I've got this industrial yard where they want to install 3 400A 3-ph. panels that will have a few welders. The panels will be located in a row directly in front of the SES that will feed them, with the first panel 100' directly in front of the SES. The second panel will be 150' to the right of the first panel, and the third panel will be 250' to the right of the second panel. So there is kind of an 'L' shape between the SES and the three 400A panels. Do each of the 400A panels need a main breaker and a couple of ground rods? There are no structures in this industrial yard, and this is really a temporary set up (it'll be torn down and all panels removed when the job is done). I do not believe there are any obstructions of line of site between the SES and the panels.
When is a main breaker & grounding system required (industrial yard)?
- Thread starter donw
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
"Buildings or Structures" require a main disconnecting means in or on the building or structure. You can have up to six disconnecting mean though.
2020 code however has some changes that may not allow all six to be in same enclosure, especially if it is service equipment.
Some might say this is equipment and not a structure, you still need to attach it to something unless it is pedestal type equipment.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Many people would consider them "structures" then (although I think that's tenuous). Not time to cehck at the moment, but is there anything in 590 that would assist?
Thanks for the idea. I skimmed 590 briefly and didn't see anything that would help answer the question.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Most of what would apply in 590 is the allowance of flexible cords or possibly even laying raceway on the ground if physically protected in some manner. Overcurrent protection, conductor ampacity, services, feeders, branch circuits mostly still need to follow general rules of chapters 1-4
powerpete69
Senior Member
- Location
- Northeast, Ohio
- Occupation
- Professional Electrical Engineer
Hard to understand what OP is asking, I don't believe you need a main breaker in each panel whether they are permanent or temporary.
Also, I don't believe you need a ground rod at each panel whether it is temp or not.... the ground in the feeder conduit should suffice.
How are these panels being fed? Underground conduit? Overhead conduit? Armored cable and ladder? Extension cords? What?
Also, I don't believe you need a ground rod at each panel whether it is temp or not.... the ground in the feeder conduit should suffice.
How are these panels being fed? Underground conduit? Overhead conduit? Armored cable and ladder? Extension cords? What?
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Please give us the code rule that that exempts this work from having a main breaker or ground rods.
powerpete69
Senior Member
- Location
- Northeast, Ohio
- Occupation
- Professional Electrical Engineer
Perhaps I don't understand the question in regards to "industrial yards" or what an "SES" is.
I am picturing the main service entrance being grounded with ground rods and a feeder breaker feeding each of these outside panels. If that is not the case, please advise.
Is there a code requirement that states you need a main breaker in outside temporary "industrial yard" panel installations instead of a MLO?
Is there a code requirement that states you need a ground rod in outside temporary"industrial yard" panel installations?
SES (services entrance section) will have a grounding system (rods) and a main breaker. I am referring to each of the three 400A panels that will be several hundred feet away from the SES. The panels will be fed underground with conduit.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
It will all depend whether or not it is considered separate building or structure that is being supplied.
If it is, 1 to 6 mains is required and a grounding electrode system is also required.
Another C10
Electrical Contractor 1987 - present
- Location
- Southern Cal
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- Electrician NEC 2020
My take on this question is you are installing 3- 400 Amp 3 phase panels , ( nice job by the way ) so somewhere there is a 1200+ Amp supply which will feed the 3 panels individually I presume ( each having a 400A main), thinking three 2 -2-1/2"" conduits each with 3- 4/0 and a 2/0 ground, unless specified different. If each panel has less than 6 breakers positions typically in ( calif. ) there is no need for a main at the panel - more than 6 ( main is required) solely intended for a fire life safety personnel, although its temporary and probably wont need an inspection. The grounding rods typically from my understanding are solely for the metered section were the utilities return shares the neutral ground reference. I'd say no on additional ground rods, just run the reference from the metered panel that way there is no secondary path return due to soil indifference. In (calif ) the rule use to be within 25' or within sight of the disconnecting means, in this case its not a piece of serviceable equipment its a distribution panel.
This is a great website to get valuable input.
Valuable input indeed! Thanks. I just wish the NEC would be more clear on such a simple issue.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I say no Grounding electrodes or main breakers needed. 225.32 and 250.32 are the code sections that might apply, however 2017 definitions of structure is "that which is built or constructed, other than equipment.” Note that even if those rules did apply, you might be able to use the 2-6 disconnect rule (not sure how may breakers you were planning on having). Of course there is some ambiguity as to what it takes to "build" something. A free standing switchboard would be 100% equipment, so I dont see why a panelboard on a post with some strut should be any different.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
It is clear, if it is a separate building or structure you need main disconnect(s) and a grounding electrode system.
The hardest part about this may be determining if it is a separate building/stucture.
Yeah, it would help if they made that more clear.
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