I have an 8.5KW shower installed in my bathroom but would like to have another 8.5KW unit in a new shower room in the attic. Can I run both showers on a 6mm ring back to a single supply fuse or will a separate supply need to be run from the consumer unit?
Electric showers running off the same circuit?
- Thread starter EdKap
- Start date
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Ring final circuits are for socket circuits, not 8.5KW showers!.
You could have a changeover switch so that one or the other shower could be used (not both at once) but that's not practical.
You'll be needing a new circuit for the second shower. Before that, you'll need soemone who have the knowledge to assess if your supply and the fuseboard are capable of supporting the extra load.
The new circuit will need to be installed to 17th edition regs and, of course, this is notifiable work so i suggest you find a local spark at www.competentperson.co.uk. He/she can do teh preinstall checks and look after all of the aspects of the install.
You could have a changeover switch so that one or the other shower could be used (not both at once) but that's not practical.
You'll be needing a new circuit for the second shower. Before that, you'll need soemone who have the knowledge to assess if your supply and the fuseboard are capable of supporting the extra load.
The new circuit will need to be installed to 17th edition regs and, of course, this is notifiable work so i suggest you find a local spark at www.competentperson.co.uk. He/she can do teh preinstall checks and look after all of the aspects of the install.
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I would imagine its a common problem for the CU not to be able to support that load these days, so many houses I see have less than 50 amps on their CU and with the amount of washing machines, dish washers etc people have if both them shower elements were on at the same time that would be a combined consumption of 17kw wouldn't it 
It's not difficult to do if you don't mind one shower being able to usurp the other if it's already running.
If you want to prevent that it's a lot harder - in fact I'm not even sure it's possible with just contactors. I tried once to design such a thing, and couldn't quite get it OK - as I recall it did work, except when the circuit lost power, both shower pulls were turned on, and then power came back. I think you'd need to go to something using more intelligence than contactors, eg a PLC.
A simple 40A BBFM DPDT switch will do the job, but assumes cooperation by the users.
If you want to prevent that it's a lot harder - in fact I'm not even sure it's possible with just contactors. I tried once to design such a thing, and couldn't quite get it OK - as I recall it did work, except when the circuit lost power, both shower pulls were turned on, and then power came back. I think you'd need to go to something using more intelligence than contactors, eg a PLC.
A simple 40A BBFM DPDT switch will do the job, but assumes cooperation by the users.
and assumes a suitable place to put the switch to suit both showers.
BAS, are you sure you aren't over-complicating things? I would have thought a contactor with its coil fed off the switched side of one isolator with NC contacts on the feed see of the other showers isolator, repeated for both showers, would do the job just fine. You'd never be able to have power to both showers at once as when one isolator is on, the contacts on the contactor fed from that isolator will open and remove power from the second isolator. The second isolator can't butt in on the first because the removal of power will render it unable to bring in the contactor that switches out the first shower.
Probably doesn't make much sense described in words!
I would have thought that too (but from memory I think you need 3 contactors) until I looked at what happens in the power-loss scenario I described earlier.
What if you did as electronics UK says but put a 1s timer in with the shower contactor which you don't want to have priority. Should get you over the startup after power fail scenario.
I'm sure I have seen some sort of current monitoring device which fits in a CU on here for use where two showers are installed.
I'm sure I have seen some sort of current monitoring device which fits in a CU on here for use where two showers are installed.
Probably something like this for the control circuit. The last shower to be used would have to have its isolator switch turn off to allow selection of either shower again.
Perhaps using three contactors is where your problem was. I'm finding it hard to imagine any situation where the solution I proposed earlier wouldn't work. Even with both isolators on after a power loss, it's absolutely impossible for both contactors to be on at the same time. Presumably it would come down to which one reacts quicker in such a situation, or perhaps (though I can't quite imagine how it would happen) get stuck in a situation where the contacts are just sitting there chattering.
A bit like your teeth would be as you stand in your shower, all covered in soap & shampoo when the power goes off cos user 2 has priority...
Or did you have in mind a design so that the first one to finish brushing their teeth gets power to their shower?
I can't understand it, don't people have hot water in their houses any more?
The latter. It would be impossible for one user to usurp power from the other until the first user has turned off their isolator with a simple 2 contactor system. An interlock system still isn't ideal, but most people would probably prefer not to have to pay for a supply upgrade.
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