Shower cable (again!)

[patrowles]

First off, great forum, and thanks to all involved for making it so entertaining and informative. I always get a good feeling when people with expert knowledge have the enthusiasm and generosity to share it.

I need to replace an electric shower, and am looking to get it done as cheaply as possible on the grounds that we are selling the flat (just coincidence that the shower should fail while we are doing the place up - we wouldn't have bothered, otherwise).

I have a very rudimentary grasp of plumbing and electrical wiring, and would not dream of attempting this job myself. However, I am also keen not to be "blinded by science" by anyone I get in to do it.

Through reading other posts here, I have picked up on the importance of having the right cabling, and I am trying to find out what the maximum power rating of the new shower could be with the existing cabling. I am assuming the existing cabling was adequate for the existing shower, as it did last for more than eleven years (it was there when we moved in).

The failed shower is a Triton T80, and the specification label on the bottom of the unit is too scaled up to be legible. I rang Triton and they said, based on its age, that it is probably a 7kW or 8kW model. I'm happy to have a more powerful one to replace it, and want to know how high I can go with the existing cabling. I gather from other posts that the length of the cabling is an issue, which brings me (at long last) to the crux of the matter.

As well as the usual on/off switch on the unit itself, the shower is controlled by a cooker-type switch (you know, like a big red light switch) sited on the wall outside the bathroom. I'd be surprised if the distance from this switch to the shower unit was even 1m. (N.B. The neon indicator on this switch still comes on when it is switched on, so I am reasonably confident that it is only the shower unit that has failed.)

So, if we did get a more powerful shower needing more substantial cable, is it only the cable from switch to shower that needs replacing, or also the cable from the mains fuse box to the switch? This would obviously have a bearing on the cost of the job, and consequently on whether I splash out on a more powerful replacement, or something equivalent to the old T80.

 

[Tom JE]

Funnily enough i just replaced my Triton T80 shower, mine was a 7kw which, by todays standards, is quite low. My shower was fed via a 6mm cable. First of all you need to identify what cable you have already. I went on the Triton website and found that it lists its latest models as equivelents to older models. I was able to use my original 6mm cable with this new Triton shower rated as 7.5kw.

http://www.tritonshowers.co.uk/index.php3

The rating of cable though depends on a lot of things such as the length of run from your fuse box, how its fixed etc etc. I do believe that if your cable wasnt big enough that the whole lot will need replacing, not just from the switch (i'm sure somebody will confirm that). As i said above though, as cost is an issue, i did manage to keep the same 6mm cable and upgrade to a 7.5kw shower that i am more than happy with.
I did find however that as an RCD was recommended (and my electrics were dated) it was a good idea to replace my consumer unit at the same time.

 

[didthathurt]

Upgrading can be simple but, there again, it can be quite difficult - depending on the incoming supply fuse, the consumer unit, the rating of the mcb and the size of cable already in situ. A 7kW shower can be powered through a 32Amp mcb and, in theory, a 4mm cable (depending on how the cable has been routed) - move to an 8kW shower and you are exceeding the mcb and cable rating. If your flat already has electric water heating and cooking and only a 60 Amp supply (as it may do depending on the age of the flat) you may end up exceeding the load of the incoming fuse and your consumer unit.

I hope you can see from the above that no question of this nature can be given a straight off answer. We'd need a lot more info to do so. Post back with, the age of the flat, what sort of consumer unit (fuse box) you have - makers name esp - what you have in the consumer unit (RCD?) and any rating information there is on the fuse/mcb that is protecting the shower circuit. Also, have a look at the cable and tell us what size it looks like it is.