Black b40 fuse keeps tripping on Wylex fuse board, help.

[scotty74]

Please could someone give me some advice, i awoke to find no electricity on any power socket in my house, normally i will just reset the large middle trip switch, it wouldnt work, i have turned off all sockets in house and tried again but nothing, the only way i can get everything back on is to leave the far left switch tripped, its a b40 and i don't know what this means. is it dangerous to leave this like it is, i cannot see that it is connected to anything i have turned back on. Many thanks

 

[Taylortwocities]

It means that it is a 40amp breaker. That will be feeding something, somewhere that need a lot of current…only you can find that out.

It could be a feed to an outhouse/garage perhaps? Other suspects might be a cooker or a shower.

 

[JohnW2]

... normally i will just reset the large middle trip switch, it wouldnt work,

What is written on that trip switch? Does it have a test button?

Are you saying that the 'large middle trip switch' trips and you can only reset it if you turn off the B40 breaker?

Kind Regards, John

 

[scotty74]

Thanks guys i think its the shed as the shed has no power at all, but it does have its own power board in there and none of the switches are tripped, which does seem a bit weird, everything in the house including cooker are working without the 40b switch on, do you think i am safe just to leave this switch off?

 

[scotty74]

Yes john, exactly that, i can only reset main black switch when 40b is switched off, am i ok to leave this off if it only seems to be supplying my shed, which i don't use anyway? thanks x

 

[ban-all-sheds]

That will be OK.

The "large middle trip switch" is an RCD, and there's a fault somewhere in the shed supply or installation which is tripping it. Turning off the MCB removes the fault.

 

[JohnW2]

That will be OK. The "large middle trip switch" is an RCD, and there's a fault somewhere in the shed supply or installation which is tripping it. Turning off the MCB removes the fault.

... at least for the time being. If something in the shed is filling up with water, it might eventually evolve into a neutral-earth fault large enough to trip the (presumed) RCD, even if the (presumed single-pole) MCB is turned off. If that happens, the OP may have to disconnect the (apparently unwanted) circuit from the B40 MCB.

Kind Regards, John

 

[scotty74]

Thankyou John you have put my mind at rest, hubby is rubbish with anything diy so it wasn't worth phoning him lol. Wanted to make sure it was safe. Thanks again.

 

[securespark]

If you switch the shed's board OFF, does the RCD reset with the B40 breaker ON?

That will tell you if the fault is on the cable between the B40 breaker and the shed board or somewhere on the shed's circuits.

Are you sure there is nothing there you don't need?

Like power to a fridge or freezer or a pond pump?