The RV Forum Community

RVing message boards => Tech Talk => Topic started by: garyb1st on September 27, 2017, 03:14:40 PM

Title: Wire for Inverter
Post by: garyb1st on September 27, 2017, 03:14:40 PM
I have 50 feet of 10/3 SJTW wire.  I'm thinking of making a 30 to 40 foot extension cord and possibly using some of the wire to connect an inverter to the house batteries.  The inverter will be no more than 1,000 watts.  We only have two 12V batteries and will only use the inverter to power a computer and the television.   Depending on where I put the inverter, it will take maybe 10 - 15 feet of wire.  Is the 10/3 wire adequate for an inverter or should I go with heavier wire.
Title: Re: Wire for Inverter
Post by: sunfighter on September 27, 2017, 03:33:29 PM
If I'm reading this correctly, I don't think it'll work. my inverter is connected to my batteries with 2.0 cable and is only 4 feet from them. Everthing I have heard about inverter connections say's heavy cable/short runs are best. That said, I have never tried using lighter wire so maybe someone else who has can chime in.   
Title: Re: Wire for Inverter
Post by: Harry B on September 27, 2017, 05:21:52 PM
It will work for the 120vac output of the inverter and length is not critical there.
However for the DC input to the inverter you will need at least 4 ga. cable and as close as possible to the inverter so your length won't exceed 10ft.
Title: Re: Wire for Inverter
Post by: garyb1st on September 27, 2017, 06:02:00 PM
Thanks for the replies.  That was my understanding as well but I just wanted to double check.  Biggest issue for me is location of the inverter.   Since the batteries are located under a step in the stairwell, I will need at least 6 feet and then not for an ideal location. 
Title: Re: Wire for Inverter
Post by: AStravelers on September 27, 2017, 06:52:08 PM
Us a wire size calculator to determine the wire size you need:  http://circuitwizard.bluesea.com/ (http://circuitwizard.bluesea.com/)

For the wire length use the round trip length.  That is if the battery is 5' from the inverter, use 10' in the calculator. 
Title: Re: Wire for Inverter
Post by: Dorian on September 28, 2017, 11:08:49 AM
Harry's got the right idea.  Keep the inverter as close to the battery as possible, and then you can run a power bar with a 12ft cord wherever you need the outlets.
Title: Re: Wire for Inverter
Post by: Gary RV_Wizard on September 28, 2017, 12:45:24 PM
Moat people don't realize that a 1000W inverter can pull 90+ amp from the batteries, so it needs wire rated for that much amperage.
Title: Re: Wire for Inverter
Post by: AStravelers on September 28, 2017, 07:11:53 PM
Moat people don't realize that a 1000W inverter can pull 90+ amp from the batteries, so it needs wire rated for that much amperage.
That is why you need to use a wire size calculator to properly size the wire.  The important number is to limit the voltage loss to 2% or less for the round trip distance the wire must travel.  The distance the wire travels, due to the way it is routed can be a lot longer than what eye balling the distance. 
Title: Re: Wire for Inverter
Post by: touchracing on September 29, 2017, 07:08:16 AM
For what it's worth earlier this year I installed a 1000 watt Xantrex inverter in my travel trailer.  From my batteries to the inverter I have a total of 14 feet of 1/0 welding cable with a 120 amp re settable circuit breaker.  From the inverter to the transfer switch i used about 20 feet of 10/3 romex.  So far this setup has exceeded my expectations.