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Topic: Lighting Wiring capacity (Read 927 times) previous topic - next topic

Lighting Wiring capacity

I bought a small inverter to power some of the a/v equipment when boondocking. . It's rated at 400 watts but says it should be connected directly to the battery for loads over 150w.

There are 12v sources in the overhead by the tv bug I have ok idea what their capacity might be?

Thanks
Randy (N4TDT) and Karen Crete
Sarasota, Florida
SOLD:  2000 U270 34' WTFE Build 5756 "Ole Red"

Re: Lighting Wiring capacity

Reply #1 –
Watts = volts x amps, so amps = watts/volts = 400/12 = 33.3 amps. 10 ga. is good for up to 30A, while 8 ga. is good for 40A.

Remember that if an appliance draws 1A @120 volts the inverter will have to draw 10 amps @ 12 volts, and that's without taking efficiency into account. My suggestion would be to mount the inverter as close to the batteries as possible and use the heaviest wire you can, meaning that you should use no less than 8 ga. from the batteries to the inverter. 400 W is 3.3 amps, so even 14 ga. household wire would be fine for the ac side.

Re: Lighting Wiring capacity

Reply #2 –
Average 40 inch led tv, 70 watts, average directv receiver 30 watts. 100 watts at 12 volts, 8 amps.
Automotive Wire & Wiring Guide from TESSCO - TESSCO.com
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Lighting Wiring capacity

Reply #3 –
Randy,
Your overhead 120v electric comes from one circuit on the secondary panel (also powered by the inverter).  It also goes to other places.  Find where it branches to the front overhead behind the refrgerator or under the kitchen and split it there.  Connect that end of the branch to a 120v circuit breaker and then to the small inverter.  12v coming to the inverter can come from the 12v lines to the big inverter or anywhere else it is convenient.  The +12v side should be fused close to the source.

This puts all of your front end on an inverter powered circuit.  Add switched outlets overhead so that you can turn off loads not being used.

A Second House Battery Bank, Solar Panels, 2 New Inverters

It is 3-300 watt panels



And a good DC wire size calculator.
Bos'ns' Corner - Wire Size Calculator


Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Lighting Wiring capacity

Reply #4 –
Quote from: Roger & Susan in Home2 –
Randy,
Your overhead 120v electric comes from one circuit on the secondary panel (also powered by the inverter).  It also goes to other places.  Find where it branches to the front overhead behind the refrgerator or under the kitchen and split it there.  Connect that end of the branch to a 120v circuit breaker and then to the small inverter.  12v coming to the inverter can come from the 12v lines to the big inverter or anywhere else it is convenient.  The +12v side should be fused close to the source.

This puts all of your front end on an inverter powered circuit.  Add switched outlets overhead so that you can turn off loads not being used.

Think I did the same thing as Roger, took fwd 120 outlet from inverter panel and ran to separate inverter under the bed. That way you can shut off big inverter and use smaller one to run tv etc. Or, if only running a small load, find 12 volts in fwd cabinet and use it for a small inverter, [like you have] and you can still turn off your big inverter. On present coach, used both methods. TV is on small inverter using 12 volts in front overhead, and rest of front equipment, on bigger inverter [600 watt] under bed. If i want all fwd equipment, run inverter under bed, if only tv, shut that one off, and big one off and just use small one [300 watt] for tv. It all depends on how much battery and solar you have, and how often you want to run your gen, or need to plug in.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Lighting Wiring capacity

Reply #5 –
Take a look at the beamalarm web site, adding an additional inverter. That's the way I did mine works great.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Lighting Wiring capacity

Reply #6 –
You can do the DPDT switch (manual transfer switch) back in the under bed space but that powers all of your bedroom outlets as well.  Running a hair dryer or electric blanket gets to be a problem then.  Bu splitting the circuit you can isolate the front end electronics.  By running them on a smaller inverter you also eliminate transfer switch timing issues with a big uninterruptible power supply.

I put a DPDT (double pole double throw) switch in the kitchen so that the fron sub circuit can be powered by either inverter or the landline.

By the time you do the work you might as well think it through and make it do the best it can for your purposes.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Lighting Wiring capacity

Reply #7 –
I agree with Roger, think the project through. We do a lot of dry camping, so I set mine up mainly to keep the satillite and tv from resetting every time we turn the inverter on and off, charge phones, and to power a future res refr. I did a 1000W ps under the bed with the sw setup. We rarely use the big inverter only for toast and such. You can also switch the manual between power sources fast enough the satillite never notices.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country