Generator Installation

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samuelrock

samuelrock

Member
Location
Morgan City Louisiana
I have looked through the code for this but cannot make heads or tails,

Option 1

When installing a fixed backup genset should you move the ground from the meter pan to the ATS and then take your 120-0-120 from meter pan to ATS.

at this point your ATS will be your main disconnect and will have a neutral to ground bond. then feed inside with 4-wire and install ground bus bar.

if you do it like this then your neutral will still be connected to the case of the meter pan, thus neutral current can cross over the neutral to ground bond in the ATS and flow across the ATS case to the meter pan and up to the transformer on the pole.


Option 2

I am thinking that maybe you should remove the neutral to ground bond from the ATS and leave the meter pan bonding feed your 120-0-120 to the ATS and then ground your ATS to the #6 comming up from the ground rod with a split bolt.




What option if any is code friendly?
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Welcome to the forum, couple of questions:smile:

1) Is the switch taking over the entire service or just a portion of it?

2) Will the ATS switch the neutral or will the utility neutral and generator neutral always be connected?
 
samuelrock

samuelrock

Member
Location
Morgan City Louisiana
Just a visual....


ATSOPTIONS.bmp
 
H

hillbilly

Senior Member
Question.

Is your Transfer Switch rated for use as Service Equipment?
Does it have a selectable "off" position?

If so, then Option 1 looks good to me, as the Transfer switch will be the Main disconnect.

On option 2, the Main Bonding Jumper is in the wrong place.
It should be located at the first point of disconnect (the Main).

Your last statement about return (neutral) current flowing across the transfer case (Main disconnect) enclosure and back to the bonded meter base and on to POCO transformer is true on any service that's piped in metal conduit and has a meter base that's seperate from the (metal) Main Disconnect enclosure.

Just my opinion
steve
 
samuelrock

samuelrock

Member
Location
Morgan City Louisiana
The ATS is service rated, and has disconnect for generator and POCO so it can be the main disconnect plus it has a bar that can be insearted to put the two transfer coils in the off/open air posisiton.


the thing is, i was at my last job a service electrican for an oil company i worked on ac units and motors and other such equipment. i just picked up a new gig with a generator installation company, they install home stand-by gensets. well in short they were doing it all wrong and it was all getting approved by inspectos, but that still does not mean it was safe.

the first job i went to see them do they pulled the meter base and came off the meter base to the ATS left N-G bond in meter base used metal conduit to the ATS had N-G bond in ATS then they LBed back into the wall and ran 3 wires back into the indoor panel and had N-G bond in the indoor. then as a topper they dropped a second ground rod by the genset and grounded the case of the genset to the ground rod, when keep in mind that the genset is allready grounded to the ATS that is grounded to the main ground rod. the two ground rods were only about 3.5ft apart. This instal had multi parallel paths.

I know from first had that parallel paths can be deadly when i was working on a communication crew a few years back we had one of our guys nearly get killed disconnecting a ground to a data package dish to replace a bad grounding block, the issue was the main house ground had become open and the transformer center tap was loose. when he disconnected the ground from the dish to the ground rod he got the shock of his life!!

I would hate to see one of the guys that go to serivace the genset get shocked due to the installers lack of grounding knolage and failure to follow the code.

This does not just happend at the company i have just went to work for, there are many ac installers and service men that are installing stand-bys and are just installing them by the seat of there pants. in my eyes there is no generator installation in my location that is truely up to code!!

the company now does see that they are installing them wrong as i pointed out some of the code in my 2008, but i am some what at a wash about the best place to put the N-G bond. in my head the best place to put it and where i have allways put it was in the first diconnect as this is the way i was taught to do it so that the ground can be serviced without pulling the meter but now that i am thinking about it i see it is creating a parallel path back to the meter pan due to the center tap going back to the transformer. you can remove the parallel path by installing a PVC fitting inbetween the meter and the first disconnect if the disconnect is mounted out doors, but if you go through a wall to an indoor disconnect you must use metal to go through the wall so you once again have a parallel path. this is where option 2 would come in if you can leave the N-G in the meter pan and then ground your first disconnect to the #6 comming form the rod to the meter pan with a split bolt then your N-G bond would be in the meter pan and you could remove the N-G bond in the first disconnect. now you have no parallel path from disconnect to meter pan and your disconnect is grounded ready to run 4 wires to any sub panel you have.


Let me know whatcha think
 
H

hillbilly

Senior Member
samuelrock said:
but i am some what at a wash about the best place to put the N-G bond.

Let me know whatcha think
Click to expand...


The Main Bonding Jumper must be installed within the enclosure for the Service (Main) Disconnect.

There are few exceptions.

Read 250.24(B).

I can't understand most of your last post..:roll:
Try to use fewer words, and more sentences.:smile:

steve
 
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