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DanteJosh · 07-02-2018, 01:14 PM

Hi all,

I'm doing a conversion on a truck soon, and was wondering what gauge wire is ok for 12V appliances? I'm not using an inverter, so everything will be DC, for now. I have a kit for the connection between the alternator and the two cabin batteries that includes a Voltage Sensing Relay, and it comes with the proper gauges for that. I'm wiring everything into a panel: https://tinyurl.com/y762l3gs
So I guess two questions. What gauge for the 12VDC items and do I need a relay? If so, could anyone recommend a good relay?

Thanks so much,

Josh

cment · 07-02-2018, 01:20 PM

I know in marine applications I have always used a chart that uses length and Amps to determine wire size. Here is a new one from West Marine.

https://www.westmarine.com/WestAdvis...e-And-Ampacity

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Old-Biscuit · 07-02-2018, 01:29 PM

And another wire chart
https://www.engineeringtoolbox.com/a...uge-d_730.html

*Cment was posting as I was looking

Soppy · 07-02-2018, 03:52 PM

Using the chart cment posted will work good. Do not design for more than 3% voltage drop. If you are close to the max length , use the next larger wire. Try to keep the runs as short as possible.
A relay can be used for high current loads if the switch has to be located a long distance from the load.

cment · 07-02-2018, 04:57 PM

I know it might be over kill to some, but I would invest in marine grade wire (UL stamped prefable) if I were to do a build or add any system to my unit.

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