VHF fused on pos & neg

[B27]

For crying out load....... how well do you think a 2.5mm wire will fare if it came into contact with one of the bow thruster cables, or windlass cables, or main starter cables ????

I didn't say it was likely, i put forward an explanation as to how the event is post #6 could be possible.

If you've got bare naked bow thruster connections and the like, maybe you need fuse in you anchor chain, tools etc?

Protecting things by fusing the negatives is a fairly poor way forwards, when what's needed is to protect all the live wires from contact.
Particularly any high current positives.

 

[PaulRainbow]

If you've got bare naked bow thruster connections and the like, maybe you need fuse in you anchor chain, tools etc?

The bow thruster cable was an example of something that would have a fuse fitted that would not be likely to blow if a 2.5mm negative cable came into contact with it. One doesn't need lots of bare positive connections, things go wrong, that's how accidents happen.

Protecting things by fusing the negatives is a fairly poor way forwards, when what's needed is to protect all the live wires from contact.
Particularly any high current positives.

I didn't suggest fusing negatives, did ? I simply posted a scenario where a negative wire can overheat without blowing a fuse.

Do you actually have anything useful to post ? Thought not.

 

[bedouin]

Fuses protect the leads as well as the device. I had a fuse on the positive VHF lead when I noticed smoke escaping from the lazarette. A quick check revealed that the unfused negative lead from the battery to the VHF was smoking along its length and the insulation was boiling. Now the negative lead is also fused and an on/off battery switch has been installed.

It is possible the -ve lead from the VHF was also carrying the negative current from another device. The VHF is probably not entirely isolated and may well be connected/earthed to another -ve point (e.g. a switch board, or even a data connection). A problem in another circuit could then lead to the VHF =ve wire carrying all the -ve current back to the battery.

But it would have to be something with a fairly high current draw - e.g. fridge - or perhaps the charging current from the alternator, although that sounds highly unlikely.

Was the VHF on and working normally at the time?

 

[PaulRainbow]

It is possible the -ve lead from the VHF was also carrying the negative current from another device. The VHF is probably not entirely isolated and may well be connected/earthed to another -ve point (e.g. a switch board, or even a data connection). A problem in another circuit could then lead to the VHF =ve wire carrying all the -ve current back to the battery.

But it would have to be something with a fairly high current draw - e.g. fridge - or perhaps the charging current from the alternator, although that sounds highly unlikely.

Was the VHF on and working normally at the time?

But the OP says "The wires and the fuse were the ones supplied with the Icom VHF set, which I connected directly to the battery."

 

[MADRIGAL]

It is possible the -ve lead from the VHF was also carrying the negative current from another device. The VHF is probably not entirely isolated and may well be connected/earthed to another -ve point (e.g. a switch board, or even a data connection). A problem in another circuit could then lead to the VHF =ve wire carrying all the -ve current back to the battery.

But it would have to be something with a fairly high current draw - e.g. fridge - or perhaps the charging current from the alternator, although that sounds highly unlikely.

Was the VHF on and working normally at the time?

Alas, no fridge or bow thruster on a Wayfarer! We only have nav. lights and the VHF. The whole episode was very weird, and my extra fuse may make no sense at all, but I thought of it when the OP said he also had one on his negative VHF lead.

 

[VicS]

Alas, no fridge or bow thruster on a Wayfarer! We only have nav. lights and the VHF. The whole episode was very weird, and my extra fuse may make no sense at all, but I thought of it when the OP said he also had one on his negative VHF lead.

I assume the fuse(s) in the original leads is/are close to the radio. ( mine is ) In which case they only protect the radio.

There should be a fuse(s), or circuit breaker, close to the supply to protect the wiring to the radio . Commonly this would be a fuse or cb in the main DC control panel.

 

[scurr]

both fuses and old wiring are now gone. Just re-ran new (which includes a new fuse on positive per manual spec). New motto, if in doubt - replace. I didn't like the connectors.

It is possible the -ve lead from the VHF was also carrying the negative current from another device. The VHF is probably not entirely isolated and may well be connected/earthed to another -ve point (e.g. a switch board, or even a data connection). A problem in another circuit could then lead to the VHF =ve wire carrying all the -ve current back to the battery.

But it would have to be something with a fairly high current draw - e.g. fridge - or perhaps the charging current from the alternator, although that sounds highly unlikely.

Was the VHF on and working normally at the time?

It was working ok.

 

[scurr]

both fuses and old wiring are now gone. Just re-ran new (which includes a new fuse on positive per manual spec). New motto, if in doubt - replace. I didn't like the connectors.

 

[scurr]

How was it failing?

It wasn't. I was asking if I was missing something on the why