Electrical installation. Diversity?
specify a suitable cable and circuit protective device.
any help is appreciated thank you
Answer:
I do this for a living "The first 10A of the rated current plus 30% of the remainder of the rated current plus 5A for an integral socket ". 10.2kW is 44Amps which becomes 25Amp loading after diversity. So a 2.5mm twin & earth cable and 25A MCB 'Type B' protective device should do it.
If your doing a city & guilds / National Certificate assigment, give me some credit, wink-nudge.
Oh and the guy below me has a very good answer, except that you can't fit 10mm cable into a 45A cooker switch. The max is 6mm. But take his word over mine, he has more experience than me behind an office desk.
Is this for real, you're talking about a 12/13kW spur there?
Running any thing that big on a domestic circuit needs special wiring. There are showers now that are 9-10kW, and you need to run a cable that will take that load from your consumer unit. Unless your cooker cable has been rated to take that high load, don't do it. If you do have suitable wiring, I suggest a circuit breaker rated to take a 10KW load, such as for a shower unit, should do. But check first with an electrician.
As mentioned before the 10.2kw equates to approx 45Amp @ single phase (44.34Amps to be precise taking power factor as unity)
Diversity is only applied when there is more than one circuit, the diversity is for the incoming power supply rather than the individual circuit.
Take for example your consumer unit, it will prob have a 100Amp or 80Amp Single phase incomer mains switch but if you add up the individual MCB's (fuses) in the board you will notice that they will exceed the size of the main incomer, this is when diversity is applied, you may have 2No 32Amp MCB's/RCBO's for the sockets, a 16Amp for the heating, 2No 6Amp for the lighting circuits, 50Amps for a cooker, 50Amps for a shower... etc...If these amounts are added they are well in excess of the main switch, the reason the main switch does not operate is due to diversity (not all circuits are taking maximum load)
If the cooker requires 10.2Kw (45Amps) to operate correctly then you should make sure that it gets the 45Amps required. I would install a 45Amp MCB as this shall cover the cooker and the socket. The wiring i would use would be 10mm Twin & Earth cable. You can wire this into a cooker connection unit (sometimes know as an elephants nose)
If you supply the cooker with a lower current value, the cooker shall not operate correctly and the protective device shall operate due to over current.
The information for the cooker is rating the power supply required for the cooker so do not install anything less than is asked for. If you install a 45Amp MCB do not use a smaller size of cable because if a fault occurs causing a fault current of 40Amps the protective device shall not operate and the wiring shall burn!
You do not apply diversity to a 10.2kw cooker. The reason for this is it is likely that all the rings oven and grill could be on on Christmas day for instance. Therefore you need a 10mm cable connected to a 45amp mcb. Depending on your earthing supplied by the DNO you might need a 100ma RCD.
You should complete C&G 2391 before you attempt to connect the cooker as you will require an electrical installation certificate to keep within the law.
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