Is your stand by gen-set grounded?

Mine is but it lives in an enclosure, it only comes out for me to change the oil in it(on wheels). Mine has a grounding lug on the machine, I bought a copper grounding rod and drove it in the ground, along with one of the copper lugs that fit it. I backfeed my house panel with mine via a lock-out switch in the main panel. I don't think the gen grounding rod does anything but ground the machine itself as mine just feeds my normal house panel, which is double rod grounded per electrical code.
 
Drive 2 -3 ft of rebar into earth and tie to that using the provided GND lug at noted in the OM.. And no I didn't either, but probably should. My gen is on wheels and get moved around. Now that I think of it my house earth is not too good. I have a drilled well pump and that is plastic pipe so no good to tie to water pipes.
 
It's sufficient to connect it to your house ground. Driving a separate ground rod for the generator won't do anything for safety. And if you do drive a separate ground rod for your generator, it has to be connected to your house ground anyway.
 
I have a large 27,000 / 33,000 portable that runs both of my panels. I have a 8awg braded ground from the genset to the house's ufer ground.
 
If you install a separate ground for the generator, you make the generator a separately derived system. If that is the case, the NEC requires that the transfer switch should not only switch the line conductors from utility to generator, but also switch the neutral conductors from utility to generator. If the transfer switch doesn't isolate the neutrals from each other, then the generator should be connected to the same ground that is in use for the utility power. That will eliminate some power gremlins that leave people scratching their heads.
 
ARCOgraphite said:
Drive 2 -3 ft of rebar into earth and tie to that using the provided GND lug at noted in the OM.. And no I didn't either, but probably should. My gen is on wheels and get moved around. Now that I think of it my house earth is not too good. I have a drilled well pump and that is plastic pipe so no good to tie to water pipes.
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Need longer than that. 2-3 feet would never pass any inspection. When the soil dries up in the summer, that 2-3 foot rebar is useless.
 
https://members.rennlist.com/warren/gt5000c.html

If your transfer panel does not switch neutral, the generator should have its neutral conductor floating, not bonded to the chassis. Having a second bonding point will not prevent the system from working. Your lights will come on, but your safety will be jeopardized. If you are going through the expense and effort to purchase and install a backup power system do it properly.

Take a look at return current flow along the neutral and ground conductors. If you have only three conductors, such as with the neutral bond in the main panel and in the generator (or with just a 3-conductor cord), there will be no separate and independant ground conductor bonding the generator frame back to your house ground. There is a potential of the chassis becoming live as there is current flow along the ground conductor.

Remove the neutral bond and now all return current flowing from the live conductors will flow along the neutral conductor only. It will not flow along the ground conductor. This will ensure the chassis remains at the proper potential.

To meet electrical code requirements for stand alone operation, neutral and ground should be bonded together. This can be accomplished quite simply with a standard 120V 15A plug with ground and neutral jumpered and plugged into an outlet. Picture is here. Many of the Chinese built generators with a built in 120/240V selector do some very odd things with the switch. I do not recommend using the neutral/ground jumper plug with those generators.

My personal opinion (and that of others who I have discussed the issue with) is that floating neutral is safer for stand alone operation. Consider having the generator chassis connected to a suitable ground rod. You are a few feet away, standing in a puddle of water with bare feet. Holding one of the live wires in your hand, there is no return path from the neutral conductor or the other live line through the chassis. With no path for current to flow you will not experience an electric shock. If the output uses a GFCI outlet it will not trip. Let's install the neutral / ground bond again and the return current path exists through your feet to the grounded chassis, through the bond jumper to the neutral conductor. You can be assured of a nasty jolt. If there is a GFCI outlet in place it should open. Which situation is safer? In my opinion floating neutral is better, but the electrical code says it should be bonded. It may seem I'm going against my own advice and I won't tell people to go against code requirements, so follow the rules.

Rewiring will likely void any remaining warranty as well as UL/CSA certification of the generator. In my case warranty is not important, and I feel safety has not been jeopardized in any way. In fact the system is safer now than it was originally.

To determine if your generator uses a floating or bonded neutral perform this simple test. With the engine off, use an ohm meter between the chassis and neutral conductors in the outlet. If it indicates open circuit, the neutral is floating. A short circuit will indicate neutral bonded to ground. I don't recommend doing this to household circuits due to the possibility of exposed AC and damage to the meter.

Don't trust the generator label. I've seen many in which it is incorrect. Confirm for yourself either way.
It is normal for to read very low resistance between the neutral and live terminals on the outlets. You are measuring the DC resistance of the output coils.

Plug in an electrical tester as shown and start the engine. If it indicates open neutral, live/neutral reversed, or live/ground reversed do not use the generator and have someone qualified check the wiring and make the necessary repairs. Use the tester throughout your house to ensure it is wired correctly. This sort of tester is often inaccurate for determining whether the neutral is bonded or not. Even with a floating neutral, the second light will often be on. I suspect this is due to very low leakage currents and a high impedance bulb in the tester.
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I have a 5500 watt portable gen. I have driven a grounding rod about 4' deep. I ground to this when operating. For years I did without grounding but with better info I figure better safe than sorry.
 
andyd said:
Should I tie it to my house ground or a separate ground or just fuhgeddaboutit? Does the job fine without it but..
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It's complicated, and depends on how your generator is wired and what type of transfer switch you use. Consult Article 250 of the NEC for detailed info. Also check with your local city or county Building Dept for their interpretation of Article 250.

https://iaeimagazine.org/electrical...nerators-and-electrical-distribution-systems/

https://www.ecmag.com/section/codes-standards/generator-grounding-and-bonding-essentials

https://www.osha.gov/sites/default/files/publications/grounding_port_generator.pdf

https://www.usa-svc.com/PDF/InfoSheets/42.pdf

https://www.electricityforum.com/electrical-training-pdf/electrical-grounding-nec-pdf
One of the most important AND least understood sections of the NEC is the section on Electrical Grounding.

No other section of the National Electrical Code can match Article 250 (Grounding and Bonding) for confusion that leads to misapplication, violation, and misinterpretation. It's generally agreed that the terminology used in Section 250 has been a source for much confusion for industrial, commercial and institutional electricians. Thankfully, this has improved during the last few revisions to Article 250.

Article 250 covers the grounding requirements for providing a path to the earth to reduce overvoltage from lightning, and the bonding requirements for a low-impedance fault current path back to the source of the electrical supply to facilitate the operation of overcurrent devices in the event of a ground fault.
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@andyd Sorry if I missed it, but when you say standby, is this a hardwired, permanently installed gen set? I thought those were built in place with a ground.

In terms of little portables. I've never grounded mine. They pretty much spend their life like this anyway:

fbCKrWKl.jpg
 
Never have grounded my older (stolen) 5Kw clone or my new 9500 Predator. No need, code or safety the way mine is connected.

YOUR application may differ as others have noted and provided advice.
 
If you're talking about a portable generator, and you're using the 240V, four-prong cord to plug into your house, there is absolutely no need to ground the generator. Your house's electrical system is already grounded (it should already have a ground rod(s) or some other kind of buried grounding electrode). The fourth prong on the generator cord is the ground, which connects to the ground bar in the breaker panel, which is also what your house's grounding electrode connects to. Therefore, the generator is already connected to a grounding electrode. Installing another ground rod for the generator is redundant. What you SHOULD do (and what most people fail to do) is separate the neutral/ground bond on the generator, so you don't have neutral current flowing on the ground wire and conductive surfaces of the generator.
 
exranger06 said:
If you're talking about a portable generator, and you're using the 240V, four-prong cord to plug into your house, there is absolutely no need to ground the generator. Your house's electrical system is already grounded (it should already have a ground rod(s) or some other kind of buried grounding electrode). The fourth prong on the generator cord is the ground, which connects to the ground bar in the breaker panel, which is also what your house's grounding electrode connects to. Therefore, the generator is already connected to a grounding electrode. Installing another ground rod for the generator is redundant. What you SHOULD do (and what most people fail to do) is separate the neutral/ground bond on the generator, so you don't have neutral current flowing on the ground wire and conductive surfaces of the generator.
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I was under the impression that the GND was for earthing lightning and static discharge. I was citing from the manual for the GP series Generac roll-away portable units.

here is a photo of the GND statement in the manual.

I will formally give the advice to consult with a Licensed Electrician.

20220311_114436.webp
 
1978elcamino said:
I have a large 27,000 / 33,000 portable that runs both of my panels. I have a 8awg braded ground from the genset to the house's ufer ground.
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Nice! Just curious how far is your humongous genset to the ufer ? My portable is only ~6kw but my ground array is 40 feet way on the other side of the house. Plus the lugs on the rod are loose from the mower hitting them. I tried to tighten them once but got zapped and the meter started spinning faster. The street xformer is 150 feet down the hill from my panel. I did go around the house looking for mis-wired duplex(s), but didnt find any. I didnt look for GND and N tied in boxes.
 
ARCOgraphite said:
Nice! Just curious how far is your humongous genset to the ufer ? My portable is only ~6kw but my ground array is 40 feet way on the other side of the house. Plus the lugs on the rod are loose from the mower hitting them. I tried to tighten them once but got zapped and the meter started spinning faster. The street xformer is 150 feet down the hill from my panel. I did go around the house looking for mis-wired duplex(s), but didnt find any. I didnt look for GND and N tied in boxes.
Click to expand...

The genset has a lug that my ground is attached to. The ground wire to ufer has a clip and I just clip it to the ufer. So, I just roll it out and stretch the ground wire and clip it to the ufer. Not sure if thats what you are looking for but that is how I do it.
 
1978elcamino said:
The genset has a lug that my ground is attached to. The ground wire to ufer has a clip and I just clip it to the ufer. So, I just roll it out and stretch the ground wire and clip it to the ufer. Not sure if thats what you are looking for but that is how I do it.
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I was just curious how long the ground strap was. I also never knew that made a portable with wattage rating over 20kw!
That must be one heavy beast! 750 lbs? Is it a V twin Kawasaki power?
My Generac 5500 does the Well pump, OIl Burner/ boiler, Fridge, TV and some lights
NO electric hot water installed, no dryer usage during outages.
I have noticed bit of surging when the well pump kicks in. Most electronics don't need precise 60hz,
That little thing is a gas hog though.
 
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