I don’t have a lot to say about the background to this modification, other than the money we spent is considered insurance and peace of mind as we operate our motor home all over the place in all kinds of campgrounds and in all kinds of weather. There is a good amount of details available out there on the web to those who are considering an EMS purchase.

We chose the Progressive Industries EMS – HW30C as our EMS. The company looks to have excellent product support and installation videos, and some folks have detailed their installations on YouTube as well. One source I found quite useful during this research and installation was Grandpa Ron’s YouTube channel “On the Road with Ron”. Grandpa Ron has a View as well, and his information found in his “RV Surge Protector” video made a lot of sense to me. I essentially duplicated his install, but plan to mount the display on the panel with the water tank heaters switch. I think it will be useful to see how much current we are pulliing when we use a combination of appliances on shore or generator power. The Xantrex XC has that information, but is pretty course.

Progressive Industries HW30C EMS

Do you need one? That depends on your comfort level, I guess. For lightning strikes, I think you would be Ok without one as there is a surge suppressor built into the 2020’s new automatic transfer switch hooked up downstream of the shore power. For every other electrical hazard that can cause grief to onboard equipment and inhabitants in our motor home? No, there is no protection from these other hazards, so we spent the money to not have to worry about them. (We did not have an EMS on our previous Class B motor homes, but we felt we wanted to do it right on this purchase.)

The install was straightforward, but as Grandpa Ron indicated - installing the box in the location of choice was a bit of a pain. Does it have to go there, under the bed? Well, no… but it makes the most sense to put it there. The orange 10 gauge / 30 amp cable coming from the automatic transfer relay feeds into the main AC circuit breaker box under the bed, and this EMS needs to be installed upstream (before) that happens. Under the bed makes the most sense, due to the proximity to the main AC circuit breaker box and having the most space to work in.

The supplied installation instructions describing the install after the Onan Genset auto transfer relay are overly complicated, having to ensure they cater to the worst case scenario for shore power / genset wiring. The idea here is to install it after the genset auto transfer relay, so you are covered for either raw AC shore power or AC coming from the genset. All I did was locate the orange 30 amp feed cable coming from the shore power / genset auto transfer relay, and decide where to sever the line to make the install. You will see the cable was easy to find, and there was floor space just ahead of the water pump; same as Grandpa Ron’s video shows.

I elected to mount the EMS on a plywood base, just in case there was ever a plumbing leak in the area:

Here is where I ended up putting it; the orange 10 gauge cable is at the bottom of the photo:- (The other orange cables are extension chords for my plumbing heat mods)

This photo shows everthing hooked up:

And this one is the EMS all buttoned up:

So, all in all, that was sort of the easy part. (Well maybe not easy, as crouching under the bed to do the wiring was kinda annoying) The part that took the longest was the mounting of the remote gauge in the location I wanted - in the cabinet where the Xantrex inverter control is. The trick here was to remove the cover panel in the cabinet, unplug the inverter com cable and the DC inputs for the tank heater switch, and get access to the space above the refrigerator from the hole in the side of the cabinet. I tried two or three ways to get an electrician’s cable puller into the area by the Truma water heater, and finally had success by starting the fishing expedition from on top of the refrigerator. By removing the three screws on the fridge control panel, the whole cover panel slid out and revealed the top of the fridge.

I inserted a cable fisher in the back right corner and went straight down the back right side of the fridge. The cable fisher popped out down by the water heater. Once I had the cable from the EMS on top of the fridge, it was easy to get it over to the the hole that opened into the cabinet above the cooktop.

Here is a shot of where I started the electician’s cable puller down the back of the fridge:

I did this gauge install in conjuction with the gauge install for the Victron BMV 712, so I only had to do all of this once. Here are some photos of my gauge layout, hole location, the various cables that needed plugging into the gauges, and the end result: (Winnebago chewed up the face plate holes a bit, so I changed out the screws and added some washers to make things look a bit better)

The EMS works very well - on the first power up it caught the fact that the extension chord I was using from the garage did not have a ground prong attached. I had to think about that for a minute, but then finally realized that the EMS was quite right - there was no ground. Once I changed out the extension chord for one with a ground prong - the EMS error code cleared, the box allowed power to the coach, and all was right in the RV mod world again.

Interesting NOTE - The new EMS has tighter over-voltage protection than the AC voltage our particular Onan Genset likes to output. If the Onan has been running for a few minutes and just under a min load to charge the batteries, it is not uncommon to see the AC voltage on the new gauge start to creep up into the mid to high 120s and the EMS react by shedding the AC power from the generator. This results in some generator surging as the EMS periodically allows the power to re-connected to the coach after the voltage drops a bit. The solution to this was to use the Bypass switch on the EMS panel, to allow the generator power to enter the coach without going through the EMS itself. I’m not sure if this voltage creep is just a characteristic of our particular generator, or if they all do this under minimum load. I’m thinking that maybe it is just ours, as I have not read about other people having similar troubles. I’m Ok with running the generator and not having the EMS protection - my main concern was campground power - but something to keep an eye on, I guess. Let me know if you’ve seen this too?


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