Magnum Inverter

[William Willard]

We have a 07 Camelot with the ME 2012 Magnum Inverter -- Purchased this M/H new, but have used the inverted for 110 power twice for short periods -- Recently I checked the 110 recepts to see which was powered by the inverter -- The recepts showed OPEN GROUND (no ground detected) on both circuits, but good on both shore, & generator -- This test was conducted using 3 different testers -- The grounds are bonded & a tight connection on the inverter lug -- No satisfaction from Magnum tech support -- Is this a common problem, & have you checked for correct wiring of your recepts -- Anyone have a suggestion for a fix? --- William Willard

[pcarrell]

William; Do you have a subpanel that has the inverter one and inverter two breakers in it. If so check and see the voltage with the inverter off should be 0. Then turn the inverter on and see what your voltage is. You will also have to have a True RMS multimeter to check inverter voltage if it is a modified sine wave. My inverter voltage was showing 98 volts with my 3 VOMs. I got a Fluke meter that measures true RMS and I had 120 volts. You could be showing an open ground because of this.

[William Willard]

pcarrell-- No subpanel -- The ME2012 inverter has the two, 20amp, pop-out breakers in the case -- Bill Willard

[azstork]

Bill - After reading your post I went out to see what my RV does on inverter power - I have the Magnum ME2012 as well. I disconnected the shore power cord, turned on the inverter and checked the outlets with a "plug-in 3 light tester" which will show reversed polarity open hot, open ground, etc. Aside from the outlets in the BR slide and in the Dining wall which are not on the inverter, all of the outlets tested normal, no open ground. Hope this helps.

[pcarrell]

William; I don't know where you would check. The inverter would have to be grounded. Do your plugs ins coffee pot, alarm clock, work when you are on the inverter? Seems if the circuits are ground on shorepower they would be grounded on the inverter. I will check with a friend of mine and see if he has any ideas.

[William Willard]

I used the 3 light tester also -- Everything works on inverter power, but a ground is not nessary to have power --The GFI in the bathroom will not break on inverter, but will on shore/gen power -- Bill

[azstork]

I checked my bathroom GFCI outlet and like yours, it works on shore power but will not break the circuit while on the inverter, even though my tester shows an "intact ground" based on the idiot light. So I would assume we are not protected from a bad appliance, hairdryer or cord while on the inverter. Maybe someone with more electrical knowledge on the forum can explain it to us...perhaps the neutral and ground are tied together on inverter power and the GFCI can't detect leakage current since there wouldn't be any?? But that wouldn't explain why your rig is showing an open ground.

[Robi.1014]

WW: You're caught in a temporal void. Oops... wrong TV show.

Seriously,
Boat and RV wiring standards call for the ground lead and the neutral (white) lead to be joined only at the most distant source of electrical power. When using shore-power in your RV, that ground/neutral joining is supposed to occur at the power pole of the RV site. When the Automated Transfer Switch (ATS) activates (because you're running the generator), the ground/neutral joining occurs inside the generator. The ATS switches all 3 leads (ground, neutral-white and hot-black) to shore power or genset power. Stated another way, the ATS is a 3-pole switch.

I guess you're aware that the Inverter is somewhat similar to a ATS. If the Inverter is turned on, it "looks" to see if there is a source of AC power at its input (be it shore or genset -sourced power). If the Inverter detects no AC at its input, then it switches mode and outputs its own AC power (thanks to your house battery-bank). OK. So you know all this. What's the point? Well, the Inverter's internal "switch" (that I just mentioned) is indicating that it is a 2-pole switch...or perhaps only a one pole switch (more later). As you say, the ground wire is bonded and/or connected to a lug on the Inverter's housing. Buuuuuttt: There is no ground/neutral connection made within the Inverter when the Inverter is, well, inverting.

So where should the ground come from? If I give you an answer here, I'll take grief from at least 50% of the boating/RV-ing population.

What I would have you do for now is remove the cover on the Inverter where the AC comes in and goes out. These terminals are typically well labeled as to what should be connected to them (using words like "white" or "neutral", etc. ... rather than just "T1" and "T2"). Please take a look at these and let this forum know what you found. Then I'll offer you my opinion!!

[Robi.1014]

and.... in the 50-amp world, the ATS is a 4-pole switch.

[William Willard]

Robi.1014 -- The 10 gauge in wire -- Ground to ground lug with the 2 circuits out grounds, bonded to it --- White wire to neutral lug -- Black wire to -- HOT 1 IN -- Jumper from HOT 1 IN to HOT 2 IN --- GFI out circuit -- Black wire to HOT 1 OUT --- Microwave out circuit --- Black wire to HOT 2 OUT ---- Both White wires to neutral lug --
Checked the main panel box, & the converter circuit is wired correct -- Like all RV`s, it has a buss bar for the neutrals & a bar for the grounds -- In the converter, I can get a circuit, when on shore/gen when I go hot to ground on all circuits, but on inverter, that is not the case --
The reason I checked the inverter, was I wanted to run a circuit to the refer area, in case I wanted to install a resdential refer, that`s when I discovered the open ground -- Checked with another RV`er with the a simuliar coach, & he had hot,netural reversed -- We don`t dry camp, so the inverter was seldom used -- Bill

[RJay]

William,
Robi.1014 is on the right track. When the inverter is switched on and there is no other source of AC the inverter connects its ground/bond thru a relay. This is so there is only one ground/bond connected to the RV in at one time. If either the generator or shore power is connected/available the relay opens and removes the ground and turns off the inverter. I'm not specifically familiar with your brand of inverter but it could be you have a problem with this relay or a loose ground/bond wire in the inverter.

[Robi.1014]

Bill,

I'm onboard with what RJay wrote. My guess is that the relay (the 2-pole device I was writing about) actually has a 3rd pole that switches ("shunts") the house white/neutral wiring to the ground-buss inside the Inverter when the Inverter is producing juice. But this isn't happening due to a contact failure (of the 3rd pole) or loose/faulty wiring within the Inverter.

When the Inverter is not supplying inverted power, your neutrals and grounds are shunted at their proper location: at the RV-site power-pole or inside your genset (when running).

[William Willard]

Thanks all for your response -- Have the answer to the problem, now where do I find the part for the fix? Bill Willard

[Robi.1014]

Well, if we've diagnosed this correctly, what is failing is internal to the Magnum. They would probably be your source for replacement(s). But if I were a betting man, I'd say that something is mis-wired within...and that the relay is OK. So are you "going in" ???