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Old 07-07-2016, 08:10 PM   #1
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GA equivalent for paralleled cables?

If two cables are paralleled does the gauge double, quadruple? Two 4ga cables equals __ga?
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Old 07-07-2016, 09:19 PM   #2
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I can't find my trusty Ugly's Reference book, but 2/0 wire would carry the load of (2) 4 gauge leads if memory serves. It would be better than parallel runs, too. We overbuilt electrical equipment deliberately so I tend to go big.
It doesn't hurt to have a little overload insurance and less voltage drop.

Check with a marine electrician before buying anything.
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Old 07-07-2016, 10:29 PM   #3
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The simple answer is doubles the current capacity... However circuit breakers protect the wire so if you choose to run 2 wires to increase ampacity each wire should have the appropriate sized circuit breaker or fuse....
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Old 07-07-2016, 10:33 PM   #4
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If a 4 gauge for your given length of wire run has an acceptable voltage drop at 60 amps, then two paralleled conductors would work for 120 amps.

If you want to get a AWG equiv, take the circular mils of your cable, doubble it since you have two parallel conductors and find a cable size that has the same approx circular mills.
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Old 07-09-2016, 12:40 AM   #5
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#4 awg. Is 41740 cm
#1 awg. Is 83690 cm
So #1 is approx. Equal
There are some caveats. The two conductors mut be the same wire and the same length
Or uneven load splitting may occur.

May not be a problem but it could be goofing up V drop calc. And if running close to
capacity extra heating of one conductor if uneven split occurs.
Should work as long as details are paid attention to.
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Old 07-09-2016, 07:24 AM   #6
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My Victron inverter/charger's (3000w) installation guide called for two identical 12v positive cables from the battery bank. Only one fuse was specified.

Since then I have used the dual cable technique to add additional capacity to reduce the voltage drop between my battery bank and the positive and negative bus bars. The original cables were sufficient for safety. I have not put in separate fuses.
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Old 07-09-2016, 05:31 PM   #7
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Quote:
Originally Posted by Bay Pelican View Post
My Victron inverter/charger's (3000w) installation guide called for two identical 12v positive cables from the battery bank. Only one fuse was specified.

Since then I have used the dual cable technique to add additional capacity to reduce the voltage drop between my battery bank and the positive and negative bus bars. The original cables were sufficient for safety. I have not put in separate fuses.
Either have I.
My Victron inverter has twin 3/0 supplying it. (About 20 ft run IIRC) and it has a single fuse. Based on the run length you can have cables that exceed the fusing requirements for the inverter. Yeh I know the fuse is theoretically for the cable but this changes when you go to very large cable just for V drop.
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Old 07-09-2016, 06:28 PM   #8
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The way I understand the ABYC standards for OCP is that any wire directly connected to a battery with the exception of the starter motor must have an OCP device with in 72 inches of the battery. If the length of conductor is less than 72 inches I think that there is an exception.... I suspect that is for interconnection of batteries to make a battery bank. With the amount of energy available I would always opt to protect the wires from overheating.
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Old 07-09-2016, 08:10 PM   #9
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ABYC requires over current protection within 7 inches of the source of power unless the conductor is in a conduit or sheath. In that case you may extend it to 70 inches.
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Old 07-12-2016, 05:27 AM   #10
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Folks looking at fuses should consider "Class T" fuses.


Not all fuses work as well with high amperage .
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