Grounding of feeders in cable tray

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white stallion

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Location
El Paso, Texas
Have an installation with three feeders, each feeder is made up of three 3-500 KCMIL 2400V parallel feeders for approximate rating of 1320 Amps. The service originates at utility from three individual transformers and terminates at the medium voltage switchgear. All feeder cables are to be run in cable tray, no conduits. The question is: does each parallel cable run require its separate ground conductor rated for the full capacity of the three parallel feeders? Since there is no conduits involved, can only one ground conductor be used for all 9 - 500 KCMIL feeder?
 
A single equipment ground can be used for multiple feeders in the same raceway.

There are some confusing aspects to your post.
If you have three sets of conductors in parallel, connected at both ends, you have one feeder. If you have three separate feeders, serving separate loads, it's unnecessary to call them 'parallel', I think that's just confusing. Also why are you mentioning the service transformer and switchgear? Are the conductors you're asking about actually the service conductors? Hopefully what I said above still applies.

See 392.60 for particulars regarding cable trays and bonding.
 
There are three separate loads being fed by way of the cable tray. Each load is fed with a similar type of feeder. Each feeder is composed of 3 #500 KCMIL 2400V runs. There are no conduits involved. The service conductors enter the cable tray from the source and exit cable tray onto load. My question: Is one ground wire sufficient for the 3 parallel runs on the feeder for each load?
 
Re-read @jaggedben reply he answered well with relevant questions

"Service Conductors" are not "Feeders":
The two terms are mutually exclusive. You cannot apply Feeder rules (like EGC sizing) to Service Conductors:
* NEC Definition (Article 100) - Service Conductors: "The conductors from the service point to the service disconnecting means."
* NEC Definition (Article 100) - Feeder: "All circuit conductors between the service equipment... and the final branch-circuit overcurrent device."

If these conductors are upstream of the main disconnect, they are Service Conductors. Therefore, they do not utilize an "Equipment Grounding Conductor" (EGC). They utilize a Supply-Side Bonding Jumper (SSBJ).

"Three Loads" are not "Parallel":
If the installation feeds three separate loads, these are three separate circuits. They are not "parallel conductors.":
* 310.10(G) (formerly 310.10(H)) - Conductors in Parallel: This section explicitly requires parallel conductors to be "electrically joined at both ends."

If these runs go to three different loads, they are not joined at the load end. Therefore, they are Multiple Circuits, not Parallel Conductors. And if I'm reading you correctly "medium voltage switchgear" the three TX land there is where your OCPD will most likely be and the "Service Conductors" end there and they become feeders to the final OCPD at these three loads. So you need a EGC for each of those three in this case'

Hope this helps'
 
Thanks for your response. Let me simplify my question. Disregard the issue of the three separate loads. If we feed a load composed of 3 parallel runs of 3 #500 KCMIL 2400V cables equating to approximately 1320 Amps only one ground conductor is required to act as a supply-side bonding jumper, correct? My concern possibly requiring 3 separate grounds for each parallel set similar to feeders routed in three separate conduits.
 
It matters a lot what you mean by 'ground' and if they are actually feeders or service conductors.

For feeders, meaning on the load side of the service disconnecting means, you can have one equipment grounding conductor if they are all in one cable tray. You can even use the cable tray as ground in certain circumstances. See my earlier reply for reference.
 
Are you installing a Service or not? This proves that definitions matter. Service conductor size is based on wire, while Feeder rules are based on the breaker.

The answer is yes, in either case Service or Feeder you can use one wire.

But pay attention to:

*IF THEY ARE "Service Conductors" in a Cable Tray, you can use a single Supply-Side Bonding Jumper (SSBJ) for the parallel group:
250.102(C)(2), in your case prob a 2/0 CU or 4/0 AL:

https://imgur.com/a/kzcdI1n

*IF THEY ARE "Feeders" in a Cable Tray, you can use a single EGC (Equipment Grounding Conductor) for the parallel group. 250.122(F)(1), in your case prob a 4/0 CU or 350 AL.

https://imgur.com/a/O2UpAeH

The real heads up here is the sizing. Boss man hates it when you oversize the ground wire by two full trade sizes :)
 
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