Turning a temporary 12V cable into a fuse

simonfraser

simonfraser

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Supply to the paraffin hob and fridge has died
Not obvious to me what happened, I assume a fuse has blown, but cant locate it

So can rig up a temporary power cable, but don't have any fuses on board :(

Could weaken the cable by cutting out some of the copper, how many strands to leave in ??

Guess would be good if it blew at about 15 A ....
 
simonfraser said:
Supply to the paraffin hob and fridge has died
Not obvious to me what happened, I assume a fuse has blown, but cant locate it

So can rig up a temporary power cable, but don't have any fuses on board :(

Could weaken the cable by cutting out some of the copper, how many strands to leave in ??

Guess would be good if it blew at about 15 A ....
Click to expand...

Enough to have the same cross sectional area as 15amp fuse wire which appears to be 0.020" diameter. I assume you have a micrometer available
 
Probably not so. Copper has a lower resistance than fuse wire, it would seem. This from Wiki;

The fuse element is made of zinc, copper, silver, aluminum,[citation needed] or alloys to provide stable and predictable characteristics.[4][5] The fuse ideally would carry its rated current indefinitely, and melt quickly on a small excess.

So the lower resistance would mean less heat generated for a given current and so less protection.

I await correction:cool:
 
Champagne Murphy said:
Probably not so. Copper has a lower resistance than fuse wire, it would seem. This from Wiki;

The fuse element is made of zinc, copper, silver, aluminum,[citation needed] or alloys to provide stable and predictable characteristics.[4][5] The fuse ideally would carry its rated current indefinitely, and melt quickly on a small excess.

So the lower resistance would mean less heat generated for a given current and so less protection.

I await correction:cool:
Click to expand...

Tinned copper! 25swg ( which is 20thou as I measured)

https://www.tlc-direct.co.uk/Produc...MIqIH76JLS1QIVL7vtCh0VHAXxEAQYAiABEgKKPPD_BwE

simonfraser said:
Cos i dont ! :D
Click to expand...
Most people have one of those digital verniers from Lidl or Aldi!
 
Surely you have something with a mains plug?
Usually find a 13A fuse in those?

Fusewire is some alloy where the resistance rises quickly as it heats up, so once it starts heating, it heats quicker and blows. Copper won't work the same!
 
I know I am a bit rough a times with electrics but I would just take a wire from 12v supply to fridge input without a fuse.
This may make the fridge work. It may also carry a lot of current if the fridge exhibits a short circuit. In which case depending on the thickness of wire you will observe heating of the wire. Or you may observe a high current on a ships amp meter or fit your multimeter on 10 amp range in the temporary circuit.
If nothing happens then perhaps you have a problem with the negative return wire which can also be duplicated for test.
Fuses don't often "blow" although they often fail from old age and vibration or the connections to the fuse fail from corrosion etc. So get the multimeter or test lamp out and track down where your 12v is getting lost. good luck olewill
 
Where are you in the world that has none of:

- yacht chandler
- car parts shop
- petrol station
- diy / iron monger
- electical shop
- any mains electrical equipment

All of which will have fuses available, since you aren't fussed about size/format.

Ordinarily I might take William's view, but not if I believed I had already blown a fuse, then I wouldn't be so keen to bypass it.
 
simonfraser said:
Supply to the paraffin hob and fridge has died
Not obvious to me what happened, I assume a fuse has blown, but cant locate it

So can rig up a temporary power cable, but don't have any fuses on board :(

Could weaken the cable by cutting out some of the copper, how many strands to leave in ??

Guess would be good if it blew at about 15 A ....
Click to expand...

Wire it to one of the other circuits? Perhaps cabin lighting - shouldn't be the end of the world if (when) you blow that fuse too..
 
If you thin down a copper wire it will have a greatly increased resistance, causing voltage drop in the circuit, so the equipment is quite likely to fail to work anyway. As others have said, the wire will not melt in the manner of a fuse so there is no guarantee of any protection. I have had a wire in a car melt all its insulation due to a short circuit and the only solution was to disconnect the battery til I had isolated the circuit. Why the fuse didn't blow, I will never know for sure!

Rob.
 
penberth3 said:
I think we have a winner! Sometimes it's the simplest ideas that do the trick.
Click to expand...

doh, that would have worked !

i checked for a spark / major voltage drop when initially connected, which was not present so enjoyed the cold wine and warm dinner as my paraffin hob requires current.
rummaged in the spares box, eventually found a 25A spade fuse, but no holder.
have a gas solder iron, so made up a temp fuse.

not bought a micrometer yet .......
 
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