Grounding generator

Status
Not open for further replies.
T

tromtommyt

New member
I have a 14kw generac generator air cooled. the manufactures instructions state to drive a ground rod next to the generator and attach to lug provided on the generator frame. the netural is not switched in the transfer switch and the ground and the netural are seperated at the generator all the way back to the main service. should i drive a ground rod at the generator and connect to the lug on the frame.
 
raider1

raider1

Senior Member
Staff member
Location
Logan, Utah
Welcome to the forum.:)

110.3(B) requires that the installation instructions included with the listing and labeling be followed.

With that said, driving a ground rod and connecting it to the frame of the generator will not accomplish much. It is most likely a CYA from the generator manufacturer.

Chris
 
V

vinster888

Senior Member
Location
Nature Coast of Florida
raider1 said:
Welcome to the forum.:)

110.3(B) requires that the installation instructions included with the listing and labeling be followed.

With that said, driving a ground rod and connecting it to the frame of the generator will not accomplish much. It is most likely a CYA from the generator manufacturer.

Chris
Click to expand...

thats exactly what that is. and when yo dont install it, it is there way of getting out of some warranty issues
damned if you do and damned if you dont. i dont
 
tom baker

tom baker

First Chief Moderator
Staff member
Location
Bremerton, Washington
I went to a Siemens seminar on generators, they sell rebranded Generacs. I asked why they require ground rods at generators that are not seperately derived and they said the inspectors require them, so they require them. I was upset that Siemens is rolling over on this and taking the easy way out. The Cummins generator I installed had very clear instructions on how to ground it, depending on the transfer switch used, 3 pole or 4 pole.
 
raider1

raider1

Senior Member
Staff member
Location
Logan, Utah
Corey Zachel said:
inspectors treat it as a seperate system and dont want it tied to the building ground. NEC 250.30.
Click to expand...

95% to 99% of the time the generator is NOT a separately derived system. Unless the neutral is switched in the transfer switch the generator is not going to be a separately derived system. The inspectors should be able to understand this principal and only treat the generator as a SDS when it is actually being installed as one.

Chris
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
from this thread:
http://forums.mikeholt.com/showthread.php?t=107490&highlight=generac

I discussed this with Generac a few months ago.
Their engineer advised GENERAC does require a ground rod.... factory requirement.. check the install manual.

according to him (not me) .. the design of their system will detect a "ground fault" on the line side of their disconnecting means and shut down the generator provided this goroud rod is installed...

their engineer still insists the Generac required gournd provides a type of "internal protection". Bogus or not, that was their verdict.
 
chris kennedy

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
Corey Zachel said:
inspectors treat it as a seperate system and dont want it tied to the building ground. NEC 250.30.
Click to expand...

You may want to politely point this out to the inspectors in your area.

Separately Derived System.
A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct electrical connection, including a solidly connected grounded circuit conductor, to supply conductors originating in another system.
Click to expand...
 
raider1

raider1

Senior Member
Staff member
Location
Logan, Utah
Corey Zachel said:
sorry, we only do neutral switched systems for standby generation. dont want to mislead. thanks for clarifying fellas.
Click to expand...

No problem.:)

May I ask why you use a switched neutral for standby generation?

Also by standby do you mean optional standby or legally required standby?

Chris
 
C

Corey Zachel

Member
Location
Northwest Ohio
backup only, not required. mostly for food service, tech equipment ups's, lighting, etc.

My boss wrote the spec and wants it adhered to. I dont know that I have ever raised a fuss as to why. I dont see anything in NEC that states when to and not to. Can you shed some light on standard practice. I don't doubt that I may learn something.
 
raider1

raider1

Senior Member
Staff member
Location
Logan, Utah
It is a design issue as to whether or not to install a generator as a separately derived system.

I don't think that I have ever installed a generator with a switched neutral. It is simpler to not treat the generator as a separately derived system and just keep the neutrals and equipment grounds separate.

Chris
 
R

R Bob

Senior Member
Location
Chantilly, VA
LarryFine said:
Tommy, welcome to the forum! :smile:

I always drive one per Generac.
Click to expand...

I always drive one no matter who the mfgr. is or what thier instructions say.

I installed a 15K B&S for a propane gas company. (That's right...even propane gas companies are selling generators now!)

The instructions did not explicitly require a ground rod. So I didn't drive one.

The inspector wanted me to drive one.

I questioned his reasoning, pointing out that it was not an SDS and the mfgr's instructions did not specify a ground rod.

He said that it had nothing to do with with either point I made, it was for lightning protection.:-?

I give up...every genset gets a ground rod!
 
C

Corey Zachel

Member
Location
Northwest Ohio
I am going to dig deeper and find out when to use what. I'll post when I know. I more want to know what my boss wont teach me or better if he's wrong and doesn't know it.:grin:
 
raider1

raider1

Senior Member
Staff member
Location
Logan, Utah
He said that it had nothing to do with with either point I made, it was for lightning protection.
Click to expand...

Then you asking the inspector where lightning protection is require by the code.:rolleyes:

Chris
 
Status
Not open for further replies.
Top