6k inverter putting current through mounting bolts

It is grounded by a 4/0 wire and the most watts it has seen is from my 1500 watt microwave.

This would likely have to be a grounding issue with the external system; I do not see any way that the inverter itself could be energizing the case.

The only internal connection to the chassis should be just a little 12AWG wire connected to AC Output Neutral through a 10nF decoupling cap (Rev. B and C).  This won't pass much of any power; it's there for UL requirements that the chassis should basically be "centered" to the AC output potential.

You can try looking through the side grilles to make sure that none of the transformer primaries are touching the chassis--but even if they were, they could not put a potential through the chassis mounting bolts (as the transformer is isolated between primary->secondary).

Now, if you can rule out external grounding as being a fault, and the underside of the inverter chassis is very hot (but not the sides of the case), there's a chance the transformer bolt insulator is broken--or something's amiss in that general area.

Another possible issue would be if the inverter is bolted down to a metal surface, and the head of the transformer bolt (on the underside of the inverter) is in contact with said metal.  That will create a very high heat zone across the underside of the inverter; it can be very dangerous (and worst part is that it doesn't increase no-load draw very much!) 

Worth noting that on the redesigned GS inverters, I moved the insulator to the inside of the inverter...completely solving this potential issue.

Is the case bonded to the negative terminal? I'm thinking it's possible my cab to chassis ground may be faulty and it's using the inverter as a ground path.

It is on a rubber mat with half inch cotton batt insulation underneath.  Only place the case is in contact with metal is the self tapping bolts.

Is the case bonded to the negative terminal?

The battery dc  negative should not touch the case .   The AC ground  is bonded to the  case .    RV chassis ground  is not ground for the  inverter .    Be careful  of RV  grounding   and most RV  has GFCI  to be safe .    

No.  Like I said above, the ONLY internal connection to the chassis SHOULD be to AC Output Neutral through a 10nF (0.01uF) capacitor.

I don't see how DC Negative could get shorted to the case, as the negative wires go from the battery terminals to between the heatsinks.

Check and see if the underside of the case (or as close as you can get to the foot) is hot with the inverter at idle.  That'd let us know pretty quick if the transformer bolt is at fault; worth noting, we are not aware of a single center transformer bolt isolation failure on a GS inverter--but that's not to say it can't happen.

I was thinking of the same thing there may be a shunt involved as well.  Maybe pull the mounting screws out and check the case to ground with a meter to see if its a high voltage or low voltage issue. 

Seems to be getting some ac bleed onto the case. I took the mou ting bolts out and went to lift the case up to feel underneath of it. All I can relate it to is the feeling of a low voltage current flowing though my hand. Enough to tingle but not enough to hurt.

Which there will be.  You'll feel the 10nF decoupling cap...

...I think you need to break out a meter and start measuring potentials (try both AC and DC) to figure out what's going on.

I would expect the following readings from the case to the AC output terminals (assuming your unit is 240v split phase output; if not, half the numbers here):

• L1: ~120vAC
• N: 0vAC
• L2: ~120vAC

And to the battery terminals, I would similarly expect about 120vAC to either.

Any notable DC potential (>3v) would indicate other issues--but this is way too low to be felt.

L1 to case: 140.7VAC steady

L2 to case: 143.4VAC climbing to 159.8 before dropping to 143.4 and repeating.

N to case: 20VAC dropping to 17 before jumping back to 20 and repeating.

Similar readings to the negative terminal with the exception of L2 which is 105VAC to the negative terminal.

Check and see if the underside of the case (or as close as you can get to the foot) is hot with the inverter at idle.  That'd let us know pretty quick if the transformer bolt is at fault; worth noting, we are not aware of a single center transformer bolt isolation failure on a GS inverter--but that's not to say it can't happen.

You can also measure AC voltage from the transformer bolt to the case; it should be ~1vAC.

Better option on the center bolt

Weld the nut to the strap and have the bolt be for shipping only

It won't be needed for support on an installed unit

Has no electrical function

Prevents critical air flow through the center of the transformer (the hottest part)

That's an idea for sure...but there's 2 challenges presented by the "fully GS designed" upcoming units:

• The transformer bolt is now a carriage bolt.  Removal of said bolt would require opening the case, as there's no external head on the bolt anymore!
• Fans now blow from the side, not from the top.
  • additionally, I personally experimented with having a fan blow air directly through the center of a toroid transformer--and it did not increase the wattage capability by any significant amount.  This could be explained by the much smaller surface area of the inside of the toroid vs the outside: the more surface area, the easier it is to dissipate heat.

The outside will offer allot more surface area but the center will be much hotter

Really it needs to have flow on both

It may not effect it's capability all that much but it does help and isn't that hard to do

Consider a strap that has a ring in the center with 4 legs coming off it

It clamps across the top of the transformer and tight to the sides but not the center

The center bolt design acts as a thermos by  having an enclosed air space

It also eliminates the loop effect of the clamp (mitigated by the bolt insulator