Unobstructed Entrance

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rcallen

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Odgen, Utah
Article 110 of the NEC requires extra clearances around switchboards and panelboards whose bus is rated 1200 amps or more. The distance in front must be doubled from table 110.26(A)(1) or there must be two entrances on either end of the switchboard. An exception says that if there is a "continuous and unobstructed way of exit" then two exits/entrances are not required.

What does "unobstructed way of exit mean"? Is a door in front of the switchboard all that is required? Does it mean that the door in front of the switchboard must have panic hardware on it? Does it mean double doors with panic hardware in front of the switchboard? Does it mean an open archway with no doors at all in front of the switchboard?

Is there any consensus on what this requirement means? Does anyone have experience with the interpretations of electrical inspectors that would guide me here?
 

muskiedog

Senior Member
Location
Minnesota
A single entrance to the required working space shall be permitted where either of the conditions in 110.26(C)(2)(a) or (b) is met.
(a) Unobstructed Exit. Where the location permits a continuous and unobstructed way of exit travel, a single entrance to the working space shall be permitted.
(b) Extra Working Space. Where the depth of the working space is twice that required by 110.26(A)(1), a single entrance shall be permitted. It shall be located so that the distance from the equipment to the nearest edge of the entrance is not less than the minimum clear distance specified in Table 110.26(A)(1) for equipment operating at that voltage and in that condition.
 

muskiedog

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Minnesota
So ifyou have two panels face to face the area between would need twice the clearnace distance but then would allow for one exit on the end as long as nothing is in this clearance space.
 

charlie b

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Lockport, IL
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I can't speak from the experience of a person who has debated this question with an AHJ. But my interpretation of "unobstructed" is that a worker with hands inside the equipment can (1) See the door (i.e., the panel cover itself does not obstruct the view, nor does any wall, column, electrical component, or any other thing), and (2) Step back from the equipment and walk straight towards the door, without having to walk around anything.
 

don_resqcapt19

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Illinois
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Reid,
Does it mean that the door in front of the switchboard must have panic hardware on it?
The door(s) for spaces containing electrical equipment rated 1200 amps or more must always have panic hardware and open out. 110.26(C)(2).
Don
 

jim dungar

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Wisconsin
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I am inclined to think that a closed door would be an obstruction, however an open doorway would not be. So if there is a closed door, you need two of them or twice the depth.

I am not sure about the term "continuous". Is the intent that the way of travle must be the entire width or depth as the working space? For example, is it a "continuous way of exit" if you have to move along a wall until you find the doorway?
 

muskiedog

Senior Member
Location
Minnesota
Door not an obstruction

Door not an obstruction

Entrance to Working Space.
(1) Minimum Required. At least one entrance of sufficient area shall be provided to give access to working space about electrical equipment.
(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 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. Where the entrance has a personnel door(s), the door(s) shall open in the direction of egress and be equipped with panic bars, pressure plates, or other devices that are normally latched but open under simple pressure.
 

muskiedog

Senior Member
Location
Minnesota
A single entrance to the required working space shall be permitted where either of the conditions in 110.26(C)(2)(a) or (b) is met.
(a) Unobstructed Exit. Where the location permits a continuous and unobstructed way of exit travel, a single entrance to the working space shall be permitted.
(b) Extra Working Space. Where the depth of the working space is twice that required by 110.26(A)(1), a single entrance shall be permitted. It shall be located so that the distance from the equipment to the nearest edge of the entrance is not less than the minimum clear distance specified in Table 110.26(A)(1) for equipment operating at that voltage and in that condition.
 

charlie b

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Lockport, IL
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Retired Electrical Engineer
jim dungar said:
I am inclined to think that a closed door would be an obstruction. . . . I am not sure about the term "continuous."
I don't see it the same way, and I do think I know what is meant by "continuous."

You are working inside an enclosure. You feel the need to leave quickly. You take your hands out of the enclosure, and drop them to your sides, without touching anything (e.g., you don't first close the enclosure's door or replace the panel cover). You turn your body in the direction of the exit door, and start walking. If you can make it to the panic hardware, without having to walk around a column, and without having to turn left or right, then you have reached the end of the required "way of exit travel."

If you had to walk around a column, the path was obstructed. If you could not see the exit door until you closed the enclosure's cover/door, the path was obstructed. If you came to a wall, and had to turn left before you made it to the exit door, the path was not continuous.

JMHO.
 

jim dungar

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Wisconsin
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charlie b said:
If you came to a wall, and had to turn left before you made it to the exit door, the path was not continuous.

I have never laid out a "small" equipment room so please bear with me. Imagine a working space is 60" deep (front of enclosure to wall) and 120" wide (across the font of the enclosure), no hinged doors on equipment only removable panels.
Scenario 1: 36" wide door mounted in the 60" wall - obstructed exit?
Scenario 2: 36" wide door mounted in the 120" wall - obstructed exit?
 

charlie b

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jim dungar said:
Scenario 1: 36" wide door mounted in the 60" wall - obstructed exit?
jim dungar said:
Scenario 2: 36" wide door mounted in the 120" wall - obstructed exit?
Not enough information is given. Can you stand at the equipment, turn your head, and see the door, and see that nothing is between you and the door? If yes, then "unobstructed." If no, then "obstructed." Again, JMHO.
 

jim dungar

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charlie b said:
Not enough information is given. Can you stand at the equipment, turn your head, and see the door, and see that nothing is between you and the door? If yes, then "unobstructed." If no, then "obstructed."

So, if the equipment is 120" wide and the door is only 36" located toward one end, you feel that it is unobstructed travel as long as the door is visible from everywhere in front of the equipment.

Not trying to put words in your mouth just trying to broaden my knowledge.
 

charlie b

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Lockport, IL
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jim dungar said:
So, if the equipment is 120" wide and the door is only 36" located toward one end, you feel that it is unobstructed travel as long as the door is visible from everywhere in front of the equipment.
Yes. Though perhaps "visible" might not say enough. There must be nothing you would bump into on your way to the door. The mission is to get out of the room.

Nothing I have seen would require the door to be in front of the equipment, nor as wide as the equipment.
jim dungar said:
Not trying to put words in your mouth just trying to broaden my knowledge.
If you base that on my humble opinions, you are placing yourself (and your next submission for Plan Review) at risk. ;) :D
 

jim dungar

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Location
Wisconsin
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PE (Retired) - Power Systems
charlie b said:
If you base that on my humble opinions, you are placing yourself (and your next submission for Plan Review) at risk. ;) :D

It's not that I want to base things on your opinion, its just that you are the only one "discussing" this topic with me.:rolleyes:
 

rcallen

Member
Location
Odgen, Utah
Unobstructed Entrance

OK, what I seem to be hearing is that there is no clear consensus on how we approach this, which is what I suspected.

In the cycles previous to the 2005 NEC there was a dual requirement for the two door requirement: 1200A bus (or higher) and 6 ft. wide switchboard. In the 2005 NEC the 6 ft. wide requirement was removed thus throwing 1200A panelboards into the fray. As it stands at the moment the 2008 NEC will put the 6 ft. wide rule back in, and this will change the discussion some. Of course the final NEC may or may not include this change back, depending on the final vote at the NFPA meeting where the new code is adopted.

In the meantime, it almost seems to come down to "let your conscience be your guide" as to what a "clear and unobstructed" exit path might be.

I appreciate all the contributions to this conversation. Thank you to you all.
 

muskiedog

Senior Member
Location
Minnesota
Okay I am looking at my graphics and the door doesn't need to be directly in front it can be off to the side.

If you can access both sides it would have to be on the end so that you would not have to walk around the equipment to get out or through arcing parts.

1200a or more and over 6 feet wide you would need access panels on both sides you would have to have two entrances at least 24 inches wide and 6 1/2 feet in height.

with just an access to the front of the equipment one unobstructed exit would be allowed.

If you two 1200a in same area face to face but had minimum work clearance doubled you would be able to have one entrance.

Nothing can obstruct the working clearances or path to exit.

Panic hardware on door for 1200A
 
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