Mismatching MMCB Breaker and Enclosure Manufacturers

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jdewitt37000

Member
Location
Titusville, FL
Occupation
Electrical Contractor
The title probably explains it - but is it a violation to put say a 400AMP Square D Breaker into a 400AMP rated GE enclosure?
My understanding AIC ratings is that to be rated a breaker has to be installed in an enclosure listed for that breaker. So if you put a Square Breaker in a GE enclosure you will not have a listed assembly with a known withstand rating.

All other things being equal it seems to me that would be enough of a violation for an inspector to fail an installation.

That said I know that both Square D and Eaton custom make breaker & bus assemblies for old big switch gear and MCC bucket for obsolete equipment. I also know that Eaton makes kits to replace the interiors of FPE panels and I am pretty sure all of that is listed somehow or another.
 

jap

Senior Member
I don't think 404.3 would apply. If you read the scope, 404.1, it says:

"the provisions of this article shall apply to all switches, switching devices, and circuit breakers where used as switches."

An ECB used as a service disconnect would be a switch, switching device, and a circuit breaker used as a switch.

JAP>
 

cottora

Member
Location
Atlanta, GA
404.3 list exceptions - 110.27(A)(2) By suitable permanent, substantial partitions or screens arranged so that only qualified persons have access to the space within reach of the live parts. Any openings in such partitions or screens shall be sized and located so that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them.

Wouldn't this create an exception for externally operable? If the Enclosure is covered/flat front, then it is a suitable and substantial partition that would prohibit accidental contact.
 

jap

Senior Member
I'm not trying to argue a point.

I had all the same reasons you all are expressing.

Just saying that we've been turned down in the past for suggesting using an MLO paneleboard with a single breaker in it in place of an actual service disconnect where you pull the handle down.

Most larger service disconnects of the Enclosed Circuit Breaker type are externally operable even if the cover was locked shut.

It wasn't allowed because it wasn't externally operable like a true disconnect would be.

From then on, every time I hear "Mount a breaker in and enclosure" ,(Such as a Hoffman Enclosure or the like where you have to do something other than simply lift the lid to get to it ) it reminds me.

JAP>
 
I'm not trying to argue a point.

I had all the same reasons you all are expressing.

Just saying that we've been turned down in the past for suggesting using an MLO paneleboard with a single breaker in it in place of an actual service disconnect where you pull the handle down.

Most larger service disconnects of the Enclosed Circuit Breaker type are externally operable even if the cover was locked shut.

It wasn't allowed because it wasn't externally operable like a true disconnect would be.

From then on, every time I hear "Mount a breaker in and enclosure" ,(Such as a Hoffman Enclosure or the like where you have to do something other than simply lift the lid to get to it ) it reminds me.

JAP>
I think that is absurd. MLO panelboards have been used by the electrical industry as service disconnects forever, I have never ever heard of an issue with it just because you have to open a door?
 

jap

Senior Member
I think that is absurd. MLO panelboards have been used by the electrical industry as service disconnects forever, I have never ever heard of an issue with it just because you have to open a door?

I didn't until that day either..... :)

JAP>
 

cottora

Member
Location
Atlanta, GA
All of this begs the question - do handles have to be accessible from the "outside". In other words, is it allowable to put the handle where you must open the enclosure to flip the handle? Our problem is solved if we can put the MCCB inside of an enclosure (without outside handle operations).
 

jap

Senior Member
All of this begs the question - do handles have to be accessible from the "outside". In other words, is it allowable to put the handle where you must open the enclosure to flip the handle? Our problem is solved if we can put the MCCB inside of an enclosure (without outside handle operations).

Sounds like you're wanting to put an alternate Brand Y breaker in an existing Brand X enclosed circuit breaker enclosure.

If the existing enclosure does not specifically indicated the brand and style of breaker that would allow it, I don't think you'll find a definite answer for that question here, or, from any breaker manufacturer for that matter.

JAP>
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
All of this begs the question - do handles have to be accessible from the "outside". In other words, is it allowable to put the handle where you must open the enclosure to flip the handle? Our problem is solved if we can put the MCCB inside of an enclosure (without outside handle operations).
In general, the NEC does not require handles to be 'outside' of an enclosure.

Many examples of 'flat front' service and disconnect switches have already been provided.
 

jap

Senior Member
In general, the NEC does not require handles to be 'outside' of an enclosure.

Many examples of 'flat front' service and disconnect switches have already been provided.

Are you saying an outside service disconnect could be a breaker mounted inside a 3r screw cover J-box or to a back plate of a Nema 12 Hoffman enclosure with a hinge cover?

JAP>
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
Are you saying an outside service disconnect could be a breaker mounted inside a 3r screw cover J-box or to a back plate of a Nema 12 Hoffman enclosure with a hinge cover?

JAP>
Yes.
However, you would likely need to provide an interior dead front that shields/covers the line side terminations.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
I would think a screw cover that requires a screwdriver (as opposed to thumb screws) would render the OCPD not readily accessible, a violation of 240.24(A).

Cheers, Wayne
 

cottora

Member
Location
Atlanta, GA
Yes.
However, you would likely need to provide an interior dead front that shields/covers the line side terminations.
This could work for us. We would actually have the enclosure inside, and the conductors would enter the building directly into the enclosure (or within conduit if there is a small run to the enclosure).

I don't think that the setup is really considered a service disconnect since it is a customer-owned transformer and the conductors to the enclosures originate from the secondary of said transformer.

I have always thought that "readily accessible" meant that the handle could be seen and accessed without having to "do" anything (like open another box).
 

cottora

Member
Location
Atlanta, GA
Yes.
However, you would likely need to provide an interior dead front that shields/covers the line side terminations.
After thinking about this, doesn't the 110.27(A)(2) exception render the whole argument mute? As an example, if I put a GE Breaker into an Eaton enclosure, I will meet the below exception allowed under 404.3(A).

404.3 list exceptions - 110.27(A)(2) By suitable permanent, substantial partitions or screens arranged so that only qualified persons have access to the space within reach of the live parts. Any openings in such partitions or screens shall be sized and located so that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
Service entrance equipment is usually treated differently then standard equipment, for example, UL has special requirements concerning barriers and bonding jumpers.
Pay attention to the NEC definitions for service locations and accessibility requirements or allowances. The secondary of a customer owned transformer is not a service entrance location although it has several similar requirements.

Why do you think 404.3 would apply to your situation?
 
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