DaveInDenver
Middle Income Semi-Redneck
The reason you don't usually see fuses on communication lines is they are not getting power directly from a source.
There's a circuit driving the line that is inherently power limited, you're looking at a few tens of mW of power. It's basically impossible to burn up a signal wire from the circuitry driving it.
Indeed even the whole VBatt+ path on the shunt if the guts go haywire and fails internally it's likely going to burn up the device before the wire ever gets hot. There should be a fuse or otherwise inside it necessary to protect itself.
Sizing that wire and the fuse is completely driven by the wire itself and what's the source. It is a battery and not a communication driver.
The question you ask is "What would I want to happen if I left the end of this wire stripped and unterminated and it could touch something?"
It could spark or could short circuit melt the insulation or copper.
If that's OK then you don't need to do anything more, you're done.
This is part of the justification for not fusing very short cables, the ABYC (and others) suggest that a short jumper doesn't need a fuse. That's because if it overloads and melts open so what? The circuit opens, the cable may melt in half and you have two short pieces.
That's no worse than what you'd have with a fuse in the circuit. Something, somewhere, in a circuit with a power source will potentially always be live and you have to deal with it. So as long as you exercise reasonable care to bolt down, support and protect stuff then nothing can be harmed. You may want to consider ways to isolate a jumper in that case, e.g. a battery switch, a bigger fuse or breaker somewhere, to fix it.
But let's say your starter cable was to melt what would you do? Most manufacturers have no fuse and you're going to have to unbolt a terminal from the battery with half a live cable. It's a risk/cost analysis. It's very unlikely to happen. Or your winch. The majority of winch installations have no switch or fuse.
Another options is if the upstream stuff is current limited, say you're using a power supply (say a USB power) that can only source 1A or has it's own overload protection you might not need to do anything either.
A battery with a 150A breaker and a busbar offers none of this, though.
If that could start a fire, burn someone, damage something then you probably want to size the wire and fuse appropriately.
BTW, another option is since that is supposed to draw <1mA you could run a very small wire that will burn up so quick that it can't be a problem. That's the theory behind a fusible link, use a short length of wire contained in a fire resistant insulation that's two sizes smaller than the one you're protecting so you know what will burn up first. If you used 22AWG wire for that run you wouldn't need a fuse, it'd just burn up nearly instantly in a short, 40ms or something like that, with 150A available. I'd stick with a fused 16AWG, though.
There's a circuit driving the line that is inherently power limited, you're looking at a few tens of mW of power. It's basically impossible to burn up a signal wire from the circuitry driving it.
Indeed even the whole VBatt+ path on the shunt if the guts go haywire and fails internally it's likely going to burn up the device before the wire ever gets hot. There should be a fuse or otherwise inside it necessary to protect itself.
Sizing that wire and the fuse is completely driven by the wire itself and what's the source. It is a battery and not a communication driver.
The question you ask is "What would I want to happen if I left the end of this wire stripped and unterminated and it could touch something?"
It could spark or could short circuit melt the insulation or copper.
If that's OK then you don't need to do anything more, you're done.
This is part of the justification for not fusing very short cables, the ABYC (and others) suggest that a short jumper doesn't need a fuse. That's because if it overloads and melts open so what? The circuit opens, the cable may melt in half and you have two short pieces.
That's no worse than what you'd have with a fuse in the circuit. Something, somewhere, in a circuit with a power source will potentially always be live and you have to deal with it. So as long as you exercise reasonable care to bolt down, support and protect stuff then nothing can be harmed. You may want to consider ways to isolate a jumper in that case, e.g. a battery switch, a bigger fuse or breaker somewhere, to fix it.
But let's say your starter cable was to melt what would you do? Most manufacturers have no fuse and you're going to have to unbolt a terminal from the battery with half a live cable. It's a risk/cost analysis. It's very unlikely to happen. Or your winch. The majority of winch installations have no switch or fuse.
Another options is if the upstream stuff is current limited, say you're using a power supply (say a USB power) that can only source 1A or has it's own overload protection you might not need to do anything either.
A battery with a 150A breaker and a busbar offers none of this, though.
If that could start a fire, burn someone, damage something then you probably want to size the wire and fuse appropriately.
BTW, another option is since that is supposed to draw <1mA you could run a very small wire that will burn up so quick that it can't be a problem. That's the theory behind a fusible link, use a short length of wire contained in a fire resistant insulation that's two sizes smaller than the one you're protecting so you know what will burn up first. If you used 22AWG wire for that run you wouldn't need a fuse, it'd just burn up nearly instantly in a short, 40ms or something like that, with 150A available. I'd stick with a fused 16AWG, though.
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