Service disco requirement

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wrobotronic

Senior Member
Location
Colorado
Hi,
I have a commercial service to look at today. From the utility transformer the feed is two Al 500s for 480/277 vac, 600A service. There is no main disco. I am being told, however, that there are not more than six breakers (two 100a and three 200a) in the distribution cab and a main is not required. While this seems to be following the code, something just doesn't seem right. The cabinet appears to be engineered to only accept the five breakers that are in there now. Question is do I need to require the EC to provide documentation that the cab will only accept five breakers and thus comply with the six handle rule? Or am I missing something and a main disco is in fact required. I can't seem to find anything in 230 that requires a main, (I may be missing something however) even though it's a pretty sizable service. Thank you.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
If the panel is identified as "Suitable for Use as Service Equipment" it is acceptable as is with no additional documentation.,
Without a main, documentation may be required to asure the calculated load does not exceed the ampacity of the conductors and panel.
 

MasterTheNEC

CEO and President of Electrical Code Academy, Inc.
Location
McKinney, Texas
Occupation
CEO
Greetings wrobotronic -

1) The reference to "not more than six" is located in Section 230.71(A)
2) As Augie47 stated - See 230.66 for markings
3) Also as Augie47 eluded too as well, check out 230.90(A) Exception No. 3 for additional guidance

We will assume you did perform a load calculation and and have a calculated load that does not exceed the ampacity of the service conductors. Which I am sure you have done but always need to mention.
 

wrobotronic

Senior Member
Location
Colorado
Yes, performed the all the proper calculations for wire and ampacity. And my first thought was correct, as you all pointed out. With the size of the service I just wanted to make sure I was in the right line of thinking. Thank you all for the responses.
 
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