When inverters are permanently installed in RVs, there are 2 ways it's done: energizing specific circuits, or energizing the entire coach. The first consists of using a subpanel (an additional electrical panel with breakers) ; the second uses no subpanel, and is installed (electrically) before the main AC panel.

As you might imagine, the first is more foolproof (you can't run your air conditioner from batteries by mistake) but, it's much more labor to install. You have to pull wire and find a place to put the new panel. The second is easier, and acts the same as plugging your coach into a generator.

My inverter, a Xantrex Prosine 2.0, is done the second way, called whole-house. Not only is it easy to install, but the best part is something you may not have even thought of that inverters are capable of - circuit protection. Many Xantrex inverters have this feature built-in for anything downstream of their pass-thru AC. I have surge and sag protection, and even bad frequency protection. That's a life-saver when you're in a park with inadequate wiring and brownouts. The inverter can be the power police for your entire coach.



Design
I want to be able to run everything.. every outlet in my coach. That's a nice idea.. but, I know I can't be running the water heater or air conditioning, but, I was not excited about digging into the electrical panel and separating out the circuits. The advice I got on rv.net said a 'subpanel', or, a separate electrical panel dedicated to serving the inverter's power was the safest way to go. Yeah, but how much work is that? A lot.. but I'll talk more about this in the last section, Risk vs Reward.

Ok, I can remember to turn those things off. I remember to turn off the hot water, refer and a/c when I'm on my generator, so I guess I can do that when inverting. Now, how do I connect the wires.. where in the circuit does it go? How big? Let's see.. what's the biggest item I'll need to run? The microwave. How many watts is that? Open the door.. there it is.. 1500watts. Will a 2000 watt unit will be sufficient? According to more research, yes.

I'll digress here for a minute. I don't like cheap products - I've never had good luck with them. And that's what you need.. luck. They either come with problems or cause problems. Cheap products often surprise you with what they don't do.. "gosh, it doesn't do THAT?" or "it doesn't come with that?". Oftentimes you'll discover this well after any warranty has expired, or it's too inconvenient to return it. One example is running a MW (microwave) on MSW. Many people have found out the hard way it takes twice as long to heat. Good quality products often will surprise you with what they DO. That's a much nicer surprise than the other kind. Saving money is not the goal, getting a reliable working electrical system is.

If I want the IC to act as if I've just plugged into a generator, then perhaps I could think of the IC as a generator and plug into it. (By the way, that's a really easy way to have a whole-house inverter sans a lot of work.) That could work, but I want it mounted permanently, seamlessly. I'm not going to want to crawl into the basement every time I want to use my inverter. No, I needed it permanently mounted, permanently in the circuit, and electrically installed to feed the AC breaker panel. ( I reasoned that ALL 120vac had to go through the ac panel before going anywhere else, and it does). And to do that, I needed to buy the "pigtail" version of the inverter. That means the AC side of the inverter (where the shore power comes in to power its charger) must be capable of being hard-wired in via small wires...pigtails. And that's what I got. I want my IC to be: PSW, 2000 watts, hard-wire pigtails for AC, suitable for 30amp service.

The 5er I bought came with a big battery compartment in the 'basement' with a rollout tray. Nice. Now, where to put the inverter? Ah, right on top of the battery box is perfect. That's close to the batteries to keep the battery cables as short as possible, plenty of ventilation, and not in the same compartment with the batteries. This design was not an accident. I made sure the coach had sufficient battery space before I bought it.

IC (yellow) sits atop the battery compartment next to the solar controller (black)

Batteries (6) sit below the IC on a roll-out tray. Big black cables go thru the top to the IC

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Installation

Ok, the plan is in place. I need the IC's "pass through" AC to be between shore power and the AC panel. In the diagram below, that would be from A to C. When you connect to shore, you want power going thru the IC to the main panel. That seems simple: when I'm plugged into shore, I want shore power in my coach. When I'm not, I want the IC's inverted power in my coach. How does that happen? That bit of magic is handled by a transfer switch. More on that later. Electrically, we're set.

Schematic diagram of my electrical system.

Now, let's see how that physically works. I had to find a suitable place to 'intercept' the incoming shore power cord. I simply followed it as it entered the coach, and, voila, found the junction box pictured below. I opened the box to see what I would be dealing with. Good.. the wire to the panel was wire-nutted to the incoming shore cable. No problem. I disconnected each and connected Romex (household) cable to them. One orange wire goes to the IC, the other comes from the IC and connects to the existing cable to the electrical panel. I was very careful to make sure the white and black wires were not reversed at either end. That's it for the 120v side. Simple huh? The picture below is what A to C looks like physically:

This is the junction box where I disconnected the shore cable from the a/c panel wires to splice in the 120vac supply wires to the IC

Some magic things happen while the shore power is "inside" my IC. It's constantly being monitored for voltage and frequency, protecting my valuable electronics from damage. This is especially important for my air conditioner, which can be ruined with low voltage. And this is probably the greatest benefit from installing an inverter "whole house." You get all this wonderful protection from power problems. I don't have to buy a surge guard! And all this neat stuff.. inverter, 'surge guard', battery charger.. it's all in one box.

This is the physical connection wires to the inverter's 120vac side. Those orange wires come from the junction box connections shown above. The gray wires are the connections to the control panel located inside the coach, and the battery temperature sensor mounted to one of the batteries.

This is the 12vdc side. Those huge black wires come thru the roof of the battery compartment. The silver lugs are secured to the cable with a set screw. The smaller wires are from the solar panels (controller). Putting them there is much easier than going to the battery.

Referring to the blue schematic diagram:

Letter D in the schematic diagram is this spst switch. I drilled a hole in the metal plate. It switches one of the converter's 120v feed wires. You don't want your converter on during inverting, and my IC has a much better charger in it.

B, E, F is the picture of the 12v terminals above. Need more xfer switch discussion here... (under construction)....