Unobstructed egress in electrical room

[charlie b]

If that were true there would be no such thing as dead end or common path of travel.

OK, thanks for posting an explanation of those two phrases. I can now assert that they are irrelevant to the present discussion. The concept of "egress" is common to the two topics, but there the commonality ends. The NEC is only interested in a person?s ability to safely travel from a point inside the working space of a large piece of equipment to the (for the purposes of this thread) one and only door to the room. The building code (or whatever source you have quoted) is further interested in the person?s ability to safely travel from the other side of that door (or from any other point in the building) to a point outside the building. The requirements are separate and unrelated in any way.

 

[nhfire77]

It appears that MSB3 could potentially 'trap' a person. Imagine a worst case scenario where something blows out of MSB3 to either side of it.

A worker in the corner on the wall opposite the door could be standing there. To exit they'd have to pass through the space the MSB3 access panels would blow out into. In my highly unlikely, made up scenario, an active fault is arcing out of the access panel.

IMO, this is the situation the code section addresses. Seems like its the kind of hazard the unobstructed access and 6' clearance is addressing as well.

Of course if gear access panels are adjacent to the door, it could also block you. I also think this is meant to be avoided, with a minimum clearance to the edge of the exit.

(I'm assuming the location of the access panels for the purpose of discuss).

 

[mgookin]

OK, thanks for posting an explanation of those two phrases. I can now assert that they are irrelevant to the present discussion. The concept of "egress" is common to the two topics, but there the commonality ends. The NEC is only interested in a person?s ability to safely travel from a point inside the working space of a large piece of equipment to the (for the purposes of this thread) one and only door to the room. The building code (or whatever source you have quoted) is further interested in the person?s ability to safely travel from the other side of that door (or from any other point in the building) to a point outside the building. The requirements are separate and unrelated in any way.

Those two phrases came up with respect to "straight line" requirements when someone was saying "continuous" meant "in a straight line" and I said egress does not have to be in a straight line. Nobody has demonstrated the need for straight line, nor has anyone cited Article 110.26 verbatim. The building code does deal with obstructions, projections, continuity, etc. The NEC is subordinate to the building code by reference, but that does not mean inferior. In the absence of the NEC defining the language used in the Article, we defer to the buidling code, and in the absence there, to a dictionary.

What is the verbatim language in the NEC?

 

[sandsnow]

Again, looking at the OP's sketch, and considering a person standing in the working space in front of MSB2, how can you say that the location of MSB3 does not constitute an "interruption" in the path to the door?

I don't consider this set up as having an unobstructed means of egress. I should have mentioned that before. I see it as having a means of egress at each end of the workspace. If you can't around the front of MSB3, you can go around the other side. That's what I mean by horseshoe. Still frustrating for me to type what I mean and say.

The one concept I learned many years ago regarding this is that you always need two ways to go to get out of the workspace. Getting out of the building let alone the room is probably advisable but not required here. Just out of the workspace.

I could draw some diagrams and if thread still active I will this weekend.

 

[Gregg Harris]

(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 (6? 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



(a)

Unobstructed Egress. Where the location permits a continuous and unobstructed way of egress 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 110.26A(1), a single entrance shall be permitted. It shall be located such 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]

. . . I said egress does not have to be in a straight line. Nobody has demonstrated the need for straight line, nor has anyone cited Article 110.26 verbatim.

First of all, thank you Gregg for posting the verbatim language of the relevant article. Secondly, while I will agree that "egress" does not mean the person must be able to walk in a straight line, I continue to submit that "continuous and unobstructed way of egress travel" does mean there can be nothing in the straight line path between the working space and the door.

 

[charlie b]

Let me take my viewpoint one step further. This deviates slightly from the specific installation under discussion. But it should help explain my own interpretation of the code.

Look at the original diagram, and let?s assume for the moment that the one and only switchboard in the room is DSB. Assume the room is otherwise completely empty. Assume that DSB comprises all three blocks in the image, meaning that we are looking at three vertical sections of the same switchboard. Assume that DSB is rated 1600 amps and is a total of eight feet wide. Finally, assume that on the left hand vertical section, the access panel cover is hinged such that it can swing open for only the required minimum of 90 degrees.

If the hinges are on the right side of the panel cover, then while the cover is open and a worker is standing in front of the open section, the panel cover will be to the person?s right, and the person can see (and walk directly to) the room?s door. I would consider that the working space has a continuous and unobstructed way of egress travel. I would conclude that the room?s having only one exit door is code compliant.

However, if the hinges are on the left side of the panel cover, then while the cover is open and a worker is standing in front of the open section, the panel cover will be to the person?s left, and it would block the worker?s ability to see (and walk directly to) the room?s door. I would consider that the working space does not have a continuous and unobstructed way of egress travel, since the panel cover will constitute an obstruction. I would conclude that the room?s having only one exit door is a code violation.

 

[GoldDigger]

One thing that strikes me about this is that if you put in a second exit, even if it too is obstructed, you are in compliance.
Similar to only having to add a second ground rod no matter how high the resistance of each of them is.

Tapatalk!

 

[jim dungar]

I would conclude that the room?s having only one exit door is a code violation.

The NEC does not care how many exits you have from the room.

The quoted NEC section deals with "required working space". You must be able to leave the working space, leaving the room becomes a 'design' or other building code issue

So if the hinged door is opened, has the 'required working space' changed?
Have you left the working space by stepping sideways so you are no simply longer 'in front' of the gear?

 

[Gregg Harris]

The NEC does not care how many exits you have from the room.

The quoted NEC section deals with "required working space". You must be able to leave the working space, leaving the room becomes a 'design' or other building code issue

So if the hinged door is opened, has the 'required working space' changed?
Have you left the working space by stepping sideways so you are no simply longer 'in front' of the gear?

?

 

[charlie b]

The NEC does not care how many exits you have from the room. The quoted NEC section deals with "required working space". You must be able to leave the working space, leaving the room becomes a 'design' or other building code issue

I have been down this road before. The NEC is not clear on this issue, and the attempt to clarify it in the 2011 version didn't work.

Consider a piece of "large equipment" that requires 4 feet of working space. Suppose there were 6 feet of open space in front of the board. Suppose you are standing facing the board, with the heels of your shoes right at the 4 foot distance. One could say that you can safely egress from the working space by taking one step backwards. So does that satisfy the code requirements? Well, if that were the case, then why would there be a rule about having double the working space? Also, why would the 2011 have added a discussion about the egress from the working space being a door within 25 feet? As I say, the code is not clear about what it means by egress from the working space.

 

[jim dungar]

Consider a piece of "large equipment" that requires 4 feet of working space. Suppose there were 6 feet of open space in front of the board. Suppose you are standing facing the board, with the heels of your shoes right at the 4 foot distance. One could say that you can safely egress from the working space by taking one step backwards. So does that satisfy the code requirements? Well, if that were the case, then why would there be a rule about having double the working space? Also, why would the 2011 have added a discussion about the egress from the working space being a door within 25 feet? As I say, the code is not clear about what it means by egress from the working space.

Access to some workspaces is through a door way, such as an equipment vault, but in other cases the gear is in a room that is many multiples of the working space in size.

Simply stepping out of the working space is not sufficient, the code clearly requires you to be able to exit to an area that results in at least 2 times the depth of the working space (maybe this is to provide for the open panel/door on the gear).

My guess is the 25' distance is so someone doesn't 'get trapped' simply due to distance. Over the years I have had the opportunity to stand in front of many MCC lineups, or behind unit substations, that created tunnels well over 25' in length.

For your example, if the equipment requires 4 feet of clearance and it is located in a room that provides 26' clearance, do we need to build a wall and add a doorway due to the 25' limitation?

 

[GoldDigger]

If the wall and doorway form a fire barrier, it might make sense to do just that.

Tapatalk!

 

[mgookin]

It looks like the codes (bldg & elec) are consistent with the language "continuous and unobstructed".

Defintion:
MEANS OF EGRESS. A continuous and unobstructed path of vertical and horizontal egress travel from any occupied portion of a building or structure to a public way. A means of egress consists of three separate and distinct parts: the exit access, the exit and the exit discharge.

I think we can agree that an electric room is an "occupied portion of a building or structure" which needs egress.

As to obstructions, a door in any part of its swing may not reduce the required width of a corridor, aisle, etc. more than 1/2 the required width of that corridor, aisle, etc. And in the fully open position, a door may not encroach more than 7" into that required width. An open access panel certainly is an "obstruction" whether it's a door or not. And there's a whole lot more in the code about obstructions both veritical and horizontal dealing with everything from fire extinguisher cabinets, drinking fountains, posts & bollards, signage, etc.

The electric code in Article 110.26 deals with two things:
1) Working space at electrical equipment, and,
2) Number of exits from an electric room.


Access panels for electric equipment are required to open 90 degrees minimum. This puts you in the situation charlie b describes above.

In my opinion (take that for what it's worth) if you have a requirement for 42" working space, that open access panel can encroach that entire 42", or more, but that does not relieve you of the requirement to have an egress aisle from that "occupied portion of a building or structure" which is outside of the area obstructed by the open access panel. You still have to have and continuously maintain an egress aisle.

Next thing to consider: Are all access panels deemed to be open concurrently? It certainly is logical that they may be. Imagine a room that's a tunnel with equipment both sides. The width of that room has to be the aggregate with of all equipment, all access panels open, plus the required egress aisle width. You can't trap workmen in the room by having access panels open as charlie b describes.

Make sense?

 

[jim dungar]

You can't trap workmen in the room by having access panels open as charlie b describes.

So shouldn't tool boxes, test equipment, and step stools also be prevented from being used in working spaces, if they restrict egress?

 

[mgookin]

So shouldn't tool boxes, test equipment, and step stools also be prevented from being used in working spaces, if they restrict egress?

Those are not permanent installations. They are not part of the building.

 

[greenspark1]

I wonder why the Code has additional egress requirements only if equipment is over 1200A AND 6' wide. There are lots of switchgear 3-5' wide that handle thousands on amps. I'd certainly want an unobstructed escape route when working on the gear!

PS- Back to the original post- the new panel clearly obstructs the egress route to the door. If there was an incident with fire and/or smoke you want a clear way out of that room, without a panel in the way.

 

[charlie b]

I think we can agree that an electric room is an "occupied portion of a building or structure" which needs egress.

Sorry, but we can't agree on that point. A room that occasionally has a person inside is not "occupied," in the context of that word as used by the building code. That word implies that the area is someone's normal work space.

 

[mgookin]

Sorry, but we can't agree on that point. A room that occasionally has a person inside is not "occupied," in the context of that word as used by the building code. That word implies that the area is someone's normal work space.

No problem. I can agree to disagree any day. How about the guy using the restroom? Often that's the longest travel distance in a floor plan. I never heard of a ground floor or otherwise readily accessible electrical or mechanical room being exempt from building code chapter 10 egress requirements. Equipment platforms and mezzanines yes, but not a room dedicated for the purpose.

 

[charlie b]

I suggest leaving the building codes out of this discussion. Yes, the NEC uses the word "egress." Yes, the building codes use that same word. But the two uses are unrelated in any way. There are also other words that appear in both the NEC and the building codes, and here again the two sets of meanings are separate, distinct, and unrelated to each other. Once you have made your way safely out of the working space (and some would argue you need to be able to exit the room as well, but let's save that discussion for another time), the NEC stops using the word "egress," and stops caring where you go. The building codes would have you be able to also breath outside air, and they provide rules for egress paths leading outside the building. The word "egress," in the context of exiting the building, means nothing to the NEC.