Adding Equipment Grounding bus to Existing Service Disconnect

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xguard

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Baton Rouge, LA
I have a couple of feeders I want to add an equipment grounding conductor to, the 400 A and 800 amp feeders shown below.


Service disconnect ---800A feeder---distribution panel ---400A feeder---"appliance" panel.


I'm replacing the 400 A "appliance " panel and know the 400 A feeder and 800 A feeder are using rigid metal conduit that was ran underground 40 years ago as the EGC. I'm seriously doubting the underground rmc is any good. The service disconnect though doesn't have a bus to land an EGC (or a grounding electrode conductor for that matter). Can I add a bus to it? If so is there a general retrofit product that's typically used for this?
 
xguard said:
I have a couple of feeders I want to add an equipment grounding conductor to, the 400 A and 800 amp feeders shown below.


Service disconnect ---800A feeder---distribution panel ---400A feeder---"appliance" panel.


I'm replacing the 400 A "appliance " panel and know the 400 A feeder and 800 A feeder are using rigid metal conduit that was ran underground 40 years ago as the EGC. I'm seriously doubting the underground rmc is any good. The service disconnect though doesn't have a bus to land an EGC (or a grounding electrode conductor for that matter). Can I add a bus to it? If so is there a general retrofit product that's typically used for this?
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It seems to me that how to land the EGC is the least of your problems. How do you plan to get an EGC in the existing raceway. Maybe I'm misunderstanding?
 
texie said:
It seems to me that how to land the EGC is the least of your problems. How do you plan to get an EGC in the existing raceway. Maybe I'm misunderstanding?
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Its not a long run, I'm planning on running new circuits over head inside the building. The 800 A feeder goes underground, under the footing then in the building. The 400 A feeder goes into the slab then out , I'm not sure if it gets down in the dirt or not.
 
If the EGCs are originating at the service disconnect, you can connect them to the grounded conductor bus.
 
Bolt your new ground bar to the enclosure - removing paint if necessary. That is exactly how it is done on most new panels, the bonding jumper bonds the enclosure, and you pick up the EGC because the terminal bar is bolted to the enclosure. They may not remove paint, but this is because their method of attachment is tested and listed as is. As is field attachment with specific hardware to a designated location. Your field installation is not tested and listed so paint removal or other methods of ensuring continuity are needed.
 
don_resqcapt19 said:
What is being used for the main bonding jumper now? Where is the grounding electrode conductor connected?
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I don't see a main bonding jumper now. It appears the grounded service conductor is currently not bonded to the enclosure. I also haven't seen where the grounded service conductor is connected to the grounding electrode conductor. The only grounding electrode I see has a conduit going into the ct cabinet. I plan to have the utility come out come out and open it this week.

.
 
kwired said:
Bolt your new ground bar to the enclosure - removing paint if necessary. That is exactly how it is done on most new panels, the bonding jumper bonds the enclosure, and you pick up the EGC because the terminal bar is bolted to the enclosure. They may not remove paint, but this is because their method of attachment is tested and listed as is. As is field attachment with specific hardware to a designated location. Your field installation is not tested and listed so paint removal or other methods of ensuring continuity are needed.
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Thanks! I can use any grounding bar to do this?
 
xguard said:
Thanks! I can use any grounding bar to do this?
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You can, BUT, you need to assure your grounded conductor/buss is bonded to the enclosure so you have a low impedance path. (250.28, 250.24)
 
xguard said:
Thanks! I can use any grounding bar to do this?
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Yes, if you have no main bonding jumper (make sure there is no screw that is serving that purpose that is not identified very well - older equipment can be good at not identifying very well) then you can make your own jumper - it needs sized to 250.66 and could land in this bar. You will have trouble connecting it to the neutral bus if there is no open spaces though. It is possible to tap it directly from the incoming neutral conductor I guess with proper splice/tap device.

Note that if neutral bus is not on insulators and is bolted directly to the enclosure that it is already serving the main bonding jumper purpose.
 
I'm not sure we have enough details here of the exact layout, voltage, size, etc. Is there 1 main or multiple? Is there any GFPE involved? If so, the OP will want to be careful where he lands any EGCs in the main disconnect.
This could also be a main panel SUSE ONLY (especially if it is as old as he indicates) and as such the neutral bond may not be readily visible.
 
kwired said:
Yes, if you have no main bonding jumper (make sure there is no screw that is serving that purpose that is not identified very well - older equipment can be good at not identifying very well) ...
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Given that he is connecting an 800 amp feeder to the service equipment, it is unlikely that the main bonding jumper would be a screw.
 
Depending on POCO practice, the bond between GES and grounded neutral may be in the CT cabinet or elsewhere upstream of what you see as the main disconnect.
If this is the case, the neutral and the EGC (maybe raceway) will enter the disconnect separately.
 
GoldDigger said:
Depending on POCO practice, the bond between GES and grounded neutral may be in the CT cabinet or elsewhere upstream of what you see as the main disconnect.
If this is the case, the neutral and the EGC (maybe raceway) will enter the disconnect separately.
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Even if that is the case, there would not normally be an EGC. The neutral is used as both the grounding and grounded conductor until you get to the load side of the service disconnect(s).
 
don_resqcapt19 said:
Given that he is connecting an 800 amp feeder to the service equipment, it is unlikely that the main bonding jumper would be a screw.
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True, also depends on your definition of "screw" I guess. Is there any official point where size determines what is a screw and what is a bolt or any other name, because I can think of many conflicting applications if there is a real difference.

Lets maybe just call it a threaded style fastener:)

GoldDigger said:
Depending on POCO practice, the bond between GES and grounded neutral may be in the CT cabinet or elsewhere upstream of what you see as the main disconnect.
If this is the case, the neutral and the EGC (maybe raceway) will enter the disconnect separately.
Click to expand...

don_resqcapt19 said:
Even if that is the case, there would not normally be an EGC. The neutral is used as both the grounding and grounded conductor until you get to the load side of the service disconnect(s).
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NEC has required the service disconnecting means enclosure(s), if conductive, to be bonded to the grounded conductor for a very long time AFAIK
 
I tried to attach a photo of where the Parallel Grounded Service Conductors land and the feeder Grounded Conductors begin. I have not tested it but the tan block looks non rather non-conductive to me. I will certianly verify that though. Thanks for the great input thus far, please tell me what you think of this photo.
 

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xguard said:
I tried to attach a photo of where the Parallel Grounded Service Conductors land and the feeder Grounded Conductors begin. I have not tested it but the tan block looks non rather non-conductive to me. I will certianly verify that though. Thanks for the great input thus far, please tell me what you think of this photo.
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Look like a kit for retrofit of doubled-up conductors. It's basically just a piece of buss-bar with some lugs. Probably designed for hots, thus the insulation block. While fine as it is, and while it could be tapped for another lug, the rust on the fasteners would preclude reuse of the existing hardware. I would probably make life easy for myself and replace it with a 5-hole version of an insulated cable connector:
polaris.jpg
Carried by your local electrical distributor. Search terms Polaris or Tork. They also have version with mounting lugs , a good idea for conductors ahead of the first OCPD. The fifth hole would be for a bonding jumper to your new ground bar.
 
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xguard said:
I tried to attach a photo of where the Parallel Grounded Service Conductors land and the feeder Grounded Conductors begin. I have not tested it but the tan block looks non rather non-conductive to me. I will certianly verify that though. Thanks for the great input thus far, please tell me what you think of this photo.
Click to expand...

starbolin said:
Look like a kit for retrofit of doubled-up conductors. It's basically just a piece of buss-bar with some lugs. Probably designed for hots, thus the insulation block. While fine as it is, and while it could be tapped for another lug, the rust on the fasteners would preclude reuse of the existing hardware. I would probably make life easy for myself and replace it with a 5-hole version of an insulated cable connector:
View attachment 10652
Carried by your local electrical distributor. Search terms Polaris or Tork. They also have version with mounting lugs , a good idea for conductors ahead of the first OCPD. The fifth hole would be for a bonding jumper to your new ground bar.
Click to expand...
I'm thinking it may be original neutral bus that come with the disconnect - possibly did not have lugs so user could select mechanical or compression lugs. The fact those lugs have two mounting holes yet don't match up to any holes in the bus kind of means to me they were field installed anyway.

The insulator it is mounted on - is pretty standard, otherwise if it were bolted directly to the can it would be suitable ONLY for use as service equipment.
 
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