Can this CU manage an electric shower?

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Jonmyates

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Good morning all.

Having updated our bathroom we'd like build in a shower.

Before we commit on how (plumbed vs electrical) I wanted to see if our CU would be up to the job (with the inclusion of an 40a MCB where the space is) of an 8.5/9.5Kw electric shower or if it would be more extensive. I've attached a picture of the CU.

Please be advised that I will be getting an electrician to do the work, however due to our location being a bit remote I don't want to invite a sparky out only to discover within a few mins it can't be done or very expensive to make it happen - I'd hate to waste their time.

Any comments welcome.

JY
 

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You can add the bits required, however I would say the house needs a rewire because some one has put cavity wall insulation in the void where the cables run so they could over heat with any high load.

So since a thermostatic valve gives you a better shower anyway it is not worth considering the work required to either rewire or remove the insulation before adding the extra load.
 
Hi Eric,

Thanks for this.

Would updating the CU be an option or is it the actual insulation in the cavity that's the issue?

Thanks
 
Those old Wylex boards have a maximum current limit on them so It would not be recommended that you have one of those instant mains-water pressure showers.
Also that Ottermill RCD looks ancient (I would need to see the rating of it to comment further - a better photo of that please) it may not be the correct rating to protect you in an electric shower.

Secondly I would be concerned by that polystyrene clinging to the cables. Certain poly substrates can eat in to PVC cables.
May need a rewire and certainly a new modern consumer unit before proceeding.

Thirdly - you need to find out what size supply you have there before adding another 40amps to the incoming load. You look like you are in a rural location, perhaps with an overhead supply?

Overall you need to think about why you need one of those showers. If you have a gravity type water system (cold water tank in the loft) then you'd need to plumb the mains pressure supply into the bathroom. In those situations it is often better to install a shower pump and use the existing H&C water. A pump uses only a few amps and will not need a separate circuit.
 
Hi Taylor.

Correct, we're rural and have overhead supply.

RCD picture attached.

Our reasoning for an electric is that we have a poor boiler and so sometimes don't have hot water and as we have 2 young kids its simply not an option. Having an electric means hot water on demand.

Thanks again,

Jon
 

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As above, you'd need to check how much your max current can be.
Your service fuse could well be only 60amp, so plonking a 40A shower on there is going to stop you using much else at the same time.
If it is big enough, then you'd need a separate mini consumer unit to supply the shower itself, or a complete new consumer unit.

This would need doing by a registered electrician and I recommend you have one come and tell you what your options and the costs might be.
Have him use an RCD tester to check that the old Ottermill box is still up to scratch. It is the safety barrier for you and your family.
 
then you can get hot water even when your boiler is broken. Are the cylinder and hot pipes well insulated?
 
Taylortwocities said:
Have him use an RCD tester to check that the old Ottermill box is still up to scratch. It is the safety barrier for you and your family.
Click to expand...
It's not totally clear, but does that label not say that the IΔn of the RCD is "0.3A" (aka 300mA)? If so, even if it were "still up to scratch", it would presumably not represent much of a "safety barrier for the OP and his family".

Kind Regards, John
 
Hi, yep there's an old boiler (Ideal Mexico - circa 1975).

The issue is that the flow is low from hot and very high from cold. So what happens is that the water goes very hot to very cold.

Having electric would better regulate this variance.

Thanks
 
Jonmyates said:
The issue is that the flow is low from hot and very high from cold. So what happens is that the water goes very hot to very cold.
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Do I take it that this is a 'vented' system with the cold water coming from a storage tank? If so, I think that what you describe could only really happen if there was some inadequacy (pipes too small or 'furred up') in the hot water supply pipes.

If the hot water is coming from the cylinder but the cold water from the 'mains' (not from a storage tank) then one would expect what you describe.

Kind Regards, John
 
Jonmyates said:
The issue is that the flow is low from hot and very high from cold. So what happens is that the water goes very hot to very cold.
Click to expand...
you mean in the shower?

that's common, it's almost always due to unbalanced supplies where the hot is at loft-tank pressure and the cold comes of the incoming watermain. It's a simple plumbing error. The usual solution is to run a cold pipe from the loft tank. I've found it varies with district, in some parts of the country bathroom cold taps are mostly fed from the loft tank, and in others, mostly from the watermain.

If the bathroom is upstairs it's not usually difficult to run a pipe through the ceiling into the loft.

You can add a shower pump, if you want. The volume of hot water from the cylinder will be greater than from an electric shower, but the pressure lower.

edit
too slow!
 
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