Two electric showers running at the same time (in the same house?)

BatCat

Hi!
We're renovating a house and have planned for two electric showers (one in an en suite and one in the bathroom). The electrician has told us we'll need some form of complicated device otherwise should the showers ever run at the same time we'll blow all sorts of circuits.
Anyone ever encountered this sort of thing before? House is being completely rewired and bathrooms etc. installed from scratch. The showers are going to have to be electric but we don't want anything that will be so powerful it will blow you to the back of the wall but we seriously don't think we can control whether there will be two people in the shower at the same time.
Thanks,
BatCat

WestonDave

You need to check your main supply fuse - this can be 60A or in newer houses 100A (and I suspect as it is dictated by the size of the supply cable coming in, its not a simple matter to upgrade it if you have the lower one without a lot of digging up!). Whatever it is rated at, is the maximum current your house as a whole can use at any one time.

Every kw of power your appliances uses draws nearly 4.2A - so 2 8kw (its hard to get an 8kw shower as most are now higher power) showers running at once is 16kw, which equates to 67A - in other words if your main supply is 60A, your supply fuse is toast as soon as that second shower is switched on. I have never blown one, but I'm guessing its a National Grid job to replace it, not your local sparky.

The other point is practicality - instant heat electric showers are pretty much controlled by water flow - try and run two at once and neither will get enough water (unless you have ridiculous water pressure), it will go very hot and then cut out, before resetting and trying again - in terms of what comes out it will cycle through cold, warm, stupidly hot and back to cold.

JackRichardPT

You will also need two pumps, aswell as two cold water pipes coming straight from the cold water storage cistern, which involves the two seperate circuits, its straight forward plumbing side, the electricians you will need a certain breaker though

macman

JackRichardPT wrote: »

You will also need two pumps, aswell as two cold water pipes coming straight from the cold water storage cistern, which involves the two seperate circuits, its straight forward plumbing side, the electricians you will need a certain breaker though

The OP was asking about electric showers, not power showers.

JackRichardPT

Most electric shower being installed under the 2010 water reg's 6900 have to have small impellor pumps to boost the water rate on all electric showers

buyitall

We have 2 electric showers, one upstairs and one downstairs. The second one was fitted last year when we had an extension, and we run both of them at the same time without any problems.

macman

OP is your main supply 60A or 100A? That seems to be the limiting factor here (along with the mains pressure of course) And what kW power rating showers are you intending to install?
The domestic circuitry isn't the issue, as each shower will require it's own dedicated circuit from the CU with it's own overload protection. But if the load exceeds the capacity of the service fuse, you can't do it.

eco-friendly_2

JackRichardPT wrote: »

Most electric shower being installed under the 2010 water reg's 6900 have to have small impellor pumps to boost the water rate on all electric showers

What!

:rotfl:

BatCat

Hi Folks,
Excellent!
Thank you WestonDave for the clarification.
My OH discussed it with the electrician and was utterly confused earlier. This is much clearer! Our house in 60a and 1930s.
Any idea if there is anything we can do? We have two small boys now but I could just see them totally ignoring me when they're older and showering away like fiends.
Thanks,
BatCat

macman

Is it possible to fit a relay switch so only one shower circuit can be live at one time? With a 60A supply I can't see any way around it, even 2x 8kw showers are going to exceed the limit.
But might be better to consider the water pressure aspect first.

1984ReturnsForReal_2

macman wrote: »

Is it possible to fit a relay switch so only one shower circuit can be live at one time? With a 60A supply I can't see any way around it, even 2x 8kw showers are going to exceed the limit.
But might be better to consider the water pressure aspect first.

Or have one thermostatic pumped shower or a conventional one.