Optimistic Paranoid
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Wire Sizes and Fusing:
There is a maximum amount of current that each size wire can carry safely before suffering either long term, or in some cases RAPID deterioration.
The technical term for this is its AMPACITY, which is a made-up term from the two words Ampere Capacity.
In addition to wire size, it is also partially dependent on the temperature rating of the insulation on the wire. Wire with insulation rated for 90 degrees Celsius has a higher ampacity rating than the same size wire with insulation rated for 60 degrees Celsius does. Bundling a bunch of wires together calls for derating the ampacity, because the wires in the center of the bundle can’t shed heat like they could if they were run singly.
Anyway here’s a simple table of fuse sizes matched to wire gauge size that’s close enough for government work, as they say.
For 14 gauge wire, it’s 15 amps
For 12 gauge wire it’s 20 amps
For 10 gauge wire it’s 30 amps
For 8 gauge wire it’s 50 amps
For 6 gauge wire it’s 80 amps
For 4 gauge wire it’s 125 amps
For 2 gauge wire it’s 200 amps
For 1 gauge wire, it’s 250 amps
For 1/0 gauge wire it’s 325 amps
For 2/0 gauge wire it’s 400 amps
You can ALWAYS put a smaller fuse on a wire safely. For instance, If I were installing a fuse block for my house circuits, and it was rated for a maximum of 100 amps, I would run 4 gauge wire(125 amps) from the battery to the fuse block, and fuse it close to the battery with a 100 amp fuse.
There is a maximum amount of current that each size wire can carry safely before suffering either long term, or in some cases RAPID deterioration.
The technical term for this is its AMPACITY, which is a made-up term from the two words Ampere Capacity.
In addition to wire size, it is also partially dependent on the temperature rating of the insulation on the wire. Wire with insulation rated for 90 degrees Celsius has a higher ampacity rating than the same size wire with insulation rated for 60 degrees Celsius does. Bundling a bunch of wires together calls for derating the ampacity, because the wires in the center of the bundle can’t shed heat like they could if they were run singly.
Anyway here’s a simple table of fuse sizes matched to wire gauge size that’s close enough for government work, as they say.
For 14 gauge wire, it’s 15 amps
For 12 gauge wire it’s 20 amps
For 10 gauge wire it’s 30 amps
For 8 gauge wire it’s 50 amps
For 6 gauge wire it’s 80 amps
For 4 gauge wire it’s 125 amps
For 2 gauge wire it’s 200 amps
For 1 gauge wire, it’s 250 amps
For 1/0 gauge wire it’s 325 amps
For 2/0 gauge wire it’s 400 amps
You can ALWAYS put a smaller fuse on a wire safely. For instance, If I were installing a fuse block for my house circuits, and it was rated for a maximum of 100 amps, I would run 4 gauge wire(125 amps) from the battery to the fuse block, and fuse it close to the battery with a 100 amp fuse.