02-26-2008
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Telstar 28
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Join Date: Mar 2006
Location: New England
Posts: 43,315
Rep Power: 11
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This is only true if you've wired the circuit with wire of a heavier gauge than necessary for the load and run length. Generally, I prefer to oversize the wiring on my boat by a bit...going up a size in wire gauge, since oversized wiring is generally not the problem undersized wiring is, and it reduces the voltage drop at the terminal end as a bonus.
Quote:
Originally Posted by xtatico1404
One of the branch circuits has a Rule 360 bilge pump, which draws 2.1 amps and will probably be wired with a #18 gauge (not taking into account voltage drop, wire length, bundling or any other de-rating issue). Outside of engine space, a #18 will give you 20A according to industry tables. The fuse or the breaker is a 2.5 Amp. The reason behind it being fused to the load on the branch circuit is that if you have a short circuit of say 18 Amps, and your breaker/fuse was 20Amp, the breaker will not protect the load. However, if you fuse to the load, with a 2.5Amp fuse, you will be protecting BOTH the load and the wire.
So, in branch circuits, you size the fuse/breaker to the load.
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Sailingdog
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Telstar 28
New England
You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.
—Cpt. Mal Reynolds, Serenity (edited)
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