inverter dc cable size

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URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=97365
Printed Date: May 05, 2024 at 7:05 AM

Topic: inverter dc cable size

Posted By: gt40mech
Subject: inverter dc cable size
Date Posted: September 23, 2007 at 3:33 PM

I am installing 2 Xantrex X-power 1200 inverters in a custom Sprinter van. I've never done anything like this before and could use some advice from experienced installers.

The installation instructions say to use 2ga wire for the + cable and 8ga for the - cable.

Two questions:

1. Why the big difference in wire size for the pos and neg DC cables?

2. Space for routing the cables is really tight. Would running 4ga + cables make much of a difference in the inverters operation? One of the inverters will be powering about 750 watts and the other only about 100 watts. I could splt the loads more evenly if that would help.

Thanks,

Inverter newbie

Replies:

Posted By: i am an idiot
Date Posted: September 23, 2007 at 4:22 PM

The only reason I could see for them telling you to use smaller ground wire is if they are depending on the chassis of the inverter help by grounding it to the chassis of the vehicle. I would not count on the mounting screws for a ground. If there is enough room for a 2 Ga. ground I would use it. Do the inverters have fuses mounted on them? If so how many and what size are they? Where size = current.

Posted By: gt40mech
Date Posted: September 23, 2007 at 6:16 PM

No the inverters do not have integral fuses. The instructions say to use a 150 amp fuse on the power cable to the inverter. A 400 watt inverter I have on hand has a 35 amp fuse. That would put the 1000 watt inverter at about 90(?) amps. The only reason I can see for a 150 amp fuse is to protect the pos. power cable and the vehicle battery. The inverter has built in thermal and overload protection. I really need to reduce the size of the positive cables.

Thanks

Posted By: i am an idiot
Date Posted: September 23, 2007 at 9:08 PM

A 4 Ga. wire should be fused at 150 amps. Since you will not be running either of them close to the rated 1200 watts, I would have to say you will be safe with the 4 Ga. wire.

Posted By: fakepete
Date Posted: September 23, 2007 at 9:25 PM

If the total load is only 850 watts, do you really need to use both inverters?

Posted By: gt40mech
Date Posted: September 24, 2007 at 5:33 AM

two reasons for 2 inverters:

the customer wants the option of powering a small fridge or microwave and these converters were the closest I could find price and power wise that had a remote on-off switch. Space is REALLY tight with no room for the large relays needed for remote switching.

Posted By: CapSS92
Date Posted: September 25, 2007 at 4:36 AM

I agree with the 4ga. You should be ok.

Posted By: throwing_copper
Date Posted: September 27, 2007 at 1:33 PM

What is the pos cable length? If 20+ feet , one guage larger is wise.