I've recently had my consumer unit changed and I've only just noticed that my 10.5kW shower is now on a 40A MCB whereas it was previously on a 45A MCB.
Even with my grade C in A Level physics I can work out that a 10.5 KW shower pulls a tad more than 45 Amps. But when I spoke with the sparky who installed the new consumer unit, he argued that a 40A MCB is fine because it wouldn't trip under overload conditions unless it was pulling around 80A.
I'm not particularly worried (new MCBs are inexpensive enough) but it seems a bit daft to me to use an underrated MCB.
Even with my grade C in A Level physics I can work out that a 10.5 KW shower pulls a tad more than 45 Amps. But when I spoke with the sparky who installed the new consumer unit, he argued that a 40A MCB is fine because it wouldn't trip under overload conditions unless it was pulling around 80A.
I'm not particularly worried (new MCBs are inexpensive enough) but it seems a bit daft to me to use an underrated MCB.