Hi I've had the boiler removed and have a spare MCB, have a 10.5kw shower I'd like to put in its place. Any idea which MCB would be a straight swap? Cheers T
You need a new consumer unit If you look at the shower instruction manual it will state a 30mA RCD, you have a 100mA RCD in the picture Also the RCD is an AC type RCD, these are no longer recommended for most circuits (Amendment 2 BS7671), as the RCD does the rest of the house there may be an issue with DC issues on other circuits. See RCD info I add on EICR's below Older AC type RCD's are prone to being blinded by dc leakage from other items plugged in to the property. In other words this RCD may fail to operate when other electronic items are plugged in which leak DC in to the mains. Regulation 531.3. 3 of BS 7671:2018+A2:2022 states that the appropriate RCD shall be selected according to the presence of DC components and AC frequencies. Further, Type AC RCDs shall only be used to serve fixed equipment, where it is known that the load current contains no DC components.
You might get a MCB through EBay for around fifty quid, if someone just happens to have put one up for sale. In all honesty, you will be better off putting your fifty quid towards having the consumer unit replaced, because as @baldelectrician.com pointed out you need a lower rated RCD as well.
@Carid As above, £50 for an extra MCB (not guaranteed fully functional), £50-80 for an RCCB (not guaranteed fully functional), £100 labour ... A new 4 circuit CU, with expansion room plus changeover will not be much more!
We do EICR's I always now recommend repalcement on an EICR for existing RCD's that are type A. It's really a cover my back thing as it's better to be save than sorry With the abundance of electronic things in properties now I don't know if an exisitng type AC RCD will be affected adversely but I do recommend chaging to clients- it is up to the client if they accept or ignore my advice but the buck is passed to them in the instance they decide not to.