Access to Working Space or to Room

[QC101]

Access to large equipment.

I work for a general contractor on a project to design/construct a dining facility for the government. I am involved in an interesting question regarding access/egress for large equipment. One party says the electric code requires two doors in the electric room in order to satisfy code requirements for large equipment. A different party makes the following argument:

Paragraph 110.26(C)(2) of the NEC states:

"(C) Entrance to Working Space

(1) Minimum Required. At least one entrance of sufficient area shall be provided to give access to and egress from working space about electrical equipment.

(2) Large Equipment. For equipment rated 1,200 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 (6? ft.) high at each end of the working space."

It is important to understand that the code is referring to ?working space? as defined by Paragraph 110.26(A), and not a ?room?. The working space for any piece of electrical equipment in Electrical Room 224 extends 36? (for 208/120V) or 42" (for 480/277V) from the face of the equipment in order to comply with Condition 2 of Table 110.26(A)(1). The attached sketch shows the working space of Main Switchboard ?MSB? highlighted in yellow. [Although only ?MSB? is shown highlighted, this procedure and reasoning also works for every other piece of electrical equipment in this room.] As you can see, the ?working space? about each piece of electrical equipment has entrances and exits at each end.

Being a new poster, I could not post the sketch that would clarify the above description. The electric room is 20' x 20' with one double door centered on one wall. The other walls have equipment. There is a transformer in the center of the room with at least 6' clearance on all sides.

I would be interested in how others interpret this problem.

 

[ptrip]

Access to large equipment.

I work for a general contractor on a project to design/construct a dining facility for the government. I am involved in an interesting question regarding access/egress for large equipment. One party says the electric code requires two doors in the electric room in order to satisfy code requirements for large equipment. A different party makes the following argument:

Paragraph 110.26(C)(2) of the NEC states:

"(C) Entrance to Working Space

(1) Minimum Required. At least one entrance of sufficient area shall be provided to give access to and egress from working space about electrical equipment.

(2) Large Equipment. For equipment rated 1,200 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 (6? ft.) high at each end of the working space."

It is important to understand that the code is referring to ?working space? as defined by Paragraph 110.26(A), and not a ?room?. The working space for any piece of electrical equipment in Electrical Room 224 extends 36? (for 208/120V) or 42" (for 480/277V) from the face of the equipment in order to comply with Condition 2 of Table 110.26(A)(1). The attached sketch shows the working space of Main Switchboard ?MSB? highlighted in yellow. [Although only ?MSB? is shown highlighted, this procedure and reasoning also works for every other piece of electrical equipment in this room.] As you can see, the ?working space? about each piece of electrical equipment has entrances and exits at each end.

Being a new poster, I could not post the sketch that would clarify the above description. The electric room is 20' x 20' with one double door centered on one wall. The other walls have equipment. There is a transformer in the center of the room with at least 6' clearance on all sides.

I would be interested in how others interpret this problem.

The transformer in the middle of the room sounds like the sticky point.

You're whole room is electrical working space and your exit from the working space requires getting through the door. Escaping the working space of one piece of equipment by going into the working space of another piece of equipment during an incident is not at all desirable. You just never know when an arc of one piece of equipment can cause failure in another (I'm paranoid that way).

If the transformer didn't exist in the middle of the room (mounted on supports from the ceiling structure maybe with plenty of head clearance maybe?), then the single set of double doors would meet 110.26 (C)(2)(a) with no issue.

Is there a chance that you could scoot the transformer around to acheive the double clearance required by 110.26(C)(2)(b)?

Pam

 

[charlie b]

It is clear from the text you quoted that you are working under the 2008 NEC. Article 110.26(C)(3) was added in 2008. It tells me that a door can be the entrance to the working space, even though the door is 25 feet away from the edge of the equipment. I believe that disproves the argument put forth by the party who thinks one door to the room is enough.

Welcome to the forum.

 

[weressl]

It is clear from the text you quoted that you are working under the 2008 NEC. Article 110.26(C)(3) was added in 2008. It tells me that a door can be the entrance to the working space, even though the door is 25 feet away from the edge of the equipment. I believe that disproves the argument put forth by the party who thinks one door to the room is enough.

Welcome to the forum.

This is where the question comes in: all the access requirements were established on live work. As live work becomes ruled out due to the available energy levels and employers are becoming reluctant to allow it, will there be a time when they will step forward to reduce these space requirements? Expecially in commercial environment where this space can't earn the $1000/sqft. rental fee?

I just love - not - playing the devils advocate tonight.