Discuss reg to say 2 different size cables cant be used on one circuit if rcbo rated to lower cable? in the UK Electrical Forum area at ElectriciansForums.net
No there isn't a reg requiring consistent cable throughout a circuit. (In fact 433.3 mentions the scenario of a reduction in CCC.)Came across a cooker circuit with 10mm and 40A rcbo. Last leg was 6mm. Isolator to outlet. I downgraded to rcbo to 32A to accommodate the 6mm. Does the cable have to be the same throughout? If so what is the reg for this please.
Total wattage 8215w. No socket at isolation switch. So with diversity 32A works.Not sure if theres a reg on it but it's fine to do that on a radial circuit as long as the protective device is the correct rating for the smaller cable, as you've done. What's the wattage of the oven? The cable might need to be changed if it needs to be on a 40 amp.
Thanks Tim.No there isn't a reg requiring consistent cable throughout a circuit. (In fact 433.3 mentions the scenario of a reduction in CCC.)
If the 6 sq mm leg was clipped direct (when it can carry 47 amps before any further de-rating) it might have complied.
Basically 433.1.1 needs to be met for the whole circuit unless over-current protection can be legitimately omitted (see sections 433.2, 433.3 )
Came across a cooker circuit with 10mm and 40A rcbo. Last leg was 6mm. Isolator to outlet. I downgraded to rcbo to 32A to accommodate the 6mm. Does the cable have to be the same throughout? If so what is the reg for this please.
The cable might need to be changed if it needs to be on a 40 amp.
In fairly short supply 20 years ago, and I fear close to extinction now.so always us your common sense."
Reply to reg to say 2 different size cables cant be used on one circuit if rcbo rated to lower cable? in the UK Electrical Forum area at ElectriciansForums.net
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