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windsorbill · 05-11-2019, 05:02 PM

When the coach is on shore power, all 110 volt outlets read correctly on my plug in tester (it has 2 yellow and 1 red light to identify what condition the outlet is in).

Now, I unplug the coach from shore power, turn on the inverter, which only powers a select few outlets, and those outlets all read an 'open ground'. Plug shore power back in, everything is back to normal.

Where is the inverter circuit grounded?

twinboat · 05-11-2019, 05:17 PM

Some aren't.

If it has a transfer ( pass thru ) switch in it, it should bond the neutral to ground when shore power is removed.

Your main ATS should do that when on generator power.

Research your inverter to see if it meets the " UL 458 " specs.

barmcd · 05-11-2019, 05:49 PM

Most coaches don't run all the outlets through the inverter, just a select few. Do you have schematics for your coach? Mine shows the outlets on the inverter.

twinboat · 05-11-2019, 06:54 PM

As a follow up, when on shore power your outlets going thru the inverter are getting 1/2 of a 240 volt service. Line 1 or line 2 + neutral and ground.

Back at the house, the neutral and ground are tied together. That's what the tester is seeing.

When the inverter is creating 120 volts it isn't 1/2 of 240 volts, its just 120 volts between the two wires. Its not hooked to the house.

Many inverters pick one of the wires and call it neutral and tie it to ground only in invert mode. Others don't.

There isn't any chance of a deadly fault to the ground outside, because your not connected to the power grid that uses it.

If your inverter is supposed to be bonded when in invert mode, you need to check the connections down on the inverter for a loose ground connection.

windsorbill · 05-11-2019, 08:38 PM

Quote:

Originally Posted by barmcd

Most coaches don't run all the outlets through the inverter, just a select few. Do you have schematics for your coach? Mine shows the outlets on the inverter.

I don't have a schematic, but I know which are running through the inverter. I labeled them a few years ago.

windsorbill · 05-11-2019, 08:42 PM

Thanks Twinboats for the info. I'll need to dig out the manual.

William Willard · 05-12-2019, 04:12 PM

Bill -- We have owned a 07 Camelot since new --It had a Magnum MSW inverter like yours -- About 8 years ago I installed the Samsung refrigerator -- In doing so, I was checking the inverter circuits & discovered the inverter circuits had an open ground when on the inverter circuits only -- They were OK on generator & shore power--Magnum has a service center here in Gilbert, Az, so I took it to them & the diagnosis was a bad board -- Wanted $700.00 to repair -- So I purchased a Pure Sine Wave inverter & forgot about the repair -- I have no idea how long the inverter was screwed up -- I only checked it on shore power -- Bill Willard

windsorbill · 05-12-2019, 06:10 PM

Quote:

Originally Posted by William Willard

Bill -- We have owned a 07 Camelot since new --It had a Magnum MSW inverter like yours -- About 8 years ago I installed the Samsung refrigerator -- In doing so, I was checking the inverter circuits & discovered the inverter circuits had an open ground when on the inverter circuits only -- They were OK on generator & shore power--Magnum has a service center here in Gilbert, Az, so I took it to them & the diagnosis was a bad board -- Wanted $700.00 to repair -- So I purchased a Pure Sine Wave inverter & forgot about the repair -- I have no idea how long the inverter was screwed up -- I only checked it on shore power -- Bill Willard

Bill,

Interesting. I'm seriously thinking about going to the Samsung. That's what started this thread. I was trying to identify which plug behind the fridge now was on the inverter and which wasn't. That's when I discovered the open ground. Maybe it's normal on this inverter, as Twinboat suggests, I don't know.

Besides an open ground on your old MSW, do you recall what other symptoms you had?

William Willard · 05-12-2019, 06:40 PM

No other symptoms -- In fact, I used the inverter with the open ground after I installed the Samsung for a couple of months --

A side note -- As stated before, we have a 07 Camelot, & when I checked the two recpts in the back of the refer cabinet, neither used inverter power -- A few years later I installed a Samsung in another 07 Camelot -- Neither of those recpts were on inverter power -- Had to do some rewiring -- As the saying goes "Monaco Coaches are like Snowflakes, no two are alike " Bill Willard

Jon_C · 05-12-2019, 08:17 PM

I have an AIMS brand 5000 watt pure sine inverter and it makes 120vac from 2x 60vac. 60v on hot wite and 60v on neutral wire and there can be no neutral to ground bond because of this. ( the 60v on neutral would be dead short to ground) At first I thought it was defective until i called and found thats the way it’s designed to work and it does indeed work well.