Need Inverter Wiring Help !

[Oilman]

I plan on installing a 1500 watt inverter in my class B MH.
I would like the unit to power all the outlets although it will only really be used for a hair dryer and microwave.

The inverter I am looking at has a built in 30 amp transfer switch and must be hard wired.

The MH has a built in transfer switch for the shore-power or generator.

Can I take the shore-power wires that go into the Motorhome transfer switch and attach them to the inverter transfer switch and in turn attach the inverter to the MH transfer switch ?? Does this sound right??


The 12 volt part seems more straight-forward.

Any suggestions or advise is appreciated

[pianotuna]

Hi Oilman,

What part do you wish me to elaborate on?

I have an OEM 30 amp shore power cord, a 20 amp auxiliary, and 15 amp auxiliary cords.

I originally had a 2500 watt MSW inverter. When situations arose where I only at 15 amp shore power I would "break out" the converter and plug only it into shore power. The OEM 30 amp was plugged into the inverter. So I could use 2500 watts instead of 1800.

Now I have a hybrid inverter capable of 3000 watts. If I enable load support I can draw 25 amps with 15 coming from the shore power and 10 (or 100 @ 12 volts) coming from the battery bank. Granted I can't do it forever but it certainly takes care of running the toaster, induction cooker, and water heater all at the same time on minimal shore power.

If I run the roof air in the mountains I can power the air conditioner, and at the same time draw from the inverter to power the hot water heater. The genny can only do about 2200 watts at high altitudes.

The plugs allow me great flexibility for getting power to the RV.

Feel free to contact me here or in a PM with any other questions you may have about the (highly modified) system I use.

[Oilman]

Thanks everyone for all advice.

What I learned so far....

- My battery bank is marginal at best
- I should get a 2000 watt inverter to play it safe
- a sub-panel is the likely the most fool proof in the long run
although the my original install is a lot simpler

Pianotuna, Could you elaborate a little more on your setup. I am a little confused as to exactly how it works. thanks

[pianotuna]

Hi Jim,

While I'm sure your system works for you, it would not be my cup of tea.

My RV acts as if it were plugged into shore power all the time with 3000 watts of continuous capacity. I can even heat electrically from the battery bank for one night at -5 C.

I often urbandock where there are multiple 15 amp circuits available. So I have the OEM shore power cord, and two auxiliary, one for the converter (and plugs), one for the water heater (and plugs).

I often used double conversion for the OEM circuits where there was only a single 15 amp circuit. My default is for the converter and water heater to be unplugged from the OEM wiring and plugged into the auxiliary shore power cords.

Only the fridge needs to be switched. If I am driving, I operate it from the inverter/battery bank/alternator/solar. In summer time if there is excess solar power I use the water heater on the electric setting for a few minutes so that I'm not wasting solar watts.

It takes about 20 seconds to "patch" the wiring back to OEM.

When you leave a campground, you unplug from shore power and stow the cord. When I leave I unplug from shore power, plug into the inverter and stow the cord.

I can't have the often reported problem of a failed transfer switch. Your system requires at least two transfer switches, and when they fail, (it is always when, and not if) unless there is a way to by pass them the trip may be impinged upon in a negative manner.

I live in my RV full time. I heat electrically down to -37 C. I can't afford to have a transfer switch fail.

Because of the patch board I can run the roof air, fridge, and water heater all at the same time from a Yamaha 3000 iSEB even when I am at 7000 feet in the mountains. If I am driving the engine alternator will provide part of the load. If the alternator shows signs of overload I can switch off the charging path from the engine.

My generator is equipped with remote start.

And those are the reasons for me having a "patch board".

time_to_go_now wrote:

pianotuna wrote:
I use a system of male and female plugs to configure the RV for inverter use.

Who needs a system? Like Wa8 said, inverter to sub panel. Move outlets that need to be inverted to sub panel.

Done. No system of plugs. My family just uses the motorhome. They don't know whether power is coming from shore, genny, or inverter.

Who wants to mess around with plug this and unplug that???

[time_to_go_now]

pianotuna wrote:
I use a system of male and female plugs to configure the RV for inverter use.

Who needs a system? Like Wa8 said, inverter to sub panel. Move outlets that need to be inverted to sub panel.

Done. No system of plugs. My family just uses the motorhome. They don't know whether power is coming from shore, genny, or inverter.

Who wants to mess around with plug this and unplug that???

[pianotuna]

Hi,

Find out the maximum wattage device that will be run. Size the inverter to 125% of that number. The microwave in my unit draws 1591 watts. Therefore I would need a 1989 watt inverter.

1591 watts presents a load of 160 amps to the battery bank. Thick short cables are a requirement.

I use a system of male and female plugs to configure the RV for inverter use. The only switch I need to change is on the fridge.

[wa8yxm]

Motor home existing breaker box.. Install a 30 amp breaker Then...

10 or 8 ga wire (Romex) to inverter's AC-IN connections... then options

1: Inverter has no breakers
Run same size wire back to a spot near/behind the existing breaker box

Install SUB PANEL

Move circuits you wish to be INVERTER powered to breakers in the sub panel

job done (in many cases you can use the existing breakers but put spare/dummmy breakers in the vacant slots)

Option 2: Breakers on inverter

15 amp breakers use 14 or 12 ga from the inverter to a Junction box behind or near the existing panel,,, Transfer 1 circuit per breaker to this box

20 amp breakers 12 or 10 ga

NOTE: in all cases the smaller wire (Larger number) meets code but wire makers today... Some of them several forum members think they are short-sizing.. So I gave the larger wire as an option.

With this hook up

Generator will operate the existing ATS and send power TO the inverter which will stand by and pass through

Shore power.. Same as aboe

NO shore/generator the Inverter will take over. But only the lines transfered.

DO NOT transfer your conerter.. Depending on the existing converter you may choose to

1: Disable it
2: Disable the one in the inverter

(NOTE: I have both connected, Use he OEM (I like it better) but if I screw up and pull a plug.. Well I can activate the INERTER's converter at 3am during a downpour rain and not have to get dressed or wet.

[MrWizard]

run the 'B' engine if you want to use the hair dryer or bake a potato, be sure everything else is off, you do not have enough battery to spend ten minutes drying wet hair

be sure your fridge is on LP..manually and can NOT autoswitch to AC

[2oldman]

Oilman wrote:


I had not thought about the converter. Hmm..

put an spst kill switch on one of the 120v feed wires.

And I also concur that just 2 batteries will struggle with that big load.

[time2roll]

Marginal and will limit your run time. AGM does help though.
If you have space for more I recommend it but I am sure things are tight.

[Oilman]

smkettner wrote:
Yes that placement in the circuit will work. It will supply power to everything so be careful with what is on such as converter, 120v fridge, 120v water heat etc. As an alternative get a straight inverter and separate transfer switches for just the circuits you want powered up.

+1 need to verify the INPUT wattage of the microwave or go 2000 watts.

Generally you should have three or more batteries driving this inverter... what do you have?

Error on the large side for 12v connection.

I have 2-12 volt agm.

[Oilman]

2oldman wrote:
Keep in mind that your scheme is a 'whole house' install, meaning you don't want your water heater on, or your converter, or your a/c when on inverter power. Just be mindful of that when inverting. I've done it for years.

I'm not a fan of using subpanels. Lotta work.

I was trying to keep it simple which is why I wanted to do do it this way. The sub-panel may be beyond my DIY skills.

I was aware of the AC and water heater issue and they would be easy to leave off.

I had not thought about the converter. Hmm..

[time2roll]

Yes that placement in the circuit will work. It will supply power to everything so be careful with what is on such as converter, 120v fridge, 120v water heat etc. As an alternative get a straight inverter and separate transfer switches for just the circuits you want powered up.

+1 need to verify the INPUT wattage of the microwave or go 2000 watts.

Generally you should have three or more batteries driving this inverter... what do you have?

Error on the large side for 12v connection.

[2oldman]

BFL13 wrote:
Next, question whether you really want/need an inverter/charger which is expensive, when all you need is the inverter.

The OP's link shows only an inverter.

[BFL13]

First check the input watts on its label on the back needed to run the microwave. EG a "1000w" MW might want 1500w input. The PSW 1500w inverter would be maxed out. Might get away with a "900w" MW.

With a B you will have limited room or weight for a the usual four batteries needed to run microwave type high amp drawing loads. However, AGM batteries are much better at this, so if you can only carry two batteries, have AGMs for that job.

Next, question whether you really want/need an inverter/charger which is expensive, when all you need is the inverter. The B will already have a converter.

You could use the money saved there to buy the AGMs.

There are several wiring options for inverters that have their own receptacles but limited options for hard wired ones.