Inverter: Where to start? Subpanel or No Subpanel?

[tsweez]

Thanks in large part to the community here, this new RV'r just finished his first mod, e.g. creating a new battery location and replacement of the power converter/charger. My next project is installing or at least "preparing" for an inverter installation. I'd like to do as much of this as possible as to control cost, but under no circumstances do I want to sacrifice safety. If I can get this most of the way complete, I'd be a happy guy.

Here's the scoop...

The scope is to install,(as much as is safe) a 12v Cotek 1500 PSW inverter. This inverter has an internal transfer switch and AC breaker. I want the inverter to power all my coach outlets except for A/C and the Microwave. I don't want any manual switching here at all, rather, have inverter setup so it acts much like a UPS in the absence of shore or generator power. Likewise, I want the inverter to bypass should shore or gen power be available.

For reference, my AC panel already has the Microwave and Air Conditioning on their own breakers. The remaining coach outlets (the ones I want on the inverter) are all on the same breaker including the GFCI outlet in the bath. This breaker is also wired to my converter/controller with what appears to be a pigtail of sorts (pic below).

Pic of panel

Pic of breaker w/pigtail

Questions

• Since the coach outlet wiring is already isolated, do I need a subpanel here?
  
• Do I need to separate the house wiring from the exist breaker that also shares the controller/charger?
  

Again, if I need to pay someone to do this, I will. I'm just trying to save as much as I can and move the project in a direction that I know is both safe and effective. The last RV shop I went to was going botch this whole thing and I just want it done right, and for as little as possible.

Thanks again for your help.

Tim

[michelb]

One other pro argument for 'no sub-panel' is that it's kind of nice that ALL outlets in the motor home get power from the inverter.

We were camping without hookups in our 'new-to-us' Phaeton this weekend which has a sub-panel and I realized that while in our old mh (where I installed the inverter with no sub-panel) all the plugs were powered, in this one, only a select few are powered so you have to know which ones they are and plug things in accordingly.

[mena661]

X2 Nice job!

[time2roll]

Nicely done :B

[tsweez]

Okay, so now my 2nd mod is behind me. I decided to go with smkettners suggestion which worked well and I'm quite pleased.

The first thing I did was to add another 15 amp breaker and move the outlets to their own circuit. This was much easier than I thought it would be. I simply removed the pigtail that combined the charger/controller to the outlets and ran each to their own breaker.

After that, I ran two strands of romex from the panel to the bay adjacent to my new battery bay. I spliced one of these runs to the romex that fed the outlets which became my AC out on the inverter. The other romex was wired to the breaker and that fed my AC "in" on the inverter.

Everything works great, including the built-in transfer switch. If I'm running the gen and turn it off, the inverter kicks in immediately. Conversely, when the gen comes on, the inverter goes off-line. Same of course for shore power.

To me, that transfer switch was really a safety feature. I have the on/off remote routed to the inverter so I can turn it on when I want at the touch of a button which is really what I intend on doing. The only thing I need to remember is to switch my fridge to propane when I'm on the inverter.

Inverter Install Pic

Special thanks again to the awesome folks here. For a new RV owner who possesses only moderate DIY skills, these conversations have been invaluable.

Until next time!

Tim

[donn0128]

pianotuna wrote:
Hi donn,

Wow, sounds like a lot of work. Did you surface mount the wiring?

My system has one dedicated outlet in the kitchen, and one in the shore power cord box area. Due to the location of the inverter behind the driver's seat I also have access to 120 volt power in the cab.

My converter plugs in and I have auxiliary shore power cord--so I leave it connected to that as a "default". I do change the fridge to propane. The default on the water heater is "off".

donn0128 wrote:
I did a down and dirty and would do it again in a heart beat. I simply wired dedicated inverter outlets where I wanted power.

No, it was actually quite easy. I knew where I wanted inverter power, ao some planning and careful drilling got the wire where I needed it. Snce I had access behind both places it was only a matter of temporairly removing a few things, making a hole connecting the wires and screwing the outlet in place. I added a lable to each outlet indicating what sort of power it has. If I forget and leave the inverter on, the worst thing that will happen is my batteries will be drawn down. I have actually done a similar thing with my satellite cableing. Two outlets, one for roof top and one for ground satellite antenna.

[wa8yxm]

If it is just one breaker's worth of circuits (or even part of one) you plan to put on the inverter, and it appears it is.

And if the inverter has an internal transfer switch and breaker

No need for a sub panel

Existing breaker (Tap to converter)----Inverter---It's breaker---Outlets

[michelb]

I did the whole panel because it seemed easier to me than installing a sub-panel (installed it myself). It works fine this way except that you have to remember to switch the fridge to gas manually when you don't have hookups otherwise it will run the fridge from the inverter. It will also try to run the roof A/Cs but that will overload the inverter, which seems to have good overload protection, so you just have to turn off the A/Cs and then reset the inverter.

[2oldman]

tsweez wrote:
don't I have to switch off the breaker that feeds the charger/controller

Yeah. I put an spst on the 120v feed to my converter. Been off for 10 years.

[tsweez]

Yes, the Cotek is a pure sine wave unit. It's my understanding that it's a more industrial version of the Samlex line made for emergency vehicles, etc. It doesn't have plugs but I'm not sure I want to go the manual route as I like the idea of a simple one button press for the inverter not to mention, only powering outlets I know it can handle. I get thick sometimes, and this would provide me with some comfort. Not to mention, it appears as though I still have to tweak the breaker config so I don't turn off the outlets at the same time I turn off the controller/charger. But I do like the power conditioning affording by the whole house approach.

As for the location, yep. The inverter will be very close to batteries. I created a new enclosed and vented battery bay with the inverter positioned just on the other side of the divider. I also have the inline fuse all ready to go. Geesh I love the internet. Between you great folks and a wealth of information, it sure can be empowering.

-T

pianotuna wrote:
Hi tsweez,

Is the Cotek a pure sine wave unit?

Check to see if the converter plugs in. Mine does. If yours does not, add a female plug and a male plug. Or add a switch. I do prefer the plug as it allow for double conversion when there is poor quality shore power.

I see no advantage to using an "internal to the inverter" transfer switch. Sooner or later the contacts may burn. When they do *ouch*.

Just use the KISS principle when installing the inverter.

I.E. as close as humanly possible to the battery bank, without being in the same compartment, and plug in the existing shore power cord.

tsweez wrote:
For reference, the Cotek I have does have a built-in 30amp transfer.

[pianotuna]

Hi tsweez,

Is the Cotek a pure sine wave unit?

Check to see if the converter plugs in. Mine does. If yours does not, add a female plug and a male plug. Or add a switch. I do prefer the plug as it allow for double conversion when there is poor quality shore power.

I see no advantage to using an "internal to the inverter" transfer switch. Sooner or later the contacts may burn. When they do *ouch*.

Just use the KISS principle when installing the inverter.

I.E. as close as humanly possible to the battery bank, without being in the same compartment, and plug in the existing shore power cord.

tsweez wrote:
For reference, the Cotek I have does have a built-in 30amp transfer.

[time2roll]

tsweez wrote:
Quick Question...

Since my charger/controller are on the same breaker as my house outlets, wouldn't that create a problem if I did "whole house?"

Sorry if I'm dense here, but don't I have to switch off the breaker that feeds the charger/controller when I want to use the inverter? And by doing so, wouldn't I be switching off the outlets at the same time?

Thanks in advance for your patience 🙂

Tim

Yes and since you said no extra levers, switches, buttons to activate I recommended powering the single circuit and put the converter on it own separate breaker. No issues no worries. Very straight forward connections. Hit the inverter remote and instant power.

[BFL13]

Correct. In that case you have to separate them better. The black wire coming up from the converter to the breaker needs to be snipped before it joins with the receptacles' black wire to the same breaker.

You can then run that black converter wire to a switch and then rejoin it to the same breaker on the other side of that switch (what I did) or to its own breaker if there is a spare slot on the AC buss, or to a different item to share with, such as the water heater, which you then only ever use on gas. Anyway, you must do something.

The main thing to remember when sharing is that the total amps cannot go over that breaker's rating should you want to have all on at once when on shore power. You can't just allow for being on inverter off-grid.

[pianotuna]

Hi donn,

Wow, sounds like a lot of work. Did you surface mount the wiring?

My system has one dedicated outlet in the kitchen, and one in the shore power cord box area. Due to the location of the inverter behind the driver's seat I also have access to 120 volt power in the cab.

My converter plugs in and I have auxiliary shore power cord--so I leave it connected to that as a "default". I do change the fridge to propane. The default on the water heater is "off".

donn0128 wrote:
I did a down and dirty and would do it again in a heart beat. I simply wired dedicated inverter outlets where I wanted power.

[tsweez]

Quick Question...

Since my charger/controller are on the same breaker as my house outlets, wouldn't that create a problem if I did "whole house?"

Sorry if I'm dense here, but don't I have to switch off the breaker that feeds the charger/controller when I want to use the inverter? And by doing so, wouldn't I be switching off the outlets at the same time?

Thanks in advance for your patience 🙂

Tim