Home generator grounding

Status
Not open for further replies.
C

coppernec

Member
I seem to get different answers for the need to put a seperate copper ground stake in on a 120/240 home generator system. Some have said you must install an 8 foot 5/8 copper stake. Others say if the generator is grounded through wiring to the home, ( which they are ) you would be creating a ground loop.
What is the correct way for this application.
Thank you for your response,
Keith
 
It depends on how loads within the house are connected to the generator. If all you do is plug extension cords into receptacles built into the generator, then you don't need a ground rod. If you are connecting the generator to the home wiring system (as it sounds like you are doing), then you do need a ground rod. The reference is NEC article 250.34.
 
So even though utility ( com ed ) provides grounding protection, we still need another ground rod? If so doesn't that create a ground loop?
 
I did not mention that the generator has a ground wire that goes to the auto transfer switch which is grounded to panel
 
charlie, would that not depend on the generator being a SDS or not ??
If the generator is not a SDS (neutarl unswitched) and is connectd to the building equipment ground is there a requiremnt for a ground rod ?
 
I am confused as to whether we are talking about portable generators, stored in the garage and brought out when needed, or permanently mounted and permanently wired to an ATS. The rules are different, I believe.
 
augie47 said:
charlie, would that not depend on the generator being a SDS or not ??
If the generator is not a SDS (neutarl unswitched) and is connectd to the building equipment ground is there a requiremnt for a ground rod ?
Click to expand...

If the generator sits on a foundation, it needs a seperate rod.It would be a seperate structure.
Rick
 
RUWired said:
If the generator sits on a foundation, it needs a seperate rod.It would be a seperate structure.
Rick
Click to expand...

Separate structures SUPPLIED by the house would require a grounding electrode system.

Generators are not supplied by the house, hence that requirement is not applicable.

The reason for the installation of the ground rod at the generator is 110.3(B).
 
Pierre C Belarge said:
Generators are not supplied by the house, hence that requirement is not applicable.

The reason for the installation of the ground rod at the generator is 110.3(B).
Click to expand...

So your saying the manufacturer requires it? What about the battery charger and block heater being served by the house. Would that qualify?


While reaching for a bowl of cereal it hit me that as long as if its a single branch it does'nt need.
Rick
 
Last edited:
If you are still connected to the utility neutral (non SDS) then you do not need a ground rod.
Guardian/Generac requires a ground rod for lightning "protection".
Some AHJs want it, others may make you disconnect it.
 
coppernec said:
So even though utility ( com ed ) provides grounding protection, we still need another ground rod? If so doesn't that create a ground loop?
Click to expand...
It's not considered a loop if the earth is part of the path. That's why the old rule allows (soon to be 'allowed') a grounded neutral (i.e., a 3-wire feeder) in a separate building as long as there is no other conductive pathway between buildings; that would be a loop.
 
I am still not clear, I seem to be getting different answers. This is an Automatic start and automatic transfer unit. The generator sits outside permanently, sometimes it sits on a preformed concrete slab, sometimes on a Polly slab over some pea gravel. It has a ground wire from the generator to the transfer switch and to the panel which is grounded to utility ground.
 
Are the transfer switches two pole or three pole? (does the ATS switch the neutral or is it a solid connection?)

Roger
 
Home Generator grounding

Home Generator grounding

augie47 said:
charlie, would that not depend on the generator being a SDS or not ??
If the generator is not a SDS (neutral unswitched) and is connectd to the building equipment ground is there a requiremnt for a ground rod ?
Click to expand...

I agree. If it is a SDS it needs to have a grounding electrode system,if the ats does not switch the neutral it does not need to be grounded, but must have a egc.
 
Every stationary generator I have installed came euipped with an external grounding lug, and I have used solid #6cu to bond every one to a driven rod, either an existing one or one I drove.

The "ground loops" we need to avoid making are those that interconnect neutral conductors, not EGC's and GEC's. The neutral is not bonded in most generators, so electrodes aren't a problem.
 
LarryFine said:
Every stationary generator I have installed came euipped with an external grounding lug, and I have used solid #6cu to bond every one to a driven rod, either an existing one or one I drove.
Click to expand...

Larry there is no reason to do that unless the transfer equipment switches the grounded conductor as well as the ungrounded conductors.
 
Home generator grounding

iwire said:
Larry there is no reason to do that unless the transfer equipment switches the grounded conductor as well as the ungrounded conductors.
Click to expand...

Here I go agreeing again (only because it is true)
 
iwire said:
Larry there is no reason to do that unless the transfer equipment switches the grounded conductor as well as the ungrounded conductors.
Click to expand...

Unless the specs calls for it.We've been installing 4/0 cu. around the foundation with 4 rods , 2 to the rebar matts 1 to the frame 1 to the gen terminals ground bar 1 for the house panel.All that for non SDS.
 
Status
Not open for further replies.
Top