Back fed breaker being used as main breaker in a main lug only panel

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Roy Rice

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Mesa, AZ.
Have a 42 space breaker panel main lug only, 208/120 3 phase 4 wire, rated for 250 Amps (Siemens). A 3 phase 90 Amp breaker was installed at the bottom left and is being used as the main breaker. Is this acceptable standards in a commercial application?
 

augie47

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Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Unusual but Code compliant on the surface. (the devil may be in the details)
 

Dennis Alwon

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I know certain panel will not accept a retainer clip but it must have one to be compliant.

I have never noticed a back fed rating of a breaker. I am not sure why that would be necessary.
 

david luchini

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Location
Connecticut
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Engineer
I have never noticed a back fed rating of a breaker. I am not sure why that would be necessary.

I think that by using a breaker that has "line" and "load" terminals as a back-fed breaker, you are violating the listing of the breaker by connecting "line" to the "load" terminals. Maybe its not so much that the breaker is listed as "back-fed" as that it is not listed for "line" and "load."

I remember reading about that issue on the MikeHolt website before. If I could find a link to the article, I'd post it.
 

iwire

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Staff member
Location
Massachusetts
Few if any 90 amp CBs will be marked line and load so forward, backward it does not matter.:)

However I do agree if it was marked line and load we would have to respect that labeling.
 

raider1

Senior Member
Staff member
Location
Logan, Utah
I think that by using a breaker that has "line" and "load" terminals as a back-fed breaker, you are violating the listing of the breaker by connecting "line" to the "load" terminals. Maybe its not so much that the breaker is listed as "back-fed" as that it is not listed for "line" and "load."

I remember reading about that issue on the MikeHolt website before. If I could find a link to the article, I'd post it.

That information comes from the listing of the breakers.

From what I have been told any breaker that is listed and labeled without a line and load marking have been evaluated and listed for back feeding.

Chris
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Have a 42 space breaker panel main lug only, 208/120 3 phase 4 wire, rated for 250 Amps (Siemens). A 3 phase 90 Amp breaker was installed at the bottom left and is being used as the main breaker. Is this acceptable standards in a commercial application?

I don't have a problem with it, with the details given. It seems a little odd, but it could well be code compliant.
 

norcal

Senior Member
If it is a bolt-on breaker, no hold down is required, only required on a plug-in type breaker.

408.36(F) 2008 ed.

(D) Back-Fed Devices. Plug-in-type overcurrent protection
devices or plug-in type main lug assemblies that are
backfed and used to terminate field-installed ungrounded
supply conductors shall be secured in place by an additional
fastener that requires other than a pull to release the
device from the mounting means on the panel.

Bolt-on main lug panel w/ back-fed main.

Picture158.jpg
 
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