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Author Topic: Grounding a portable generator  (Read 6646 times)

John From Detroit

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Re: Grounding a portable generator
« Reply #30 on: September 04, 2018, 07:09:59 AM »
When deploying any of our mobile surgical facilities with dual 150KW generators the first thing that we do is to drive a 6 foot copper grounding rod into the earth as a safety factor.

Grounding is required... if I recall correctly (Please do not take my word for the number) on Generators over 50KW.. but as I stress I may be off on the KW
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rvwanderer1

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Re: Grounding a portable generator
« Reply #31 on: September 21, 2018, 11:04:56 AM »
I used a portable generator in a sailboat.  Never grounded it.  never had a problem.  Grounding in a sailboat usually means running a heavy wire and attaching it to the metal keel bolts.
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2floating

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Re: Grounding a portable generator
« Reply #32 on: October 16, 2019, 04:54:39 AM »
Actually the big thing to avoid is something you have not mentioned. That is the neutral-ground bond. In a typical AC system, there is a "bond" between the white neutral wire and the bare(or green) ground wire made in the AC load distribution center. There should only be one bond in the system. The problem comes in when a generator is introduced. There is no industry-wide standard whether or not the generator shall or shall not have the generator neutral and ground wires bonded within the generator.

You should examine the wiring schematics for each piece of equipment to ascertain if they have an internal neutral-ground bond.

Often portable generators (Mod note: affiliate link removed) with chassis-mounted receptacles have internal bonds. It's best to have the neutral-ground bond at the main AC panel, so bonds in equipment must be removed.

The same neutral-ground problem can arise with an inverter; some bond and some do not.

Grounding is best accomplished by driving an 8 ft copper-clad rod into the ground and connecting that to a ground block or bus using a single #6 copper wire. Then each piece of equipment is connected to that ground block. This would include a charge controller if/when PV modules are introduced to the system. There is nothing wrong with having a second ground rod in the system. If there is a second ground rod it should be connected to the first ground rod with #6 wire. The second rod should not connect to the ground block/bus or to any other piece of equipment. A second ground rod is actually required if you wanted to check the efficacy of the grounding system. With two rods there should be a minimum ten-foot separation.

The DC side of the system should also have a neutral-ground bond and there should be a ground rod as well. The NEC does not require a ground rod in a 12 VDC system, but it is a good idea nevertheless.

Is that grey box between the generator and the inverter/charger a transfer switch? Or does the inverter have an internal transfer switch? If the inverter/charger does not have an internal transfer switch there should be a transfer switch. The generator connects to one input side. The inverter/charger AC output connects to the other input side. The transfer switch output then connects to the AC load/distribution center. That way only one source of AC can be feeding the cabin AC system at a time. No danger of mix-ups.
« Last Edit: October 16, 2019, 11:44:23 AM by Back2PA »
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IBTripping

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Re: Grounding a portable generator
« Reply #33 on: October 17, 2019, 08:38:30 PM »

There is a simple and inexpensive way to do this, and it requires no skills or modifications to the generator.  Buy one of these and plug it into one outlet of your generator.

https://www.microair.net/products/generator-bonding-plug?variant=12272654155860

Also, here's a link to a lower cost grounding bond plug on Amazon: https://smile.amazon.com/Southwire-Company-LLC-44400-Generator/dp/B07F4R7BDL/ref=sr_1_fkmr1_1?keywords=generator+ground+bonding+adapter&qid=1571362444&sr=8-1-fkmr1

Reviewers say it works fine on RVs.

P.S. Love your irony "Optimistic Paranoid"  ;D ;D ;D ::)
« Last Edit: October 17, 2019, 08:40:25 PM by IBTripping »
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cavie

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Re: Grounding a portable generator
« Reply #34 on: October 27, 2019, 05:28:40 AM »
Wow, that is amazing. The manual states to ground it so the GFIs work properly? Ground has absolutely nothing to do with the operation of a GFI. A GFI measures the amperage of the neutral and the amperage of the hot wires. If they are identical then it allows the current to keep on moving. If there is a leak and therefore a mismatch of around 5 milliamps then it trips the circuit in less than 1/30th of a second. That leaked current is going to ground, but there is no ground wire in the circuit. The leaked current is going to ground either through an alternate path, such as water or a human being. The beauty of a GFI is the speed at which it detects the ground fault and trips the breaker. The fellow who invented the GFI gave a public demonstration to prove the worth of the GFI by holding a radio that was plugged into a GFI outlet and jumped into a bathtub full of water. He lived and every new building constructed since then is protected by GFIs.

Ground has everything to do with a GFI but I'm not going to get into it here. It's described pretty good already in the thread by Gary RV_ Wizard if you care to read about it.  Retired 50 year Master electrician.
« Last Edit: October 27, 2019, 05:34:04 AM by cavie »
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SeilerBird

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Re: Grounding a portable generator
« Reply #35 on: October 27, 2019, 05:43:22 AM »
Ground has everything to do with a GFI but I'm not going to get into it here. It's described pretty good already in the thread by Gary RV_ Wizard if you care to read about it.  Retired 50 year Master electrician.
How did you ever become a 'master' electrician? Gary did not describe any need for a ground for a GFI. Here is what he said:

Quote
That leaves the question of what does "ground" mean on a portable genset.  It has nothing to do with GFCI (see Seilerbird's reply). The ground wire pin on a portable genset is bonded only to the generator frame.
A ground wire has absolutely nothing to do with a GFI. It is totally unnecessary. They work just fine without one. The proof of that is in any RV that is off the grid running on an inverter or a generator the GFI works just fine and there is no ground anywhere. If the ground was necessary then the GFI would not work. The reason you are not going to get into it here is because you can't. I am a retired 52 year UNION electrician. In the union you actually have to go through an apprenticeship and learn how electricity actually works.

cavie

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Re: Grounding a portable generator
« Reply #36 on: October 27, 2019, 06:52:46 AM »
How did you ever become a 'master' electrician? Gary did not describe any need for a ground for a GFI. Here is what he said:
 A ground wire has absolutely nothing to do with a GFI. It is totally unnecessary. They work just fine without one. The proof of that is in any RV that is off the grid running on an inverter or a generator the GFI works just fine and there is no ground anywhere. If the ground was necessary then the GFI would not work. The reason you are not going to get into it here is because you can't. I am a retired 52 year UNION electrician. In the union you actually have to go through an apprenticeship and learn how electricity actually works.

I am very aware of how a GFI works. I have installed many on two wire systems.

It amazing to me how an Edison plug with the neutral and ground tied together and plunged into a portable generator  will solve RV, GFI, and Generator problems. Many RV's will not work without this if you do some research.

The be a Master Electrician I to have to learn the be an electrician. ( been doing that for 50 years) I also must also take hours long test ( forgot how many. About 6 as I can recall. 35 years ago.) to get a License to own the two business I have.  Have a nice day. :) I'm done here.
Retired Licensed Master Electrician/Electric inspector
All Motor Homes are RV's. All RV's are not Motor Homes.