My Inverter Installation

Once I had completed my power calculations and determined what type of equipment that I wanted to use, I settled on a Magnum Energy MS2012 2000 Watt combination inverter/charger.  The MS 2012 produces a “true” or “pure” sine wave as opposed to a modified sine wave.  The reason I chose an inverter capable of producing a true sine wave was because I had planned on installing some audio/visual equipment (notably a 32 inch LCD TV and satellite TV box) and I did not want to suffer from any electrical noise.  Likewise, I knew that I could use any appliance with a true sine wave inverter and I did not want to limit myself in any way.  Of course, the down side to this decision was that I had to pay more money for the inverter than I would have if I had chosen to use a modified sine wave inverter.

(Picture of the Inverter I Purchased)

Although I am a handy person and I can figure most things out, I am not an electrician by trade so I had to proceed carefully.  Installing the inverter in my RV required me to add a breaker to my AC panel, rewire some of my RV’s existing electrical system, and add an additional circuit with multiple AC receptacles.  Therefore, before starting, it was important to know exactly what I wanted and what I didn’t want and to plan carefully. This was especially important since I knew that I was voiding most of my warranty and no one would bail me out if something went wrong.

For background purposes and so that you can follow along, it is important for me to explain my RV setup and what I wanted to accomplish.  We bought a brand new Keystone Raptor 3612DS.  The 3612DS is a 5th wheel toy hauler that has a garage space in the rear that is separated from the rest of the RV by a wall and door.  In the middle is the kitchen/living area and in the front is the bedroom.  I knew that I wanted to replace the 25” standard (cheap) TV in the living area with a new 32” flat panel LCD TV, add a satellite TV receiver, satellite Internet equipment, and a wireless router.  Since the existing TV was on a shelf above the door, I had planned on removing the TV and building additional shelves in its place and locating all the equipment on the new shelves with the flat panel TV mounted on the outside (this modification will be documented on this site as well).  I wanted all of this equipment to run off the inverter.  I had also planned on installing a small flat panel TV in the bedroom up front and I wanted that to run off of the inverter also.  Additionally, I wanted to be able to have various outlets in my RV powered by the inverter, including outlets in the garage.  Since the garage also had beds that came down off the ceiling, I figured I might want to have a TV for guests in there or that I may need to use some power tools in there someday.

In addition to knowing what I wanted, I also knew what I did not want.  I did not want to run the air conditioners or the microwave off of the inverter.  Air conditioners require too much power and in order to run an air conditioner off of the inverter using battery power I would have needed a battery bank approximately the size of Rhode Island (OK, slight exaggeration).  Similarly, the microwave required a lot of power and I figured for the short amount of time that we actually used the microwave, I could power up the generator.
Before I started the install, I took the time to figure out which outlets were on the same circuit.  I did this by turning off each breaker and testing the outlets.  To my delight, I found that most of the outlets in the bedroom and in the living area were on the same circuit with nothing else attached.  Unfortunately, however, the outlets behind the TV shelf and in the garage shared the same circuit as the microwave, which presented me with a problem.  The inverter that I purchased was capable of powering two AC circuits.

This is what I did:

• I switched off the AC breaker for the built in battery charger that came with the RV since my new combination inverter/charger was going to handle charging the battery bank.  Since I simply turned off the breaker, I can turn it back on at any time if I need to.
• My inverter required a 30 Amp circuit to provide it with sufficient power when plugged in or running off the generator. Therefore, I installed a new 30 Amp breaker into the existing AC panel and connected it to the AC “IN” on the inverter using 10 gauge household Romex wire (the same type you would use to run electrical circuits in your home). I had to be very careful to make sure the AC panel could handle the additional 30 Amp circuit.  The AC panel was rated at a certain amount of total Amps.  If I had not switched off the charger and removed one of the other circuits (more info on this in the next step), I would have exceeded the total amount of Amps the panel could handle despite the fact that it had open slots.
• I disconnected the wiring that fed the AC outlets throughout the bedroom and living area from the breaker in AC panel.
• I ran two new circuits off of the inverter and connected them to two new 15 Amp circuit breakers in a new 30 Amp breaker box that I installed near my inverter in the basement compartment.  I purchased the breaker box at Home Depot and used 10 gauge Romex wire to make the connections.  The purpose of this new breaker box and circuit breakers was to protect the circuits from overload and provide a way for me to power off the circuits if I needed to do any maintenance or add additional wiring in the future.
• I connected one of the new 15 Amp circuits to the existing outlets in the RV that I disconnected from the original AC panel.  I used 10 gauge Romex to run the wiring from the new breaker box to a location behind the existing AC circuit breaker.  I installed an electrical box and spliced the wiring together and covered the box with a blank plate.
• I used the second circuit from the new breaker box to create a new circuit with new outlets.  Once again I used 10 gauge Romex. The new circuit ran behind the television equipment where I installed a new outlet and continued through the cabinetry (to hide it) and through the wall to the garage where I installed a new outlet (so that I could have inverter power in the garage).  Since this wiring was not fished behind the walls and in some cases ran inside the cabinets, I encased the Romex in electrical conduit (available at Home Depot) to protect the wiring from chaffing and damage.
• I connected the inverter to the battery bank using 3 feet of 3/0 gauge battery cabling that I had custom made with the proper sized terminals for my batteries.  I purchased the cables from the same place that I got the batteries.
• I installed a remote panel on the same wall as the existing RV monitor to control and monitor the inverter from inside the RV.  The remote panel connected to the inverter with a telephone cable that came with the kit.  With the remote panel in place I can monitor the inverter, batteries, turn the inverter off and on, and configure the inverters settings.

Following is a simple diagram of my configuration:

Here is a picture of my inverter installed in the basement compartment:

(Click on the picture for a larger view)

A Few Last Notes:

• Even though I spent a lot of time planning my installation, there is one thing that I wish I had done differently.  If you have read some of my other articles, I have always advocated using stranded wire instead of solid wire (like Romex) in RV applications.  The reason is because stranded wire is more flexible and better suited for an RV that is going to experience a lot of shaking and rattling as it travels down the road.  Solid wiring can crack and break over time under these conditions. Even though I knew this, I still used Romex to complete my AC wiring runs. The fact of the matter is that we had a large trip planned and I was running out of time with all the modifications I had planned.  Using Romex was easy and it was readily available at Home Depot. If I had to do it again, I would use stranded wire, and I recommend that you do also.  Just be sure to do your homework and make sure you get the proper sized wire for your application.  Safety first!  Although this bothers me to this day, in the long run I am not sure that it should really bother me as much as it does since the original AC wiring used by the RV manufacturer was also Romex.  It just goes to show that most RV manufacturers use what is cheap and easy as opposed to what works best for the given application.
• When installing your inverter try to locate the inverter as close to the batteries as possible. Ideally you do not want the cables between the batteries and inverter to be longer than 3 feet. In a worst case scenario the cables should not be longer than 10 feet (this is because the guage of cable that you need gets larger with the length of the run. Although it is possible to go further than 10 feet, the gauge cable needed may make it difficult or impossible to find). Make sure to use the correct gauge battery cables for the application. The manufacturer's installation instructions should have some guidelines on the gauge of cable that you should use in relation to the length of the cable run. Remember that the inverter will be drawing a significant amount of power from your batteries and if you do not use the correct gauge cable for your application the inverter won't perfrom optimally, the cables may become hot due to the resistance in the wiring and could ultimately cause a fire. Safety first!
• Make sure to use the same legth cables between all the battery connections. Also, be sure to use the same length cables to make the connection from the batteries to the inverter.
• Make sure that you mount your inverter in a space that has some ventilation. You do not want your inverter to become overheated and fail.

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