Shower cable advice please?

[nomiracle]

This is my first post in these forums and I hope that someone can help me

My power shower has packed up and I ideally want to fit an electric one instead, I can do all the plumbing no problem but I've looked at the wiring and what I've got is: 2.5mm twin and earth coming from the shower in to the loft, back down to my airing cupboard into a 'Legrand' 40A/30mA (RCD i think or could be RCD/MCB but doesn't say it on it) then into what looks like a normal 230v lightswitch then I presume it goes to my 'old style' fuse box as it dissapears away again into the loft but in the direction of my integral garage which houses the fuse box.

Electrics aren't my thing but I do know that for an electric shower I'd need at least 10mm cable to the fuse box (and of course a double pole 40A ceiling switch between the shower and the 'MCB') Am I correct with this or is it possible to use a low Kw output electric shower with this setup? On the other hand I'm not sure what output the current power shower is although I know it's a very small one (Bristan Cascade) but was the wiring suitable for that one and if so could I just replace like for like?

I'm trying to do this within a small budget and yes I know you've heard that before! But I won't do anything if there's a risk and so thats why I thought I'd beg for a couple of minutes of someones time!

I'd actually gone this morning to buy a shower that was on offer one day only but thought I better re-check the wiring when all of this alerted me, I'm absolutely gutted as I start a new job on Tuesday that requires me to start at short notice in the middle of the night and so really need a working shower.

Please could anybody help dig me out of this hole?

Thank you.

 

[Doc Hudson]

Welcome to the forum. I think we first need to be clear about what you call a power shower. A power shower will have two water supply pipes, one hot, one cold and an electric pump to increase the flow of water. This pump is a very low power device compared to the heating element of an Electric shower. If you only have one cold supply pipe then it is just an electric shower. Some electric showers do not require 10mm cable, but there are a lot of checks that need to be done to establish exactly what you need. Power rating of new shower, cable lengths, cable routes, type of building insulation the cables pass through. the type and condition of exsiting earthing arrangments and incoming supply capacities and max load of exsiting fusebox and what the manufactures instructions require.

The work will also need to be tested and certified using a calibrated test meter, then it will need to be notified to your local council building control dept, for a Building regs part P compliance certificate. If you are not a registerd electrictian or do not have access to appropraite test meters the cheapest solution on a low budget would be to get a registered electricin to come and install & certify the work for you. You can do notification youself but most councils charge a lot for them to come out and test the work for you.

Some people just go and do the work without any of the correct paperwork to verify that the alterations are electrically safe. Whatever you chose to do, remember electric showers and electric cookers are typically the two most powerfull items connected to a domestic fusbox. incorrectly installed could cause serious fires or shock. Hope that is of some help.

Doc H.

 

[nomiracle]

Hi Doc, thanks for your reply yes its definately a power shower thats installed and after what you've said I'm assuming that the cable installation I have was correct only for a power shower. I'm now possibly thinking of just installing another power shower due to time constraints and get a qualified electrician at a later date to refit for an electric shower. Thanks for your help and you've certainly made me realise what's involved!

Mark

 

[Doc Hudson]

Hi Doc, thanks for your reply yes its definately a power shower thats installed and after what you've said I'm assuming that the cable installation I have was correct only for a power shower. I'm now possibly thinking of just installing another power shower due to time constraints and get a qualified electrician at a later date to refit for an electric shower. Thanks for your help and you've certainly made me realise what's involved!Mark

If you already have a working power shower and its associated supply pipes and water tanks, I would stay with power showers. Personally I would think it a backward step going to electric. The overall running costs will be higher for electric showers over its lifetime compared to the running costs of a good power shower. And you should get far better water flow rates with mixer or power showers compared to electric. Electric showers used to be the quicker and cheaper option for builders to add to a house rather than getting the plumber to do a bit more copper pipe. But with modern plastic pipe fittings -vs- the cost of 10mm copper cable, I would guess a new installed power shower could be almost as cheap as a new electric shower.

Doc H.

 

[hfalkner]

We used to have a very trusty electric shower fitted along the tiled wall complete with glass screen. It served a purpose and worked really well, but it never really occured to me the difference between an electric and mains fed power shower until I tried my brothers. Wow. Long story short, I ended up changing our water system to a fully fitted Megaflow system, all bells and whistles. This allowed me to fit one of these fully thermostatic steam showers complete with power shower.

It was a significant cost, and admittedly was done over a long space of renovation time.. But oh so worth it.