Quick Electrical Help - power inverter

[garrett]

I'm going to be getting a power inverter soon and I need some quick help with how to wire it up.

For example, a 300 watt one. The max current through the wires to the inverter would be 25 amps, correct? (300 W/12 V)

What gauge wire do I need to use that will handle 25 amps?

I found many charts similar to this one: http://www.cablesandconnectors.com/wiregauge.html

but I don't know what the difference between "Maximum amps for chassis wiring" and "Maximum amps for power transmission"

So would I want to use 14 gauge or 6 gauge?

TIA

EDIT: I should add that I would probably never use the full 300 watts, but I still want to know the difference between those 2 columns so I know what gauge to use for a certain number of amps.

[Cebby]

Try this one.

http://whistlergroup.com/faq-inverters-answers.asp

6 gauge is what you should probably use according to the chart, but it depends on the length of the run. You want a fuse, not the wire to be the weak link.

[4runnerchevy]

25 amps, use #8, it gives use a little room. Make sure you use the same for positive and neg...

[glenyoshida]

You want to look at the chassis not the transmission rating.

There's one more variable you need to figure on, distance. The longer the distance the bigger the wire you need. You probably won't be running it much more than 12 feet from the battery terminal to your inverter. If you are buying a 300 watt inverter it's likely the max rating and not the continuous rating. The continuous is probably more like 200 watts. So guessing the above is the case you could run 14AWG and without any problems. Like 4runnerchevy said use the same gauge wire for your ground although know you do not have to run it all the way to the battery. You will likely find that you create less of a problem (with alternator whine noise coming through your laptop, radio, or CB) if you get your ground from the chassis near your inverter or at a point near the center of the vehicle.

If you are going to go through the trouble of running the power wire through the firewall, fusing it, and terminating it I'd suggest you buy a bigger wire in case you outgrow your 300 watt inverter or want to add something else later. The smaller the number the bigger the wire. So 8 AWG is a much bigger wire than a 14 AWG. If you buy an amplifier kit on ebay you can get an 8 gauge setup with a fuseblock, ring connectors ground, and probably a turn on wire for about $20 shipped. It's also going to be fine braid strand in a flexible insulator that will be much better quality than what you typically find at a local hardware store.

BTW make sure you make your cable going through the grommet dip or seal it with silicone or water will be directed into your cab.

[garrett]

cool, thanks for the help guys.

and glenyoshida, great tip on the wiring kits on ebay! i'll have to order one whenever i buy an inverter.