If you recall, a few months ago I began a project of re-wiring a dairy barn for conversion into a shop. At that time, I followed all advice given me from this forum. My farm house main panel will be supplying the remote dairy barn with a 100 amp breaker. There will be a 100 amp service disconnect box mounted on the outside of the dairy barn. I was instructed to make sure the jumper (green screw) was disconnected so that the neutral and ground were seperated and not bonded. Since this was not possible with the service disconnect box purchased, I purchased a seperate, insulated grounding terminal from Grainger, which is capable of receiving the #6 ground. This insulated grounding terminal will be mounted seperately, in an insulated fashion, using sheet metal retention screws inside the service disconnect box. At this point, the ground and neutral will have been isolated. From the service disconnect, the 3-#2 THHN/THWN w/ #6 Ground will proceed into the dairy barn to the sub-panel. Currently, there is a 125 amp main breaker in that particular sub-panel box that will be changed out to a 100 amp breaker. The Sub-panel box will have approximately 3 220 circuit breakers and 4 110 circuit breakers. My question is: In the SUB-PANEL box located inside the dairy barn, should not the neutral and ground buss bars be bonded, as in a main panel box inside the farm house? Was it sufficient to seperate them only in the service disconnect box located outside of the dairy barn? I noticed that there was a similar question earlier in the forum, and it appeared similar to my question, except that they did not have the service disconnect box.

 

they should be seperate again,,, but I am curious as to how you bought a panel that couldnt be unbonded,, was it listed as service entrance equipment only? The only place they should ever be bonded is at entrance in a 4 wire system.

 

The grounding terminal that you purchased should not be insulated from the box. Also, sheetmetal screws are not listed for grounding. Your ground bar should look similar to this.This one is G.E.. Notice that it comes with mounting screws that fit threaded holes that are already in the panel. About $5 at the big box stores.

 

I may have confused things, but the ground block that I have purchased for the OUTSIDE Service Disconnect box only has a 100 amp breaker encased in it, with no room for any other breaker. In actuality, the ground block that was purchased seperately is actually a Bussman 5A672, which is actually a Power Distribution Terminal. The reason for the purchase is to allow adequate number of large tie-ins for all needed #6 Ground wires. All three poles will be bonded on one side. One large side pole will be for the incoming ground from the farm house, the next pole will be for out-going ground to the Dairy Barn Sub-breaker panel thru tubing, The third pole will be out-going thru the bottom of the service disconnect to the two seperate but bonded ground rods, seperated by 10 feet. #6 THHN/THWN Stranded will be used for all incoming and out-going ground wire. Bonding of each pole on the reverse side will also be #6 or #8. An additional ground wire will be run from the reverse side of this terminal, out the bottom of the service disconnect, to a grounded threaded Rigid incoming fitting, located at the outside top of the service disconnect box, where a weather proof threaded top plate attachment will connect to the steel tubing going to the dairy barn attic. This will attach to a Threaded LN-B 90 elbow, attached to a Steel EMT tubing (EMT tubing located inside the attic, no outside exposure of EMT will occur) to the Sub-Panel located inside. {Gray PVC from underground will be incoming to the bottom of the Outside Service Disconnect, feeding the 2-#2 hot, 1-#2 Neutral and 1-#6 Ground, all THHN/THWN}
All ground poles will be bonded together on the power distribution terminal that will be used as a seperate ground terminal.
If Sheetmetal screws are not sufficient for attaching the seperate ground terminal, then hex nuts (Nyloc type)with inside star washers and bolts will be used to attach to the box. Surely this will equate or surpass the screws. The ground wire going to the ground attachment on the outside fitting for the rigid, should ground the entire box, rigid pipe, fitting, etc. It does appear that the neutral is insulated, not grounded with a bonding screw.
This should ensure that the neutral and ground will be insulated from each other. There was no "green Screw" on this service disconnect box. An earlier inquiry suggested to feed the neutral completely thru the service disconnect. Due to pre-cut lengths of wire, this is not possible. I would rather trust the terminals, than to use an in-line patch/splice with shrink wrap tubing. This may not be standard, but if applied properly, it it technically non-code? What are accepted connection attachments (Hex nuts/bolts) for connecting the terminal (used for ground) to the service disconnect box?
The picture in the previous post, appears exactly as the ground terminal located inside my GE Sub-panel box which will be inside the Dairy barn. That particular breaker box is an outdoor rated type. The service disconnect located outside is simply a small box with 100 amp breaker only. The picture I have posted is rated at 175 amps max @ 75 degrees, 2/0 to #14 wire, with adequate inputs for the wire sizes I will be using. Although not what you are used to seeing being used, is it a code violation?

Back to my original question, should the neutral and ground sides of the SUB-PANEL breaker, located inside the dairy barn be seperated? Will this have an effect on the GFCI breakers installed in the dairy barn, if the bond between the neutral and ground is broken in the sub-panel? IMG]http://www.grainger.com/Grainger/productdetail.jsp?xi=xi&ItemId=1611778322[/IMG]

 

Yes.
No.
He didn't. It's a hyperlink.