Ground showing voltage?

375matt

Re: Ground showing voltage?

I dont see where the ground contacts neutral in switch anywhere?

ChrisOlson

Re: Ground showing voltage?

Don't get confused between mobile applications and your cabin application here. With mobile applications the neutral HAS to be switched when connected to shore power because you are connecting your RV's (or boat's) AC electrical system to a system that has a bonded neutral. This is the first I've hard of a transfer switch here, and what is this transfer switch being used for? Are you switching from inverter power to generator power with it? If so, then your generator must also have a floating neutral, and you stay with a floating neutral in your cabin. In that case it's a simple two-pole transfer switch.

For a switched neutral you will have a three pole switch that disconnects the system neutral from the onboard power source and connects it to the utility neutral. Two totally different applications.
--
Chris

375matt

Re: Ground showing voltage?

I have a pic of it one page back. Im running inverter into transfer switch shore power and generator to transfer switch generator connection then out to my panel. The factory said my inverter has a bonded neutral ground inside inverter n to leave panel floating.

375matt

Re: Ground showing voltage?

My generators are under 3500 watt n have floating neutral I assume.

ChrisOlson

Re: Ground showing voltage?

Well, then I have a misunderstanding because I thought from your first post that this is for an off-grid cabin with standalone power. Now you have shore power to the place? So you are connecting to the utility? And the inverter is bonded neutral? This is a new can of worms.

Firstly, what is the brand and model of this inverter? It needs to be verified that it DOES have a bonded neutral. Can you please try a test for me? Shut the thing down and disconnect the battery power to it. With an ohm meter check for continuity between the neutral blade (the wider of the two slots in a plug) and the inverter frame ground stud.

Edit:
I may have misread your post - I see you are running inverter output to the shore power input on the transfer switch.

Could you check BOTH your generator and inverter for bonded neutrals for me? Both are checked in the same way, as noted above.
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Chris

BB.

Re: Ground showing voltage?

You only need to switch "two poles" if you have a 120 VAC system and want/need to switch Black and White wires (aka hot and neutral).

If you have 120/240 VAC splt phase--Then you need to switch Black/Red/White for a "complete" neutral switching circuit (i.e., neutral supplied by genset switching to neutral provided by inverter).

Be really clear on the use of the term "neutral" with MSW inverters (and generators)... They don't all mean the same thing, or they don't even talk about it in the manuals.

-Bill

375matt

Re: Ground showing voltage?

It is a vanner bravo 2600 sh with no charger .

When i set the meter to the beeping continuity test i get a beep from the ground lug to the wide neutral blade.
I also get one from the ground to the hot small blade.
Also get a beep from neutral to hot.

Here is an email from manufacturer:
Hi Mathew,
Yes neutral & ground are tied together inside the inverter. Neutral & ground
should be isolated in your distribution panel.
Thanks,

375matt

Re: Ground showing voltage?

Generator is a eg2200x honda. No beep from neutral to ground on generator outlet.
Beep from hot to neutral on gen outlet.
Beep from gen outlet ground to frame

ChrisOlson

Re: Ground showing voltage?

It took me a little bit to find the specs on that inverter. It does indeed have an internal neutral ground bond. Which means, as they told you, neutral and ground remains separate in the service panel. And you wire it just like a house - GFCI and single pole breakers and switches all work as normal. However, because of the MSW, you may experience some buzz in GFCI transformers.

However, the inverter becomes the utility transformer or service entrance (in NEC parlance) because it has the neutral ground bond. You can not have another neutral ground bond in the system anywhere. So your generator is fine, you put neutral on the neutral bus in the box, and hot to the hot buses. You must install a separate ground bar for the grounds in that box.

In your transfer switch neutral is pass-thru from the generator to the system neutral and MUST be connected to the inverter neutral in order for the bonding to remain in effect. So you only switch the hot wire in the transfer switch.

For grounding, you drive a ground rod for the inverter and the inverter's grounding lug is connected to it. This is your earth ground. Battery bank ground is also connected to that same ground rod with a separate wire and clamp on the ground rod. Do not drive a ground rod for the generator. The generator frame is connected to system ground thru the grounding pin when it's connected to the system.

You should be fully wired to code with that setup, as far as neutrals and grounding goes. The reason you were seeing a small amount of voltage is due to leakage and the fact that the unit was not grounded properly. There should be no potential (voltage difference) between grounds. Connecting BOTH DC and AC grounds to the common grounding point insures that potential does not exist between them.
--
Chris

375matt

Re: Ground showing voltage?

Thanks, Normal house wiring to code sounds good to me!

So on the transfer switch I tie the 3 neutrals together from the inverter, generator and panel and only switch between the generator hot and inverter hot black wires?

Just so Im clear on the grounds... Ground rod to inverter ground lug then do i need to bond all the other ground lugs to this wire for ioata 55 charger, power max transfer switch, square d distribution panel, xantrex xw mppt 60 charge contoller, battery bank negative post.

You mention i can not have another neutral ground bond anywhere. I have it all temporarily grounded to my home grounding rod. Is this an issue?

Does any of this change how i ground my xantrex xw 60 mppt cc? It has that gf bypass option thats confusing me a bit.

ChrisOlson

Re: Ground showing voltage?

All those grounds go to the same ground rod, regardless of how they get there. Typically there will be a grounding bar in your service panel where the ground connections from circuits and components will be made. Once the inverter frame or ground stud is connected to the ground rod, there are three wires that come from the inverter to feed the distribution panel (hot, neutral and ground). That ground from the inverter provides the ground path to the ground rod for that panel. And so on.

There will typically only be two large bare copper wires going to the ground rod for an off-grid power system - one from the inverter or service entrance panel (which ever has the neutral/ground bond made in it), and the other from the battery bank negative bus bar.

Having your test setup connected to your home ground rod is no issue at all.

It's really nice that you got a DECENT MSW inverter. Looking over the specs on that unit, it looks fairly robust.
--
Chris

375matt

Re: Ground showing voltage?

Glad to hear it's a decent inverter. It was given to me and came out of a fire truck. I doubt it was ever used. I think that brand is popular in emergency services?

ChrisOlson

Re: Ground showing voltage?

I found several references to them being used in ambulances. Usually stuff that is used in ambulances is not junk.
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Chris