What could be causing my boiler fuse to blow.
Discussion
What could be causing the fused spur to my boiler to keep blowing? I mean as soon as put a replacement in 
I’m in the process of having a new bathroom fitted which means 2 things, could this have caused it somehow? Secondly, I haven’t required hot water for 10 days, so it might have been like it for a while?
I’m in the process of having a new bathroom fitted which means 2 things, could this have caused it somehow? Secondly, I haven’t required hot water for 10 days, so it might have been like it for a while?
This sort of situation is what a Megger is made for.
Disconnect the cable from the DB and the boiler connection, and insulation test the cable, L1 -N, L1-E, N-E.
Then put it on resistance reading and carry out the same, to see what the passive resistances are.
If the bathroom work has interfered with the cable, then there's your fault.
It may mean digging the cable out as someone has inadvertently nicked it and water has penetrated.
Replace the cable, don't bodge it with sealant or tape..
Or, as they're loved on here, put in a JB with wago connectors.
Retest.
Then if the cable is good, investigate the supply side - with the DB isolated. Any small creature or moisture damage to the affected CPD?
Also what is the type of circuit protective device; is it an actual cartridge fuse? Is it a BS1363 plug and socket?
If that's all good, and the cable is fine, then that points to the boiler PCB. They can track down to earth for all sorts of reasons, especially if you keep whacking new fuses in!
Oh, and RNP has made some good points ref. the HW/CH marshalling box and circuits, separate and test these.
Disconnect the cable from the DB and the boiler connection, and insulation test the cable, L1 -N, L1-E, N-E.
Then put it on resistance reading and carry out the same, to see what the passive resistances are.
If the bathroom work has interfered with the cable, then there's your fault.
It may mean digging the cable out as someone has inadvertently nicked it and water has penetrated.
Replace the cable, don't bodge it with sealant or tape..
Or, as they're loved on here, put in a JB with wago connectors.
Retest.
Then if the cable is good, investigate the supply side - with the DB isolated. Any small creature or moisture damage to the affected CPD?
Also what is the type of circuit protective device; is it an actual cartridge fuse? Is it a BS1363 plug and socket?
If that's all good, and the cable is fine, then that points to the boiler PCB. They can track down to earth for all sorts of reasons, especially if you keep whacking new fuses in!
Oh, and RNP has made some good points ref. the HW/CH marshalling box and circuits, separate and test these.
Edited by Regbuser on Wednesday 16th July 18:51
You could consider disconnecting the power wiring at the boiler and either terminating it safely in a choc bloc or similar or wiring in a simple light bulb perhaps,
If the fuse still blows the fault is in the wiring in the wall not the boiler.
Take photos of the wiring before disconnecting anything so you can put it back together correctly.
OTOH, if have to ask, pay a sparks to look at it!
You could check the fuses you are using are the correct rating!
If the fuse still blows the fault is in the wiring in the wall not the boiler.
Take photos of the wiring before disconnecting anything so you can put it back together correctly.
OTOH, if have to ask, pay a sparks to look at it!
You could check the fuses you are using are the correct rating!
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