Range Cooker Connection Refusal.

I fully understand the points you are making Graham, and it seems to have touched a nerve with everyone. However BS7671 is NOT the place to attempt to fix design difficulties with appliances, and we keep trying to do it, particularly with EVs at the moment!

I see where you are coming from with your element point, but this fault is really not very dangerous is it? If the element gets a fault in the centre, it will take twice the current and get 4 times the dissipation in the half section which will rapidly lead to melting of the element. This current will not give a dangerous volt drop on the Earth connection. You can calculate the worst-case fault position but it is very unlikely to raise the Earth voltage for very long to a dangerous potential (>50V). The RCD is thus protecting against an unlikely scenario, that is not dangerous, the CPD protects the high current cases. I have no objection to fitting RCDs, but is this really a case where BS7671 should take over, I think not?

Wall warts are a particularly bad case, but the two types are both pretty much intrinsically safe to the user, transformer ones by the primary winding (usually less than 1A fusing capacity) and the switch mode ones by component s or tracks blowing open circuit. The lack of fusing in other appliances is probably because the UK has much higher rated socket circuits than much of Europe, and our input to the EU standards process has been inadequate or ineffective. Looking around my own house I see very few products that do not have some kind of internal overload protection, whether intentional or not.

Your point about instructions is interesting, that manufacturers may use them in ways to minimise their difficulties rather than to give exact compliant instructions to BS7671 installation only. This should receive some discussion at some point because I don't think that is the intention of the wording in BS7671 about instructions.

I fully understand the points you are making Graham, and it seems to have touched a nerve with everyone. However BS7671 is NOT the place to attempt to fix design difficulties with appliances, and we keep trying to do it, particularly with EVs at the moment!

I see where you are coming from with your element point, but this fault is really not very dangerous is it? If the element gets a fault in the centre, it will take twice the current and get 4 times the dissipation in the half section which will rapidly lead to melting of the element. This current will not give a dangerous volt drop on the Earth connection. You can calculate the worst-case fault position but it is very unlikely to raise the Earth voltage for very long to a dangerous potential (>50V). The RCD is thus protecting against an unlikely scenario, that is not dangerous, the CPD protects the high current cases. I have no objection to fitting RCDs, but is this really a case where BS7671 should take over, I think not?

Wall warts are a particularly bad case, but the two types are both pretty much intrinsically safe to the user, transformer ones by the primary winding (usually less than 1A fusing capacity) and the switch mode ones by component s or tracks blowing open circuit. The lack of fusing in other appliances is probably because the UK has much higher rated socket circuits than much of Europe, and our input to the EU standards process has been inadequate or ineffective. Looking around my own house I see very few products that do not have some kind of internal overload protection, whether intentional or not.

Your point about instructions is interesting, that manufacturers may use them in ways to minimise their difficulties rather than to give exact compliant instructions to BS7671 installation only. This should receive some discussion at some point because I don't think that is the intention of the wording in BS7671 about instructions.