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Two high-power appliances on a single 40A RCD
Former Community Member
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?
From what is being described, it would seem wise to me to assume that the ownership of the property or the way in which it is currently used could be changed, with many more occupants for example. Therefore, something that relies on existing patterns of use, or a “procedure” by a person with some knowledge would potentially concern me. A judgement has to be made about risks that could reasonably be foreseen, these might include the risks of having to reset a protective device, certainly not recommended having emerged from a shower.
When I was originally trained on the regulations (14th), it was emphasised that the regulations did not preclude alternative methods as designed by a suitably qualified person. I won’t get sucked into the technical argument here, but what it illustrates is that there are a variety of different approaches, seeking to balance cost with risk. Ultimately the client has to pay for it and it may seem unreasonable to place upon them the cost of what might or might not occur in future, if the risks are relatively low. If it were my home, then I would make my own judgement and be very wary of anyone who insisted that expensive additional work was required. The problem might arise if an inspection is needed, because the design isn’t documented, so the inspector is potentially left “holding the baby” if something goes wrong. This might involve someone falling down stairs or having some other mishap, because of the design of the installation.
The additional issue was raised of the difference between a “trade” and a “profession”. Perhaps the answer lies here https://www.youtube.com/watch?v=9tXBC-71aZs as much as anywhere. This is an IET forum, so members of the IET sign up to a code of conduct and those who register with Engineering Council have a further additional obligation to maintain a standard of competence appropriate to their post-nominal and to act within it. There is certainly no reason why someone who meets the Eng Tech standard and is engaged on electrical installation work should not be a highly professional expert.
I won’t rehearse here what the differences might be between the three “types” codified by Engineering Council. However for simplicity in these type of circumstances, I would expect a professional Technician to rely more on compliance with regulations, whereas an engineer should evaluate and provide justification ,with reference to regulations as necessary. Each needs to accept responsibility for their actions.
The extent that having engaged in higher education makes a difference versus practical experience, it is probably most evident in formal design and “reporting”. So for example, on a recent extension home extension project, I hired an architect, a structural engineer, builders, a plumber, and an electrician. The first two gave me documentary evidence and satisfied public bodies (eg planning and building control), the first builder improved on the plans in practice, although sadly eventually lost productivity, the plumber has left me with an impressive and quite complex mini plant room to play with. The electrical work was probably the most straightforward, but it was quite a faff getting it certificated for Building Control , after I had to finish off the job myself. Scale this up to a major project and we have a “professional team” responsible for perhaps spending hundreds of millions of the client’s money.
From what is being described, it would seem wise to me to assume that the ownership of the property or the way in which it is currently used could be changed, with many more occupants for example. Therefore, something that relies on existing patterns of use, or a “procedure” by a person with some knowledge would potentially concern me. A judgement has to be made about risks that could reasonably be foreseen, these might include the risks of having to reset a protective device, certainly not recommended having emerged from a shower.
When I was originally trained on the regulations (14th), it was emphasised that the regulations did not preclude alternative methods as designed by a suitably qualified person. I won’t get sucked into the technical argument here, but what it illustrates is that there are a variety of different approaches, seeking to balance cost with risk. Ultimately the client has to pay for it and it may seem unreasonable to place upon them the cost of what might or might not occur in future, if the risks are relatively low. If it were my home, then I would make my own judgement and be very wary of anyone who insisted that expensive additional work was required. The problem might arise if an inspection is needed, because the design isn’t documented, so the inspector is potentially left “holding the baby” if something goes wrong. This might involve someone falling down stairs or having some other mishap, because of the design of the installation.
The additional issue was raised of the difference between a “trade” and a “profession”. Perhaps the answer lies here https://www.youtube.com/watch?v=9tXBC-71aZs as much as anywhere. This is an IET forum, so members of the IET sign up to a code of conduct and those who register with Engineering Council have a further additional obligation to maintain a standard of competence appropriate to their post-nominal and to act within it. There is certainly no reason why someone who meets the Eng Tech standard and is engaged on electrical installation work should not be a highly professional expert.
I won’t rehearse here what the differences might be between the three “types” codified by Engineering Council. However for simplicity in these type of circumstances, I would expect a professional Technician to rely more on compliance with regulations, whereas an engineer should evaluate and provide justification ,with reference to regulations as necessary. Each needs to accept responsibility for their actions.
The extent that having engaged in higher education makes a difference versus practical experience, it is probably most evident in formal design and “reporting”. So for example, on a recent extension home extension project, I hired an architect, a structural engineer, builders, a plumber, and an electrician. The first two gave me documentary evidence and satisfied public bodies (eg planning and building control), the first builder improved on the plans in practice, although sadly eventually lost productivity, the plumber has left me with an impressive and quite complex mini plant room to play with. The electrical work was probably the most straightforward, but it was quite a faff getting it certificated for Building Control , after I had to finish off the job myself. Scale this up to a major project and we have a “professional team” responsible for perhaps spending hundreds of millions of the client’s money.
