joeyww12000
Senior Member
- Location
- Chatsworth GA
Ok, Ive posted about this the past three or four times. The service I have been posting about passed inspection today and I freaked out. I just dont see how it passed and now Im thinking I dont know anything about grounding and bonding....so I am going to lay this service out one more time exactly how it was today when it passed inspection.
From the service transformer to service disconnect outside building - 2 sets of 4/350cu. PVC underground
The service grounded/neutral conductor is bonded to the disconnect can with a bonding strap and has a 2/0cu grounding conductor from that same point out to a groundrod which is then connected to building footer.
The service disconnect then feeds a automatic transfer switch for a backup gen. The grounded conductor is not switched. It is terminated to the proper lug. A equiment bonding jumper comes from the disconnect grounded/neutral conductor bonding point into the transfer switch and terminates to the can.
From the transfer switch you go underground with pvc up into the MDP. The grounded/neutral conductor terminates to the correct lug inside MDP. The system bonding jumper terminates to the MDP can. Everything is correct up to this point. The equimpent bonding jumper and the grounded/neutral conductor are seperated after the disconnect all the way to the MDP.
Now for the part I think is wrong. From the EGC point on the MDP can you have an EGC that goes to a 480/277v panel fed from a breaker in the MDP. This EGC goes directly to the panels neutral bar along with the grounded/neutral conductor. Then a bonding strap comes off the neutral bar bonding the panel can. Shouldnt the EGC go to the panel can and the neutral only to the neutral bar without a bonding strap installed???
Thats not it. Get this. This panel feeds another panel beside it. The EGC on the feeder panels neutral bar is taken to the subpanels neutral bar along with the neutral. So you have two panels with an EGC and a Neutral sharing a common point on both panels with bonding straps on each too.
Thats not it. Get this. The 480/277v panel also feeds a 208/120v transformer. Along with the phase conductors a EGC was pulled into the transformer. The egc comes off a ground lug attached to the feeder panel above. Inside the transformer from xo you have a bonding jumper to a lug on the can, this is where the egc from the feeder panel and the EGC going out to the first 208/120v panel is terminated. Also from xo you have the new system neutral going out to the neutral termination point at the 208/120v panel. At the panel you have the egc terminated to a ground lug kit, and a grounded neutral conductor to its correct terminating point. The bonding screw is put in the neutral bar. Since the bond is made at the panel shouldnt the grounding electrode conductor be brought from the bonding point out to the closest grounding electrode?
Also what will happen since the new system neutral from the xfmr is actually bonded to the neutral from the 480/277v panel? Im sorry this is a long post but I would like to know why this installation passed inspection. Any help would be apprectiated
From the service transformer to service disconnect outside building - 2 sets of 4/350cu. PVC underground
The service grounded/neutral conductor is bonded to the disconnect can with a bonding strap and has a 2/0cu grounding conductor from that same point out to a groundrod which is then connected to building footer.
The service disconnect then feeds a automatic transfer switch for a backup gen. The grounded conductor is not switched. It is terminated to the proper lug. A equiment bonding jumper comes from the disconnect grounded/neutral conductor bonding point into the transfer switch and terminates to the can.
From the transfer switch you go underground with pvc up into the MDP. The grounded/neutral conductor terminates to the correct lug inside MDP. The system bonding jumper terminates to the MDP can. Everything is correct up to this point. The equimpent bonding jumper and the grounded/neutral conductor are seperated after the disconnect all the way to the MDP.
Now for the part I think is wrong. From the EGC point on the MDP can you have an EGC that goes to a 480/277v panel fed from a breaker in the MDP. This EGC goes directly to the panels neutral bar along with the grounded/neutral conductor. Then a bonding strap comes off the neutral bar bonding the panel can. Shouldnt the EGC go to the panel can and the neutral only to the neutral bar without a bonding strap installed???
Thats not it. Get this. This panel feeds another panel beside it. The EGC on the feeder panels neutral bar is taken to the subpanels neutral bar along with the neutral. So you have two panels with an EGC and a Neutral sharing a common point on both panels with bonding straps on each too.
Thats not it. Get this. The 480/277v panel also feeds a 208/120v transformer. Along with the phase conductors a EGC was pulled into the transformer. The egc comes off a ground lug attached to the feeder panel above. Inside the transformer from xo you have a bonding jumper to a lug on the can, this is where the egc from the feeder panel and the EGC going out to the first 208/120v panel is terminated. Also from xo you have the new system neutral going out to the neutral termination point at the 208/120v panel. At the panel you have the egc terminated to a ground lug kit, and a grounded neutral conductor to its correct terminating point. The bonding screw is put in the neutral bar. Since the bond is made at the panel shouldnt the grounding electrode conductor be brought from the bonding point out to the closest grounding electrode?
Also what will happen since the new system neutral from the xfmr is actually bonded to the neutral from the 480/277v panel? Im sorry this is a long post but I would like to know why this installation passed inspection. Any help would be apprectiated
