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Two high-power appliances on a single 40A RCD

Former Community Member over 4 years ago

I have an electric shower installed on a 40A RCD, in a room adjacent to my kitchen. The shower is only used in an emergency - i.e. when our gas boiler is unable to provide hot water to our main bathroom. I would like to take a spur from this 40A connection to use for a new double oven, which is rated at 32A. Can anyone advise on a safe and legal way to do this, ensuring that only one of the two appliances can be connected at any one time?

0 Former Community Member over 4 years ago

On reflection he was pretty forthright and inflexible regarding other aspects of the work (i.e. the kitchen fitting stuff) - opting only for the priciest options, and insisting that other options were not viable. My instinct is that he was perhaps not the best person to have been advising me on this. Disappointing, as I found him via the British Gas "Local Heroes" site.
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0 mapj1 over 4 years ago

45A splitter look at the pic of one wired up. Designed to fit on top of standard or deep single socket box sunk into the wall. One in through the back box , two out on the surface.

Most commonly seen behind cookers to feed hob and oven from common cable. Do not put it in the bath /shower room !!

If you do find yourself tripping the breaker more than very occasionally then you will need to re-think and invest in 2 cable runs all the way to the board.
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0 Alcomax over 4 years ago

The screwfix forum says

433.1.1 [i] the rated current of the protective device is not less than the design current.

It is one thing to say something is not going to be used. It is still there and could be used. The kitchen fitter is being responsible; why should they take on additional risk?

The answer by Broadgage concerning "Shower priority unit" is a legitimate way to go. For legitimate, read sensible.

Circuit breaker as a "load limiter" is a bit rough; for the cavalier it may be a badge of honour , but really should have no place for installation work done for reward and done to some kind of standard.
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0 Former Community Member over 4 years ago

Hmmm....yes I can see what you're saying. I guess it's the distinction between "sensible" and "legal" that should have been made clear to me. I have no problem with a tradesperson telling me that something is not advisable, or something that they are not comfortable with. I do have a problem if they have incorrectly advised me that it is "illegal".
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0 Grumpy over 4 years ago

Alcomax:

It is one thing to say something is not going to be used. It is still there and could be used. The kitchen fitter is being responsible; why should they take on additional risk?

The answer by Broadgage concerning "Shower priority unit" is a legitimate way to go. For legitimate, read sensible.

Circuit breaker as a "load limiter" is a bit rough; for the cavalier it may be a badge of honour , but really should have no place for installation work done for reward and done to some kind of standard.

Well said Alcomax,I have been surprised by some of the previous posts. I consider it unthinkable that a professional would design a circuit that could be routinely overloaded and relying on the CPD to disconnect it. I'm with the kitchen fitter, I would refuse to do it too.
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0 AJJewsbury over 4 years ago

Kitchen fitter does not have a clue! I wonder which regulation that is? Answers on a postcard to the Screwfix forum.

That'll be regulation A.26 "A final sub-circuit having a rating exceeding 15 amperes shall not supply more than one point...." - although you have go back to the 14th Ed for that - so not quite a current requirement!

- Andy.
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0 Former Community Member over 4 years ago

I did actually suggest that some sort of 3-way switch (oven/shower/off) might be considered, but was told that this would not be "legal".

Thanks for all the feedback - it's given me a much clearer idea of what I should be considering.
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0 Sparkingchip over 4 years ago

I would refuse to do the job without additional equipment installed at the cooker and shower end of the circuit.

The kitchen fitter is being quite reasonable and the sensible thing to do is to install an additional complete new circuit for the cooking appliances.

Andy Betteridge.
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0 Sparkingchip over 4 years ago

Look at it the other way around, if asked to connect a new 8.5 kW shower to a cooking appliance circuit what would you say?

I would say no.

Just pay to have a new circuit installed for the cooking appliances and do a decent job.

Andy Betteridge
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0 Former Community Member over 4 years ago

A little context....I live in a townhouse, The consumer unit is on the ground floor, at the front of the house. The kitchen and shower room are on the 1st floor, at the back of the house. Running a new circuit would involve pulling up floorboards and almost certainly some cutting into walls and subsequent redecoration. Hard to see it costing less than £1000. The oven that we want to install cost £400 (which is the whole reason for the job).
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Two high-power appliances on a single 40A RCD

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