Generac Standby Generator Ground Rod

lakee911

Senior Member
Location
Columbus, OH
Before y'all jump in and say that this has been beat to death, look what I found in the install manual of the new 6247 (14KW NG/LP standby Gen). It's a non-SDS.

Generac 6247 Installation Guidelines said:
The National Electrical Code (NEC) requires the frame and external electrically conductive parts of the generator to be connected to an approved
earth ground. Local electrical codes also may require proper grounding of the generator electrical system.
This seems to be new wording over what I've read about in the past. It requires a grounding and grounded conductor run from the house (where they're bonded)
so I'd say that its connected to approved earth ground without the rod.

Has Generac finally gotten this right?
 

A/A Fuel GTX

Senior Member
Location
WI & AZ
Before y'all jump in and say that this has been beat to death, look what I found in the install manual of the new 6247 (14KW NG/LP standby Gen). It's a non-SDS.



This seems to be new wording over what I've read about in the past. It requires a grounding and grounded conductor run from the house (where they're bonded)
so I'd say that its connected to approved earth ground without the rod.

Has Generac finally gotten this right?
I'd say the generator is looked upon like a structure so I think the ground rod is in order and connected to the grounding conductor. Just like a panel in a detached building.
 

lakee911

Senior Member
Location
Columbus, OH
My point was that Generac is no longer requiring the rod "because." They've now modified their requirement and call for it to comply with code. This just moves the ball to, "What is required by code?"

I'd say the generator is looked upon like a structure so I think the ground rod is in order and connected to the grounding conductor. Just like a panel in a detached building.
I'm willing to bet that many folks would disagree with you. Really, though, the NEC leaves the interpretation up to the AHJ because structure is very poorly defined as "That which is built or constructed."

Just curious...those plastic sheds that ready to assemble from the local big box store, are they considered a structure? If one asked you to install a lamp inside and a switch, would you drive a ground rod? (I might consider the ground rod to keep it from simply blowing away :lol:)
 

A/A Fuel GTX

Senior Member
Location
WI & AZ
Just curious...those plastic sheds that ready to assemble from the local big box store, are they considered a structure? If one asked you to install a lamp inside and a switch, would you drive a ground rod? (I might consider the ground rod to keep it from simply blowing away :lol:)
No, 250.32 (A) Exception addresses this.
 

GoldDigger

Moderator
Staff member
My point was that Generac is no longer requiring the rod "because." They've now modified their requirement and call for it to comply with code. This just moves the ball to, "What is required by code?"



I'm willing to bet that many folks would disagree with you. Really, though, the NEC leaves the interpretation up to the AHJ because structure is very poorly defined as "That which is built or constructed."

Just curious...those plastic sheds that ready to assemble from the local big box store, are they considered a structure? If one asked you to install a lamp inside and a switch, would you drive a ground rod? (I might consider the ground rod to keep it from simply blowing away :lol:)
Ground electrode not needed if you run only a single branch circuit to the shed. There should be a breakaway coupling, like on gas pump hoses in case the shed does blow away.
 

lakee911

Senior Member
Location
Columbus, OH
I didn't like the fact that they required it "because" and I'm glad that they have changed the requirement. That's just principal. I've yet to find a good solid reason why it's required by the NEC in an application like this, but I do have one on mine. Can't hurt, right? :) Ok, close thread please!
 

jwelectric

Senior Member
Location
North Carolina
I didn't like the fact that they required it "because" and I'm glad that they have changed the requirement. That's just principal. I've yet to find a good solid reason why it's required by the NEC in an application like this, but I do have one on mine. Can't hurt, right? :) Ok, close thread please!
The best reason can be found in 250.4(A)(1). Just pick one of the four reasons outlined there
 

Daja7

Senior Member
The best reason can be found in 250.4(A)(1). Just pick one of the four reasons outlined there
All of our jurisdictions here have banned the ground rod on the generator. it is bonded throught the service ground back to panel and they are saying that this rod can cause parralell path to ground. not sure but all have done away with it.
 

jwelectric

Senior Member
Location
North Carolina
All of our jurisdictions here have banned the ground rod on the generator. it is bonded throught the service ground back to panel and they are saying that this rod can cause parralell path to ground. not sure but all have done away with it.
If the generator is installed as a SDS then an electrode at the generator would be required by the NEC.

If the generator is installed as a non-SDS then the parallel path would have the resistance of earth and unless there is a low impedance path through earth which would be very unlikely then the amount of parallel current would not matter.

I think that it is a lack of understanding of earth ground that is driving this ban on rods at generators in your area.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
All of our jurisdictions here have banned the ground rod on the generator. it is bonded throught the service ground back to panel and they are saying that this rod can cause parralell path to ground. not sure but all have done away with it.
Grounding electrodes at multiple locations is very common and is not problem assuming that there is only one point of connection between the grounded conductor and the grounding system.
 

kwired

Electron manager
Location
NE Nebraska
All of our jurisdictions here have banned the ground rod on the generator. it is bonded throught the service ground back to panel and they are saying that this rod can cause parralell path to ground. not sure but all have done away with it.
If the generator is installed as a SDS then an electrode at the generator would be required by the NEC.

If the generator is installed as a non-SDS then the parallel path would have the resistance of earth and unless there is a low impedance path through earth which would be very unlikely then the amount of parallel current would not matter.

I think that it is a lack of understanding of earth ground that is driving this ban on rods at generators in your area.
I agree, I would be more concerned over parallel paths through fuel lines, metal raceways, or any other highly conductive paths between the generator and other structure than I would be over any current that travels between the two via a ground rod.
 

lakee911

Senior Member
Location
Columbus, OH
I think that it is a lack of understanding of earth ground that is driving this ban on rods at generators in your area.
Grounding electrodes at multiple locations is very common and is not problem assuming that there is only one point of connection between the grounded conductor and the grounding system.
I agree. Multiple rods are common and even required in some cases. Grounded and grounding conductor should be bonded in one location only. Too many ground rods has never been a problem that I've seen before.

I agree, I would be more concerned over parallel paths through fuel lines, metal raceways, or any other highly conductive paths between the generator and other structure than I would be over any current that travels between the two via a ground rod.
In the case of the Generac residential-grade generators, they're shipped with a flexible rubber gas connector so no additional connection there. Now, in the case of a furnace for example ... yes, one could have a parallel ground through the gas piping (or duct work) assuming it's bonded. The same would apply to a stove too. Even an electric water heater will provide an additional parallel connection. Provided that grounded and grounding conductors are bonded in a single location only, I don't see a big problem and I also don't see how it can be avoided either. Thoughts?
 

Daja7

Senior Member
If the generator is installed as a SDS then an electrode at the generator would be required by the NEC.

If the generator is installed as a non-SDS then the parallel path would have the resistance of earth and unless there is a low impedance path through earth which would be very unlikely then the amount of parallel current would not matter.

I think that it is a lack of understanding of earth ground that is driving this ban on rods at generators in your area.
Could be, if so all seven counties and cities have the same lack of understanding.

either way that is what they want (or don't want) so that is the way we do it.
 
Top