbers.

Answer 2

Most likely it is a 30A cable, which is the limiting factor. Since UK supply voltage is 240V, the maximum power of a shower that you can use is 30 x 240 = 7200 W, i.e. 7.2kW. Hence, a 7 kW shower should be OK. Check your fuse board, and the fuse (or circuit breaker) will tell you the power rating you can have.

If you want to, you can get the wire taken out and a 45 A cable installed instead. This will allow you to go up to a 10.5kW shower. The cost of this is likely to be much more than the cost of the replacement shower though.

If you don't have it already, you should install a circuit breaker (MCB) to the same current as an existing fuse (Usually these are rated at 32A, and are equivalent to a 30A fuse). You should also incorporate a residual current device (RCD) into the circuit. Unfortunately, this may mean replacing the fuse board. If you get an electrician in to do the work, I believe that they are now required to upgrade the system to include for these items, if not already included, under the 16th edition of the IEE regulations.
In addition, I think that you may be required by law to get an electrician to either do the work, or to certify the work once complete, under the latest edition of the building regs (Section P), that came into effect on 1st Jan 2005. It may be exempt as 'minor works' under Appendix A, but I'm not sure if showers are included in this - best to ask your local authority.

Answer 3

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RE:
my last shower was a 6.5 kw the plumber told me that this is all i can use is this true as i cant find one?
6.5 kw showers dont seem to be on sale anymore so i wanted to know could i use a 7.0kw or woukd this be dangerous

Answer 4

It could be because of pressure but unlikely - I would think the reason he said what he did was bcause that is the max wattage that can be connected to your fuse board within running a new fused spur or replacing the fuse board - if you fit a higher kw shower it would just blow the fuses every time perhaps. Being that this work would be done by an electrician, not a plumber, and could be expensive, I assume is why he says he can obly fit a 6kw maximum shower. Why not call a plumber for an estimate for a new shower and see what they say ????

Answer 5

Usually the plumber would defer that to the electrician.
If you look at your supply box, there should be a main fuse. See what amp rating that is for. Then see what amp rating the circuit breaker for the shower is. You can check the specs on the new shower to see what is required.
I know my house is 60 A supply but I still installed a Triton T90SI 8500 W. The box said I need a larger supply. I rang an electrician and he told me just do it. You can always consult an electrician.

Answer 6

I would be very surprised if your existing/old shower wasn't on 6mm flat twin and earth cable, in which case a 7kw shower should be ok for replacement. The current carrying rating of cable in relation to it overheating changes depending whether it is surface fixed, in conduit, or set in plaster etc.Get an electrician to take a look at the cable/fuse/pull cord isolating on/off switch. He will be able to advise much better than some plumbers.

Answer 7

It depends on your cab;le size, if its 4mm then 6KW is your limit.

7.0KW is not a great variance, i would ask him why you need a 6.5Kw one.

The calculation in the above answer is slightly flawed. You cannot just multiply current and voltage to get power in an AC circuit, you need to take into account power factor. For an induction heating element ( shower ) this will reduce the power availble from any given current limit on a cable. sO the calcualtion of 7.2KW could well be less than 7KW when you take into account power factor.

If you're wiring is old ( 4mm shower cable woudl be quite old ) then it might be best to change it...soem decoratino required but you'd have a decent shower heat and solve the problem for the future.

Answer 8

You will have to establish the size/current rating of the existing cable, length of cable and the voltage drop for the circuit, also that the isolator switch and circuit protective device is suitably rated. There are also additional requirements for showers pertaining to earthing and bonding, earth loop impedance and disconnection times to name but a few.

I suggest you contact a decent electrician for advice, otherwise you risk fire and death.

(Most popular showers nowadays are from 9.0 to 10.5 kw) I think you would find a 7kw not much of a shower if you could find one.

Dont forget plumbers are not electricians and vice versa!

Answer 9

He probably meant you coulnd't go anymore powerful due to the thickness of the electrical cabling (more kw's, thicker cable required).

I'm not an electrician or a plumber, but Im pretty sure on this. Might be worth consulting an electrician as I'm fairly sure that its your cable that is the problem.

Answer 10

If your water pressure is sufficient to run a 6.5kw shower then it is sufficient to run a 7kw shower. You will need to replace the cabling and the trip switch (fuse) on your fuse box to accommodate the higher power demand. Use a British plumber if you can - standards of workmanship in this country tend to be higher.