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Old 10-16-2020, 09:03 PM   #1
Skoolie
 
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Open AC ground

So I installed 2 120vac outlets in the underbelly storage of my Thomas bus and understand that the campsite 30amp of course has a ground which will power myDC charger and AC unit but my 5000W inverter is used to power my AC outlets in bus and i grounded the inverter to chassis ground along with my Dc charger and DC negative bus bar.the AC output is not grounded and if I using GFI outlets will not work because of open ground. Any workaround for this??
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Old 10-16-2020, 09:59 PM   #2
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When plugged into shoreline, how is the AC "not connected"? Plug tester showing 'open gnd'? If the ground and neutral are separate on the line side (power in from campsite) to your panel, then the panel has a ground and a neutral, assuming you used 3 wire not bx or lampcord, then the load will also be grounded via the copper connection. You only become ungrounded when you separate the copper connection from your bus to the earth (gnd) when unplugged from shore 120v. When connected via tires instead of a grounding rod(s). All campsite recepticals ought to be gfci protected & bonded at the main breaker, ergo grounded. So your gfci should be doing its job even if there are redundant gfcis in-line. If your line side is ungrounded (inverter or shore), #6 copper straight from panel groundbar to earth driven ground rod (2 really). There is only one earth, ground to it via the shortest path. None of this changes how the electrical device will function, but may determine how severe the damage in case of ground fault or overload.
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Old 10-16-2020, 10:01 PM   #3
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Do **not** depend on (your interpretation of) advice from the internet for thistopic.

Get a well recommended professional sparkie to at least look it over, ideally before, but at least after you think everything is safe.
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Old 10-16-2020, 10:13 PM   #4
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Ditto~!
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Old 10-16-2020, 11:40 PM   #5
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Quote:
Originally Posted by Mat7783 View Post
So I installed 2 120vac outlets in the underbelly storage of my Thomas bus and understand that the campsite 30amp of course has a ground which will power myDC charger and AC unit but my 5000W inverter is used to power my AC outlets in bus and i grounded the inverter to chassis ground along with my Dc charger and DC negative bus bar.the AC output is not grounded and if I using GFI outlets will not work because of open ground. Any workaround for this??

Personally, this is an area (AC + semi-complex grounding situation) where I would strongly consider consulting a qualified electrician w/ relevant experience, unless I really felt confident I knew what I was doing.


Based on my shaky understanding of your setup, and my shaky understanding of grounding logic when both shorepower and battery power are options is you want to be using a UL458 listed inverter/charger this switches the neutral-ground bond depending on whether you are hooked up to shorepower or not. An external/standalone automatic transfer switch may or may not provide some or all of the same functionality, this is not something I have looked into at all. I am not sure if this addresses your question in part, but at least it is something to look into. What inverter are you using?
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Old 10-17-2020, 05:44 AM   #6
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at least have a qualified electrician look at it
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Old 10-17-2020, 08:43 AM   #7
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Here's my strategy, oriented toward off grid living, may not be suitable for some.

The **only** source of power for the devices in the living space is the House bank. Those requiring AC power fed by inverter(s) try to minimize these for low consumption efficiency.

Thus, when shore power becomes available, or you fire up the genset,

**only** the powerful charger is connected to it, ideally a "universal world power" compatible version. Both powers the high-current load devices, and recharges the House bank.

Everything on the DC circuits is "grounded" in common, i.e. the usual chassis engine block sense.

The **only** true earth grounding connection is that single cord from the charger to the shore power outlet.

Simple and safe, nothing else has any true earth ground issues to worry about.
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Old 10-17-2020, 08:56 AM   #8
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Thanks for the replies. Let me elaborate a little on this. When I test my two outlets that feed from from my belly storage to bus utility closet, wiring is good with ground. The DC charger 80amps charges my 600AH bank which gives juice for my inverter. The ac output conversion from inverter however is open grounded. I am not using an AC electrical box. Simply converting from inverter to some outlets in bus which I would like to grounded for safety
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Old 10-17-2020, 09:24 AM   #9
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The **only** connection to actual Earth ground (like a 3m copper rod pounded down into moist subsoil) should be

a single connection to shore / grid / mains power.

The data sheet / install manual for the inverter should specify if its metal case should be in common with your vehicle chassis, which is also the common reference for the negative return side of your DC circuits.

There is no other "real ground" in the Earthing sense on a mobile setup with rubber wheels.


Quote:
Originally Posted by Mat7783 View Post
two outlets that feed from my belly storage to bus utility closet
What is the energy source for these circuits, if not your inverter?
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Old 10-17-2020, 07:18 PM   #10
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Originally Posted by john61ct View Post
Do **not** depend on (your interpretation of) advice from the internet for thistopic.

Get a well recommended professional sparkie to at least look it over, ideally before, but at least after you think everything is safe.
Plumbing mistakes can be inconvenient as can carpentry mistakes. Electrical mistakes can be fatal.

I lost two cousins in a fire caused by a DIY electrical project.

Take John's advice.
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Old 10-18-2020, 02:08 AM   #11
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Originally Posted by PNW_Steve View Post
Plumbing mistakes can be inconvenient as can carpentry mistakes. Electrical mistakes can be fatal.

I lost two cousins in a fire caused by a DIY electrical project.

Take John's advice.
I totally agree with that statement, I get a little grumpy when people take shortcuts.
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