fused spur blowing fuses

[robbie77]

Hello,
I have a fused spur that I'm trying to power the boiler with a 3 amp fuse. It keeps blowing fuses so I checked the wiring to at the spur and replaced the switched spur. It still blowing. Its spurred from upstairs ring so I isolated and tested the wires with a muli meter. The second time I did this the fuse blew when I just connected my multumeter to check volts between neutral and earth. Any ideas on what could cause this? Its ok with a 13amp fuse but there is obviously something wrong so will not use until sorted.


Thanks......

 

[thevenin]

Could be the ch pump blowing the fuse.Try disconnecting the pump then replace the fuse.
Regards,T

 

[flyingsparks]

Its something to do with the boiler and its controls. Nothing to do with the wiring which feeds the spur. Have you just done some work to the central heating or boiler, or has it suddenly just started doing this?

 

[chivers67]

When you say the fuse blew when you tested Earth to Neutral do you mean the actual three amp fuse in the FCU blew or the board fuse tripped?

 

[robbie77]

THanks for the replies. I mean the 3amp fuse in the spur keeps blowing. I have disconnected the wires from the spur to the central heating and tested with multimeter which blew it so I guess it must be the fuse wiring I think ill double check this. Any other tests I can try?

Thanks again

 

[robbie77]

I have tested the spur connections again and get 240v off the neutral and live and live and earth. No fuse blowing so I made a mistake somewhere testing.
Next plan to test the fuse spur connected to just the boiler and go from there.

 

[chivers67]

Looks likely to be the boiler issue as flying sparks suggested

(I thought perhaps you were tripping an RCD when you mentioned testing the neutral and earth)

 

[robbie77]

Oh ye wise heads. I started testing systematicaly and eventualy found it was the programmer. I have s plan plus and had both the hw on and ch on to smae terminal (6) this was causing the problem so I need to have a look at that. Got a wiring diagram somewhere!

Cheers guys.

 

[londonboy]

Don't use a 13amp fuse on a boiler! It can fry the PCB ... I know