NEC Article 110.26 (C) (3) - Personnel Doors

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wbwald

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I am trying to determine if my interpretation of NEC Article 110.26(C)(3) is correct or where i am misguided.

I am designing an electrical room with a 4000 amp, 3 phase, 4 wire, 480Y/277V busway with (2) 400 amp busway disconnects, (2) 400 amp panels that feed 112.5KVA transformers that feed (2) 350 amp main breaker panelboards. This situation is typical for most of the tenant floors for a high rise office building. I have the code required clearances for all the equipment. My question is whether the door for the electrical room is required to swing out of the room and whether the door is required to have panic hardware? my initial interpretation is that the door has to swing out and have panic hardware?
 
I agree with you. I didn't at first, but reading the article revealed that the rating of the equipment (in this case, the busway) is what makes the difference, not the rating of the overcurrent devices or the ratings of the other panels in the room.
 
My copy of the 2008 is at home. So I can't answer this question. I do recall that the rules for "large equipment" changed several times between 2002 and 2017. I don't recall when the requirement related to personnel doors intended for egress from working space came into the code.
 
I don't see that room as having equipment "rated 800 A or more that contains overcurrent devices, switching devices, or control devices...".
 
don_resqcapt19 said:
I don't see that room as having equipment "rated 800 A or more that contains overcurrent devices, switching devices, or control devices...".
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Don, are you saying that the 4000 amp busway doesn't count? (I think that you had something to do with this rule). ;)
 
jumper said:
No 4000A switch, it is not mentioned in OPs description, just busway. Vertical riser I assume.
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The switch does not have to be 4000 amperes, the equipment only has to be rated 800 amperes or more and contain switches. The op stated the busway does have switches installed on it.
 
packersparky said:
The switch does not have to be 4000 amperes, the equipment only has to be rated 800 amperes or more and contain switches. The op stated the busway does have switches installed on it.
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But I do not see any one switch in the OP that is 800A or above, just the 4000A busway.

Am I missing something? Are you adding the switch ratings together for a total?
 
jumper said:
But I do not see any one switch in the OP that is 800A or above, just the 4000A busway.

Am I missing something? Are you adding the switch ratings together for a total?
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The ratings of the switches do not matter. It is the rating of the equipment that kicks in the requirement. You could have 1200 ampere switchgear filled with 20 amp breakers and 110.26(C)(3) would apply.
 
packersparky said:
The ratings of the switches do not matter. It is the rating of the equipment that kicks in the requirement. You could have 1200 ampere switchgear filled with 20 amp breakers and 110.26(C)(3) would apply.
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My confusion is that I am only basing my assumption that this rule applies to fact the 4000A busway is there. I do not see anything else in OPs description that is applicable.

Just trying to figure this out.
 
jumper said:
My confusion is that I am only basing my assumption that this rule applies to fact the 4000A busway is there. I do not see anything else in OPs description that is applicable.

Just trying to figure this out.
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The OP stated that the busway has 2-400 amp disconnects installed on the busway. IMO the requirement for outward swinging door and panic hardware would be applicable because the equipment (busway) is rated over 800 amps and it contains switches. This is assuming the door is within 25 feet of the working space.
 
packersparky said:
The OP stated that the busway has 2-400 amp disconnects installed on the busway. IMO the requirement for outward swinging door and panic hardware would be applicable because the equipment (busway) is rated over 800 amps and it contains switches. This is assuming the door is within 25 feet of the working space.
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Interesting, lemme think about that.. so we are looking at the fact the switch itself has to be rated for connection to the busway, and since the busway is rated 4000A, the two make the code section applicable in your opinion?
 
jumper said:
Interesting, lemme think about that.. so we are looking at the fact the switch itself has to be rated for connection to the busway, and since the busway is rated 4000A, the two make the code section applicable in your opinion?
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Yep. That's the way I see it anyway and the AHJ here looks at it the same way.
 
It seems to come down to whether the busway is considered to contain the switches (regardless of switch size). If it does then the busway itself would be equipment covered by the section.
If, on the other hand, you consider the switch to be attached to the busway rather than contained in it, then the section would not apply since the busduct switch unit (the equipment in that case) does not by itself have a high enough amp rating to trigger the requirement.

If we were talking about an MCC with a 2000A bus going in and only 200A or smaller switch/breaker buckets, then I would say it is clear that the section applies, since nobody (I think) would dispute that the MCC (equipment) contains switches/overcurrent devices and is rated over 2000A.

Another corner case to think about would be what if anything is changed if that MCC with a 2000A bus is fed from a 1000A breaker. :happyyes:
 
It is my opinion that the language in 110.26(C)(2) does not include the busway. I don't see switches that plug into the busway as being contained by the busway.
 
infinity said:
Don, are you saying that the 4000 amp busway doesn't count? (I think that you had something to do with this rule). ;)
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Yes, I am a saying the rating of the busway has nothing to do with the rule. The busway does not CONTAIN the items listed in 110.26(C)(2).
The only thing I had with this rule is that, for one code cycle, I was able to remove the 6' part of the rule.
 
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