Breaker trip setting to less than 1200 Amps OK ??? - 110.26(C)(2)

[sam@ssw]

Ref: Article 110.26(C)(2) - Egress from Working Space:
We have a 2,000 Amp main circuit breaker in a 2,000 Amp rated MCC that is 9.6 ft. wide. The working space we have in front of this MCC is about 4 ft. to other electrical equipment on the opposite wall of the electrical room.

If we lower the Trip Setting on this 2,000 Amp main circuit breaker to LESS than 1,200 Amp setting, will the requirement of 110.26(C)(2) no longer apply? Please advise. (Would appreciate a quick response as we are trying to make a decision...)
Thanks.

 

[iwire]

a 2,000 Amp rated MCC

110.26(C)(2) Large Equipment. For equipment rated 1200 amperes
or more and over 1.8 m (6 ft) wide that contains overcurrent
devices, switching devices, or control devices, there
shall be one entrance to and egress from the required working
space not less than 610 mm (24 in.) wide and 2.0 m
(61?2 ft) high at each end of the working space.

A single entrance to and egress from the required working
space shall be permitted where either of the conditions
in 110.26(C)(2)(a) or (C)(2)(b) is met.

The MCC is rated more than 1,200 amps.

 

[charlie b]

I agree with Bob (it does happen on occassion :happyyes: ). It is not the trip setting that matters, for that could be easily turned back up at a later date.

 

[sam@ssw]

Thanks for the replies so far.

So, it sounds like what matters is the RATING of the equipment and not the adjustment nor the main breaker trip setting.
Having said this, what if we have a fixed 1,000 Amp rated main breaker in a 1,200 Amp rated MCC? Then, will the requirement of 110.26(C)(2) still apply?

 

[zog]

What if you change the rating plug (or CT's, or series trip device depending on what type of breaker it is) to <1200A? That way it becomes the AT rating and cannot be simply "turned back up".

 

[iwire]

The equipment is rated more than 1200 amps, there is no way around that.

If they meant the size of the over-current device that is what the section would say.

 

[don_resqcapt19]

Bob has it correct. The rating of the OCPD has nothing to do with this rule. The only rating that matters is the rating of the equipment itself.

 

[kwired]

I agree is says equipment rated 1200 amps or more. Don't know if I agree that is what it should say.

I think one needs to know what the intention was when they decided to put in this rule in the first place, and maybe based on that the section could possibly use some modification." Why do they want more egress ability, and why at that particular amp level? Quite frankly I think arc flash potential should probably be a bigger player in here then just the general rule of 1200 amps or more, though anything designed to carry 1200 amps typically will have higher arc flash hazard levels, but doesn't mean you can't have a pretty high level at only 400 amp gear either.

But for now and what it does say, I guess a 20 amp breaker in 1200 amp gear still needs to comply.

 

[templdl]

Wouldn't one consider a breaker that is classified as having a NIT or non interchangeable trip unit and not adjustable? As such it would require a qualified person to change the trip unit rating.

 

[GoldDigger]

Wouldn't one consider a breaker that is classified as having a NIT or non interchangeable trip unit and not adjustable? As such it would require a qualified person to change the trip unit rating.

Sure, but that still does not change the rating of the equipment containing the breaker. It just makes it more of a technicality than a direct safety argument. But the Code says what the Code says and the AHJ has to interpret it.

 

[templdl]

Sure, but that still does not change the rating of the equipment containing the breaker. It just makes it more of a technicality than a direct safety argument. But the Code says what the Code says and the AHJ has to interpret it.

A 1200a frame with an 800a NIT unit or a nonadjustable trip unit? It is obvious that you can't change the rating of the other quipment. Is there an issue with feeding a 1200a rated piece of equipment with a 1200af breaker that has a nonadjustable 800a trip?
Oherwise it would require that the area be accessed only by qualified personal who would not arbitrarily change the trip setting.

 

[hardworkingstiff]

What if the manufacturer installed a lower OCP and then rated the equipment lower (and installed new labels to say just that)?

 

[kwired]

What if the manufacturer installed a lower OCP and then rated the equipment lower (and installed new labels to say just that)?

Which does kind of happen with smaller equipment, but none of it comes close to the 1200 amp rating that triggers the rules of this discussion. Example may be a 150 amp compared to a 200 amp panelboard. Both may be exact same components except for the setting of the main breaker.

Something tells me there will be a significant enough difference though in the amount of material used to construct an 1000 vs a 1200 amp bus.

 

[sam@ssw]

Thank you all who have taken the time to respond to this inquiry.