Service Entrance Rated Panelboard with no main breaker

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philly

Senior Member
I am looking at a riser diagram that shows a 480V 1200A Panelboard being directly fed from a 500kVA utility transformer. The 1200A panelbaord is a MLO panel with no main breaker. I am being told that this particular is a service entrance rated panel and thus only needs a main switch upstream of this panel.

I have never seen a panel, switchboard, etc... used for the service entrance that does not have a main breaker? Has anyone seen this before, or can you provide me with additional info or applicable code sections?

What about ground fault detection/protection for this application? Is it required?
 
iwire

iwire

Moderator
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Location
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philly said:
I am looking at a riser diagram that shows a 480V 1200A Panelboard being directly fed from a 500kVA utility transformer. The 1200A panelbaord is a MLO panel with no main breaker. I am being told that this particular is a service entrance rated panel and thus only needs a main switch upstream of this panel.

I have never seen a panel, switchboard, etc... used for the service entrance that does not have a main breaker? Has anyone seen this before, or can you provide me with additional info or applicable code sections?

What about ground fault detection/protection for this application? Is it required?
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This is a common way to save money, as long as the panel has less than six breakers installed it is fine. And as long as none of them are more than 1,000 amps no GFP required.

There is also no NEC requirement for a main switch ahead of it. As a a matter of fact I think putting an unfused switch ahead of it would be a violation.
 
jumper

jumper

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iwire said:
This is a common way to save money, as long as the panel has less than six breakers installed it is fine. And as long as none of them are more than 1,000 amps no GFP required.

There is also no NEC requirement for a main switch ahead of it. As a a matter of fact I think putting an unfused switch ahead of it would be a violation.
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:angel:
 
kwired

kwired

Electron manager
Location
NE Nebraska
And only for solidly grounded wye systems operating at over 150 volts to ground but no more than 600 volts phase to phase. (230.95)
 
Smart $

Smart $

Esteemed Member
Location
Ohio
iwire said:
Yes, English is not my first language.:D
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Uhh... that would be technical English. If it were just English, I'd not understand but a fraction of a percentage of your posts... but wait a minute, maybe that's why we disagree a lot. :p
 
iwire

iwire

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Smart $ said:
Uhh... that would be technical English. If it were just English, I'd not understand but a fraction of a percentage of your posts... but wait a minute, maybe that's why we disagree a lot. :p
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I think it has to more to do with you being wrong a lot.:p
 
Dennis Alwon

Dennis Alwon

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Sometimes the code states more than a XXXX amps and sometimes it states xxxx amps or more--- I know I screw them up when I go from memory on some code articles.
 
jumper

jumper

Senior Member
Location
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Dennis Alwon said:
Sometimes the code states more than a XXXX amps and sometimes it states xxxx amps or more--- I know I screw them up when I go from memory on some code articles.
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Ditto, also the code always seems to write stuff in a way that easily misinterpreted if you go too quickly at times.

As for Bob, I think he just miswrote what he meant in this thread in his answer.
 
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ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Consulting Electrical Engineer - Photovoltaic Systems
Dennis Alwon said:
Sometimes the code states more than a XXXX amps and sometimes it states xxxx amps or more--- I know I screw them up when I go from memory on some code articles.
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Actually, you'd have to use calculus to describe the difference. Approaching 1000A from the high side, any value is still more than 1000A until you actually get there. How many decimal places would you like? :D
 
Smart $

Smart $

Esteemed Member
Location
Ohio
ggunn said:
Actually, you'd have to use calculus to describe the difference. Approaching 1000A from the high side, any value is still more than 1000A until you actually get there. How many decimal places would you like? :D
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Depends on how significantly figured it is... :p
 
jumper

jumper

Senior Member
Location
3 Hr 2 Min from Winged Horses
ggunn said:
Actually, you'd have to use calculus to describe the difference. Approaching 1000A from the high side, any value is still more than 1000A until you actually get there. How many decimal places would you like? :D
Click to expand...

First I want to see the limits, extrema, any discontinuities, and a vertical line test on the function before I will discuss any derivitive.:p

If an integral is gonna be part of the discussion I want no part of it.:D
 
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