Inverter Wiring

[BNB187]

Hello

I have a 2021 183RB. Have a chance to pickup a WFCO WF-5220 inverter brand new for less than half of retail. Trailer is not prewired for inverter.

What is the best option for wiring this in? I assume as close to the battery as possible to keep the DC cabling length as short as possible. But then what? Run a junction box behind the power center and run the shore power AC wiring to the inverter and another line back from output of inverter to main breaker? Will this inverter allow 30amp pass through when hooked up to shore power or will the output on shore power be limited to 2000w as well?

I really don’t care if the input side is used can just activate inverter manually as well. But then what is the best path for wiring? Is it as simple as tying the output and shore power wire together and then a wire to the main breaker? This would have shore power backfeeding AC power to the inverter when plugged in. Does this matter?

Any help is appreciated!

Thanks
Mike

[CJAZ]

Mike,
I see you haven't gotten any responses. I hope I can help out as I've completed this type of installation in a few instances.

Originally Posted by BNB187

Trailer is not prewired for inverter.

Doesn't really matter - may of the "pre wired" loops only feed one or two outlets and are IMHO quite useless. Some are true full amp pre wires, many are not.

Originally Posted by BNB187

What is the best option for wiring this in? I assume as close to the battery as possible to keep the DC cabling length as short as possible. But then what?

Yes, with many inverters being mounted in the pass through in the nose close to the batteries. You'll need to use thick wire, likely 1/0 ga to connect batteries together and to get to the inverter such as this.

this is a nice one we used and were happy with:
https://www.amazon.com/gp/product/B0CFDGMLV2/
You'll need a lug crimper:
https://www.amazon.com/gp/product/B083J13VG5
you may need extra lugs or extra length depending on your setup.


Place a 200 or 250 amp DC fuse or breaker as close to the battery as possible.

For the AC side of things, you'll want to run the appropriate ga wire to somewhere behind the power center. How you get there depends, but I find rather than tearing down the belly shield which is an option I have just run the wire in conduit back out the nose, and alongside the frame rail inside conduit, then penetrate the belly somewhere close to where you will enter behind the main panel. Much easier and works out great. Run a long RJ11 or RJ12 cable or ethernet in there as well if you want your inverter remote to be somewhere inside in proximity to the main panel. Many times you can hide the remote wire behind cabinets or under the counter to get where you want to be without pulling wall panels.


When doing this I prefer UF cable, but regular romex is fine as long as the correct ga for your amperage.


Once behind the main panel, Wire the inverter back to the main shore power inlet with a 30 or 50amp auto transfer switch and appropriate ga wire. Manual switches can be used but I'll show you a shortcut that makes the auto transfer just as inexpensive.

Most people use this type of transfer switch, we have one and it works great:
https://www.amazon.com/Go-Power-TS-3.../dp/B00153EYTO

There are a bunch on Amazon around $100 - $150. 2 things nice about these are the larger black box to hide the wires, and most include a 20 second delay between plugging in shore power and the switch activating (nice with generators).

What is inside of this doing all the work, except for the 20 second delay, is this:
https://www.amazon.com/gp/product/B07FCJFGL9
so for $20 you can make your own tansfer switch without a delay. The only drawbacks are no larger box, no pre-made leads, and no 20 second delay. Less than the price of many manual switches and does the job great. Pick up appropriate wago or that style lever nuts and the wiring is a piece of cake.


NOTE - pull the neutral from your converter out of the main panel and wire it directly to the neutral from the shore power cord on the transfer switch. This does 2 things - it removes the converter from the circuit when on inverter power, AND it allows the converter circuit breaker to still work so that you can manually turn it off if desired such as when using a generator and powering the AC.


I've seen all kinds of complicated and crazy ways people try to accomplish this with relays, etc. This is the simplest, easiest, and most effective solution in my opinion.


It is VERY important to do this, or when you power on your inverter you'll create a loop of trying to charge the batteries with inverter power from the batteries and will cause a voltage drop and inverter error.



Hope this helps, take it step by step and it's pretty straightforward but sounds like a lot at once.

Originally Posted by BNB187

This would have shore power backfeeding AC power to the inverter when plugged in. Does this matter?

YES, it does matter with most inverters - I am not sure about your particular inverter but avoid that situation.

If you have any questions let me know.
Best Regards!
CJ from AZ

Originally Posted by BNB187

Hello

I have a 2021 183RB. Have a chance to pickup a WFCO WF-5220 inverter brand new for less than half of retail. Trailer is not prewired for inverter.

What is the best option for wiring this in? I assume as close to the battery as possible to keep the DC cabling length as short as possible. But then what? Run a junction box behind the power center and run the shore power AC wiring to the inverter and another line back from output of inverter to main breaker? Will this inverter allow 30amp pass through when hooked up to shore power or will the output on shore power be limited to 2000w as well?

I really don’t care if the input side is used can just activate inverter manually as well. But then what is the best path for wiring? Is it as simple as tying the output and shore power wire together and then a wire to the main breaker? This would have shore power backfeeding AC power to the inverter when plugged in. Does this matter?

Any help is appreciated!

Thanks
Mike

[BNB187]

Thanks for the indepth reply!

For the AC side of things, you'll want to run the appropriate ga wire to somewhere behind the power center. How you get there depends, but I find rather than tearing down the belly shield which is an option I have just run the wire in conduit back out the nose, and alongside the frame rail inside conduit, then penetrate the belly somewhere close to where you will enter behind the main panel. Much easier and works out great. Run a long RJ11 or RJ12 cable or ethernet in there as well if you want your inverter remote to be somewhere inside in proximity to the main panel. Many times you can hide the remote wire behind cabinets or under the counter to get where you want to be without pulling wall panels.

The WF5220 inverter has an AC input and AC output and handles transferring internally. What I can't seem to get a 100% solid answer on is if when on shore power if it will pass through more than the 2000w the inverter is rated to. I assume so as the spec sheet mentions a 30a DPDT relay for this.

NOTE - pull the neutral from your converter out of the main panel and wire it directly to the neutral from the shore power cord on the transfer switch. This does 2 things - it removes the converter from the circuit when on inverter power, AND it allows the converter circuit breaker to still work so that you can manually turn it off if desired such as when using a generator and powering the AC.

I actually really hadn't considered this part of the situation. I'm wondering if a contactor might be a reasonable option as well. From the breaker in the power center to NO terminal on the contactor and fire the contactor from the shore power wire with load side connected to the converter wire.

But then again your solution does sound a whole lot easier!

[CJAZ]

You're very welcome.



I'm not familiar with that particular inverter, but typically inverters are mounted somewhat close to the batteries, and commonly in the front pass through storage.


If the inverter is also acting as the transfer switch it would require you having 2 runs of appropriate ga AC wire - one running from the shore power plug to the inverter, and another running from the inverter back to where the shore power plug entered the main panel.



In this scenario, you'll be pulling the shore power from the back of the main panel and using a junction box to extend it to wherever the inverter is. As long as that inverter is acting as a proper transfer switch and disconnecting that side when on inverter power, then the trick with the converter neutral should still work. If I'm picturing the set up correctly it seems like you can just pull converter neutral from the main panel and join it to the shore power neutral at the same junction point where you'll need to extend the wires to get to the inverter shore power input side.



I've played around with contactors, relays, etc - they all tend to make a slight buzzing/humming noise and many get warm/hot to the touch when in use. I decided I needed a simple way to isolate the converter, but I really wanted the stock converter breaker to retain it's usage when we run our small-ish portable generator for the AC and need all it's power. The neutral re-wire does the trick with no additional equipment needed.