600 amp service install

T

Therealcrt

Senior Member
Location
Kansas City
Occupation
Electrician
Gonna be doing a new 600 amp service install at a warehouse,service feeders from transformer to A CT cabinet from my CT cabinet to the tenants. Space. I’m gonna be pulling aluminum so I figured 500 is good for 310 at 75°C so I’ll be running parallel 500 each set in a 3 inch conduit three phase 480 V

I just have a few questions. When are the use of bonding bushings required do I need to use them in my CT cabinet if the voltage is 277 or greater to ground whether or not I use a whole punch or a concentric/eccentric knockout since it’s at the service.

Also, I believe I’m gonna be using window current transformers I’ve done them before and I always remember that the white dot that’s painted on there faces the primary side, but I’ve seen various rules as far as I have to remove the mounting bracket on the back is that specific to the AHJ or is that common and also is there a manual that comes with those CT’s that state that I must do that?
 
If the metal service raceways are ahead of the service disconnect then a bonding bushing or other means beyond the standard locknuts is required on one end to bond the raceways. If there are no concentric or eccentric KO's then a bonding locknut is sufficient. If there are concentric or eccentric KOs then the bonding bushing would be required. CTs should fall under the rules of the POCO.
 
So the raceways from the CT enclosure to the service disconnect need to be bonded at either side? Probably inside the CT cabinet. Why not both sides
 
Eddie702 said:
The neutral will bond the service enclosure and the CT cabinet. The bonding bushing bonds the nipple so no need to do that on both ends.
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What Eddie said. The bonding of the metal raceway is not there to provide continuity across the two pieces of equipment it's merely ensuring that the metal raceway is properly bonded.
 
Just make sure you understand your utility company rules...ours requires metal conduits that contain service conductors to be bonded at both ends. Yes, I know that that is covered by the NEC and the NEC does not require both ends to be bond, but the utility does and if you want your power connected, you will bond both ends.
 
What about from CT cabinet to meter can? And also my GEC should I run from ground rod to the meter can (which my poco requires always) and also run one to my main disconnect?
 
infinity said:
If the metal service raceways are ahead of the service disconnect then a bonding bushing or other means beyond the standard locknuts is required on one end to bond the raceways. If there are no concentric or eccentric KO's then a bonding locknut is sufficient. If there are concentric or eccentric KOs then the bonding bushing would be required. CTs should fall under the rules of the POCO.
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But what if there are no concentric or eccentric knockouts are encountered at any of the service enclosures? Regardless of the voltage. A rigid nipple is a method of bonding so I would not need any bonding bushings of any type if I do not encounter any concentric or eccentric knockouts at any of the service enclosures correct?
 
Therealcrt said:
But what if there are no concentric or eccentric knockouts are encountered at any of the service enclosures? Regardless of the voltage. A rigid nipple is a method of bonding so I would not need any bonding bushings of any type if I do not encounter any concentric or eccentric knockouts at any of the service enclosures correct?
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The enclosure is not relevant. It's dependent on what type of conductors are within the raceway. Raceways containing feeder conductors and service conductors can have different requirements. For a feeder raceway with fully punched KO's standard lock nut(s) are all that are required to bond the raceway. If the raceway contains service conductors then something better than a standard locknut(s) is required on one end. For full punched KO's it could be a bonding locknut. For concentric or eccentric KO's a bonding bushing would be required.
 
Therealcrt said:
What about from CT cabinet to meter can? And also my GEC should I run from ground rod to the meter can (which my poco requires always) and also run one to my main disconnect?
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Ask the utility what you're supposed to connect the GEC to in a CT meter.
 
infinity said:
The enclosure is not relevant. It's dependent on what type of conductors are within the raceway. Raceways containing feeder conductors and service conductors can have different requirements. For a feeder raceway with fully punched KO's standard lock nut(s) are all that are required to bond the raceway. If the raceway contains service conductors then something better than a standard locknut(s) is required on one end. For full punched KO's it could be a bonding locknut. For concentric or eccentric KO's a bonding bushing would be required.
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Site the code reference for that of the raceways containing service conductors, regardless of enclosure then.. I’m seeing in the 2017 code book, 250.92 (B) (1,2,3,4) are all methods of Electrical continuity “Bonding”

As to which (2) states connectors utilizing threaded couplings or threaded hubs on enclosures made up wrench tight

And as to which (3) states threadless, couplings, and connectors, if made up tight for metal raceways and metal clad cables.

So my question is why are bonding bushings or locknuts required for a metal raceway containing service conductors that do not enter an enclosure using reducing washers, or oversized concentric or eccentric knockouts like you are saying?
 
roger said:
Ask the utility what you're supposed to connect the GEC to in a CT meter.
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But that is not my first means of disconnect, my main disconnect will be piped from the other side of my CT Cabinet. So there I will bond the neutral and ground but that was my question is can I not run my GEC into my gutter to a ground bar and then a main bonding jumper through that gutter to my main disconnect and bond it to the neutral that way? And then also tap off that ground bar in the gutter and go up to the meter enclosure even though the meter will not contain any service conductors?
 
Therealcrt said:
Site the code reference for that of the raceways containing service conductors, regardless of enclosure then.. I’m seeing in the 2017 code book, 250.92 (B) (1,2,3,4) are all methods of Electrical continuity “Bonding”
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250.92(B) Method of Bonding at the Service.
Bonding jumpers meeting the requirements of this article shall be used around impaired connections, such as reducing washers or oversized, concentric, or eccentric knockouts. Standard locknuts or bushings shall not be the only means for the bonding required by this section but shall be permitted to be installed to make a mechanical connection of the raceway(s).
 
Therealcrt said:
I talked to my plan and developer for Evergy here in KCMO and they require ALL meter enclosures to have a grounding electrode conductor.
Not the CT Cabinet.
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Once again what do they think it will connect to? The GEC is for connecting the neutral to earth, there is no service neutral in a CT meter
 
Therealcrt said:
I talked to my plan and developer for Evergy here in KCMO and they require ALL meter enclosures to have a grounding electrode conductor.
Not the CT Cabinet.
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I don't believe that what you're saying is in reference to a CT meter. The CT meter is in a separate enclosure and does not contain the full size service neutral. Most meter wire is #9 or #10 AWG so I don't think that they want you running a #3/0 GEC to connect to that. This a 10 point meter pan for a CT metered service.10 point meter pan.jpg
 
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infinity said:
250.92(B) Method of Bonding at the Service.
Bonding jumpers meeting the requirements of this article shall be used around impaired connections, such as reducing washers or oversized, concentric, or eccentric knockouts. Standard locknuts or bushings shall not be the only means for the bonding required by this section but shall be permitted to be installed to make a mechanical connection of the raceway(s).
Click to expand...

infinity said:
250.92(B) Method of Bonding at the Service.
Bonding jumpers meeting the requirements of this article shall be used around impaired connections, such as reducing washers or oversized, concentric, or eccentric knockouts. Standard locknuts or bushings shall not be the only means for the bonding required by this section but shall be permitted to be installed to make a mechanical connection of the raceway(s).
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Ok, so then in this case my service conductors enter a gutter from underground conduits PVC from transformer. Then from that gutter there’s a nipple to the CT Cabinet, (that nipple would need a bonding locknut or bushing on one side of it). Then it nipples to the main disconnect from the CT Cabinet. (That nipple would need a bonding bushing or locknut on one side) and then a short piece of EMT into the ct meter enclosure, (does that need a bonding locknut or bushing one one side too?)

All those bonding jumpers from the bonding bushings to the enclosure are sized according the the supply side bonding jumper chart correct?
 
So they want the GEC routed through the 1.25" (#3) raceway to the neutral in the CT cabinet. As Infinity said in post #17 that can be a problem with large GEC's.
 
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