Even if there was 10mm cable in on a 8.5wk shower. Is a 45 amp breaker not to high as it would not trip in time ?
Would a 40 amp not be suited better, 8500 kw divided by 240v is 35.4 amp or based on 230 v is 36.9 amp ?
Proteus BS5486 cartridge
- Thread starter diycooper
- Start date
Would a 40 amp not be suited better, 8500 kw divided by 240v is 35.4 amp or based on 230 v is 36.9 amp ?
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A 45A breaker (or even a 50A one) would 'trip in time' to give adequate protection to a 10mm² cable. That's how we work out what size cable is needed with a particular rating of breaker.
Kind Regards, John
Thanks John understood, but a 45amp breaker would be overkill for a 7.5 kw shower more suited to a 10.5 kw shower ?
Not really. It is the cable, not the shower, that determines how 'big' a breaker you can have.
Think about the sockets circuit(s) in your house. they will probably be on 32A breakers (which is chosen to be OK for the cable), but for much/most of the time, the loads on the circuit will probably be a very small fraction of that.
Kind Regards, John
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161QEB is the part number
16 for 16A and 1QEB for the range
32 for 32A and 1QEB for the range
I'd advise against replacing those MCBs. They are getting to the end of their usable life. My last flat had those in, came home to no lighting one day, assumed the MCB had tripped. Nope, the MCB had just failed with the dolly in the closed position.
Thanks for replying
Are you suggesting a consumer unit change ? You can buy them fuses still brand new ?
Where have you seen them new, they are now special order only and very expensive
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The problem with old breakers like that on eBay is you don’t know what kind of life they’ve had.
It could be next to unused or it could have been totally abused and be really weak. There’s no way to know and there’s no way to test them.
It could be next to unused or it could have been totally abused and be really weak. There’s no way to know and there’s no way to test them.
True, that one claims to be "new, but without box and with some storage-related marks". If the seller is being honest, it's probably OK, but one can never know for sure.
Kind Regards, John
I worry about whether you are competent to to this.
- You don't know the difference between a fuse and an MCB (and this is not pointless pedantry - your terminology betokens a great lack of awareness).
- You are replacing a 16A device with a 32A device, the 16A one has a model number 161 QEB and the 32A one is a 321 QEB, and you don't understand why.
What is the circuit? What investigations have you done to verify that you can safely uprate it to 32A?
Are you planning to apply for Building Regulations approval?
Same with all the breakers in the CU when you buy a house which is not brand new.
Speaking of "no way to test them" ...
It would be interesting to know how the MCBs (and, indeed, overcurrent function of RCBOs) had been 'tested'The linked eBay listing said:
Mind you, it's not as bad as the eBay listing I saw recently for fuses which had been "100% tested before despatch"!
Kind Regards, John
A new house doesn’t necessarily even mean new MCB’s! New builds are so price driven I don’t doubt there’s the odd MCB that was knocking around in the van in a lot of them to save the £2.50
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