What fuse wire should I use

[ryetee]

I've just moved into my flat and the boiler didn't work. It turned out that the main fuse had blown.

My problem is what fuse wire should I use. The actual fuse is 20amp (old yellow dot) but it had a sticker over saying boiler and vent (fan) so I'm guessing that 20 amp is not correct. The blown fuse looked like it was 5 amp. I've bought some fuse wire which comes in 5amp, 15 amp and 30 amp.

Question is which should I use? At the moment I've gone for 15amp.

Dave

 

[JohnW2]

I've just moved into my flat and the boiler didn't work. It turned out that the main fuse had blown. My problem is what fuse wire should I use. The actual fuse is 20amp (old yellow dot) but it had a sticker over saying boiler and vent (fan) so I'm guessing that 20 amp is not correct. The blown fuse looked like it was 5 amp. I've bought some fuse wire which comes in 5amp, 15 amp and 30 amp. Question is which should I use? At the moment I've gone for 15amp.

Your real problem probably relates to the reason (whatever it was) that the fuse blew. If you haven't discovered, and rectified, the cause of that happening, the chances are that any new fuse wire you put in will immediately blow again.

The technical answer to your question is that the appropriate size of fuse (wire) depends on the size of the cable in the circuit (since the fuse is there to protect the cable). However, if that fuse really does only serve the boiler and fan, then 5A fuse wire ought to be more than adequate.

Kind Regards, John

 

[ryetee]

I've just moved into my flat and the boiler didn't work. It turned out that the main fuse had blown. My problem is what fuse wire should I use. The actual fuse is 20amp (old yellow dot) but it had a sticker over saying boiler and vent (fan) so I'm guessing that 20 amp is not correct. The blown fuse looked like it was 5 amp. I've bought some fuse wire which comes in 5amp, 15 amp and 30 amp. Question is which should I use? At the moment I've gone for 15amp.

Your real problem probably relates to the reason (whatever it was) that the fuse blew. If you haven't discovered, and rectified, the cause of that happening, the chances are that any new fuse wire you put in will immediately blow again.

The technical answer to your question is that the appropriate size of fuse (wire) depends on the size of the cable in the circuit (since the fuse is there to protect the cable). However, if that fuse really does only serve the boiler and fan, then 5A fuse wire ought to be more than adequate.

Kind Regards, John

Thanks John, I'll change the 15a for 5a and if that blows call in some profession help!
Just one more thing - why would they (presumably previous electrician) have a fuse with just the boiler and fan on? Is that standard (UK) practice?

 

[JohnW2]

Thanks John, I'll change the 15a for 5a and if that blows call in some profession help! Just one more thing - why would they (presumably previous electrician) have a fuse with just the boiler and fan on? Is that standard (UK) practice?

You're welcome. It's not that unusual - the arrangement of circuits varies widely. It may be that it was just more convenient to do it that way for one reason or another. Having said that, how certain are you that it does only supply the boiler and fan? If it actually supplies a lot more that just that, you could find that the 5A fuse is not big enough!

Kind Regards, John

 

[PrenticeBoyofDerry]

Just one more thing - why would they (presumably previous electrician) have a fuse with just the boiler and fan on? Is that standard (UK) practice?

As you have rewireable fuse, that would suggest the installation is dated, so the original set-up may not have been as the current one is!
It could have well been a circuit that was originally for a cylinder immersion heater and that has now been removed and the boiler fitted to it, and at some time a fan was connected to the circuit as it was convenient to do so.
But as previously mentioned, it is important to find out why the fuse has blown!

 

[Robin0577]

Just one more thing - why would they (presumably previous electrician) have a fuse with just the boiler and fan on? Is that standard (UK) practice?

Whilst it might not be done that way if starting from scratch, it's very common practice to re-use an old 15/20 amp electric water heater circuit to supply a boiler when the boiler is replacement source of hot water.

 

[ryetee]

Thanks John, I'll change the 15a for 5a and if that blows call in some profession help! Just one more thing - why would they (presumably previous electrician) have a fuse with just the boiler and fan on? Is that standard (UK) practice?

You're welcome. It's not that unusual - the arrangement of circuits varies widely. It may be that it was just more convenient to do it that way for one reason or another. Having said that, how certain are you that it does only supply the boiler and fan? If it actually supplies a lot more that just that, you could find that the 5A fuse is not big enough!

Kind Regards, John

Only going by the fact it had a small sticker over the 20Amp sign that said boiler and vent! It's a small flat and it was only that and the vent that wasn't working. I currently have 15A fuse and boiler works (vent/fan still doesn't).

 

[ryetee]

Just one more thing - why would they (presumably previous electrician) have a fuse with just the boiler and fan on? Is that standard (UK) practice?

As you have rewireable fuse, that would suggest the installation is dated, so the original set-up may not have been as the current one is!
It could have well been a circuit that was originally for a cylinder immersion heater and that has now been removed and the boiler fitted to it, and at some time a fan was connected to the circuit as it was convenient to do so.
But as previously mentioned, it is important to find out why the fuse has blown!

Good thinking.
PLace has been empty for a year so not sure why it blew b4 but I'll keep and eye on it.

 

[JohnW2]

Only going by the fact it had a small sticker over the 20Amp sign that said boiler and vent! It's a small flat and it was only that and the vent that wasn't working.

Fair enough. If they are the only things not working, that's highly suggestive that those are all that the fuse/circuit supplies.

I currently have 15A fuse and boiler works (vent/fan still doesn't).

I suppose it's possible that the vent/fan is just dead? However, are you sure there is not a separate switch or 'fused connection unit' for it somewhere which has been switched off (or fuse blown, if an FCU)? Are you sure that the vent/fan is meant to be on all the time and is not controlled by some sort of sensor?

Kind Regards, John