400 Amp Service

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A/A Fuel GTX

Senior Member
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WI & AZ
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Electrician
I think I'm right on this but want to throw it out for opinions before I begin the job. I'm installing a 400A service for a farm. There will be a 400A ( 320A continuous ) meter socket fed from the POCO's lateral feeding a 400A MLO load center. From the load center, I will run three feeders to three separate buildings with the OCPD for each building in the load center. Of course, each building will have a disconnect of its own. The meter/load center combo will be in the middle of the property mounted on a board with 6 X 6 posts for support. In this scenario, I don't think I need a main breaker for the 400A load center since I'm below the 6 OCPD requirement..........Correct?
 

chevyx92

Senior Member
Location
VA BCH, VA
m73214 said:
I think I'm right on this but want to throw it out for opinions before I begin the job. I'm installing a 400A service for a farm. There will be a 400A ( 320A continuous ) meter socket fed from the POCO's lateral feeding a 400A MLO load center. From the load center, I will run three feeders to three separate buildings with the OCPD for each building in the load center. Of course, each building will have a disconnect of its own. The meter/load center combo will be in the middle of the property mounted on a board with 6 X 6 posts for support. In this scenario, I don't think I need a main breaker for the 400A load center since I'm below the 6 OCPD requirement..........Correct?
Sounds good to me.
 

iwire

Moderator
Staff member
Location
Massachusetts
It should have marking like this.

Suitableserviceequip.jpg
 

ceknight

Senior Member
m73214 said:
...In this scenario, I don't think I need a main breaker for the 400A load center since I'm below the 6 OCPD requirement..........Correct?

You don't need a main breaker, but I recommend getting a MLO panel with very limited space.

I know farmers. Give 'em 6 months and they'll have all their exterior lights and electric fencing and lord knows what coming out of that panel, probably rendering it unsuitable for service equipment any more. :)
 

wbalsam1

Senior Member
Location
Upper Jay, NY
iwire said:
As long as the panel is rated as service equipment as an MLO you are good to go.

Bob, here's a good place for me to learn something. Would the provisions of 547.9(A)(1) apply to the scenario in this thread? In other words, since there are several buildings supplied by these three feeders out of this MLO panelboard, would 547.9(A)(1) apply. :-? :) Or is this distribution point down wind of the service?
 

wbalsam1

Senior Member
Location
Upper Jay, NY
Dennis Alwon said:
Here's a question. What is a site isolating device?

Site-Isolating Device. A disconnecting means installed at the distribution point.....
Distribution Point. An electrical supply point from which service drops, service laterals, feeders......are supplied :)
 

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
iwire said:
I do not have my 2005 handy, what is 547.9? :confused:
Site isolating device-- shall be installed at the distribution point where 2 or more agricultural buildings, structures, assoc, farm dwellings or other buildings are supplied from the distrib. point.
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
wbalsam1 said:
Site-Isolating Device. A disconnecting means installed at the distribution point.....
Distribution Point. An electrical supply point from which service drops, service laterals, feeders......are supplied :)
Thank you---
 

wbalsam1

Senior Member
Location
Upper Jay, NY
iwire said:
I do not have my 2005 handy, what is 547.9? :confused:

547.9 Electrical supply to buildings or structures from a distribution point. Overhead electrical supply shall comply with 547.9(A) and (B) or with (C)....
547.9(A) Site-isolating device shall comply with 547.9(A) (1) thru (9)

547.9(A)(1) Where required. a site-isolating device shall be installed at the distribution point where two or more agricultural buildings...are supplied from the distribution point...:)
 

wbalsam1

Senior Member
Location
Upper Jay, NY
dbuckley said:
Is that required?

Although you are under the "six handle rule" and thus not required, I think it would be wise to have a main disconnect.

225.31 and 225.32 may apply to this thread. Of course 225.33 permits 6 throws of the hand. :) Providing that the farms loads require 6 or less circuits as per Part V of Article 220. :)
 

A/A Fuel GTX

Senior Member
Location
WI & AZ
Occupation
Electrician
dbuckley said:
Is that required?

Although you are under the "six handle rule" and thus not required, I think it would be wise to have a main disconnect.

Every detached building is required to have some sort of disconnect as far as I know.
 

brantmacga

Señor Member
Location
Georgia
Occupation
Former Child
ceknight said:
You don't need a main breaker, but I recommend getting a MLO panel with very limited space.

I know farmers. Give 'em 6 months and they'll have all their exterior lights and electric fencing and lord knows what coming out of that panel, probably rendering it unsuitable for service equipment any more. :)


you better believe it. i've been trying to do upgrades on our farm for the past couple of years now. i replaced an old fuse panel a couple of weeks ago that ran a two 500 gal gas pumps and two 20k gallon diesel tanks. i accidentally left off a connection for one of the gas pumps, and saw friday where my grandfather "fixed" it. he ran a two wire extension cord to the pump and stuck the leads on the pump into the end of it, and laid the connection on top of the tank. i almost freaked out, but then realized he's been doing things like this for 70 years and is still alive. so i made no mention of it and just fixed it.
 

A/A Fuel GTX

Senior Member
Location
WI & AZ
Occupation
Electrician
wbalsam1 said:
Bob, here's a good place for me to learn something. Would the provisions of 547.9(A)(1) apply to the scenario in this thread? In other words, since there are several buildings supplied by these three feeders out of this MLO panelboard, would 547.9(A)(1) apply. :-? :) Or is this distribution point down wind of the service?

This is an underground service so only 547.9 (C) and (D) would apply. Therefore, an isolating device would not be necessary. After reading 547.9 it seems that even an overhead service would not require an isolating device based on the options provided. So isolating devices appear to be a design choice, not a requirement.
 

mdshunk

Senior Member
Location
Right here.
For overhead, you often get a "free" site isolating device from the POCO when they do their work at the pole top. They'll almost always install a pole top disconnect for an ag CD pole, in my experience.
 
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