unobstructed path

[mshields]

For equipment 1200A and 6 feet long, one of the 110 options in addition to having 2 egresses or double the distance, is an unobstructed path. I've always shyed away from that because I don't know what it means. Does it mean you don't have to go through the clearance space to get to it door. I'm trying to avoid that second door and I definitely won't have double the distance.

Thanks,

Mike

 

[steve66]

The handbook has a pretty good diagram that shows this. If you can walk straight back away from the equipment and out a door, its unobstructed.

The handbook shows the door in the middle of the room opposite the middle face of the equipment.

If the equipment is much wider than 6', and/or if the door is offset from the center, at some point I believe it would no longer be unobstructed.

 

[Carultch]

For equipment 1200A and 6 feet long, one of the 110 options in addition to having 2 egresses or double the distance, is an unobstructed path. I've always shyed away from that because I don't know what it means. Does it mean you don't have to go through the clearance space to get to it door. I'm trying to avoid that second door and I definitely won't have double the distance.

Thanks,

Mike

The way I understand it, if you can walk straight back from the equipment to get to the exit, it counts. However, if you have to walk parallel to the equipment in either direction in an aisle no wider than the requisite workspace, or if you have to walk around another piece of equipment (even with an unobstructed 4 ft wide pathway around it), then you need an exit path to both sides of the person, or double the workspace.

The intent of this rule, is so that a person in an emergency situation can get out, without needing to think "which way do I run again...left or right?". If you run the wrong way, you get trapped. But if the exit is straight back, it is immediately obvious.

 

[mshields]

sounds right

sounds right

Yeah - that's about what I thought too. What's more, the exact wording is "continuous and unobstructed". To me that implies a perfectly straight line from you standing in front of any given piece of equipment, to the egress. If you have to deviate from a straight line, it's not "continuous". i.e. the continuity is broken by your having to jog around something. So you agree?

 

[lielec11]

Yeah - that's about what I thought too. What's more, the exact wording is "continuous and unobstructed". To me that implies a perfectly straight line from you standing in front of any given piece of equipment, to the egress. If you have to deviate from a straight line, it's not "continuous". i.e. the continuity is broken by your having to jog around something. So you agree?

I tend to agree with you and Mr. Carultch's description above. However, I recommend speaking to the local AHJ as each jurisdiction may have different interpretations. If you're worried, I would get in touch with the plans examiner and offer to send them what your plan is for their blessing.

For what it's worth, an AHJ I deal with frequently seems to think that "grouped service disconnects" means all on the same wall. Anything else they will not approve. I tend to think this is a ridiculous requirement as architecture often dictates the size and shape of electrical rooms... but such is life.

 

[infinity]

Mike has a pretty good graphic:

 

[charlie b]

I just had this discussion with a plans reviewer from the Washington State Department of Labor and Industries. I had the 1200 amp panel on the long wall of the room, and it didn't have double the working clearance in front of it. If you were standing in front of the panel and looking at it, the exit door was to your right. L&I's position was that if after you stepped away from the panel you had to walk parallel to the panel to get to the door, then you might be walking through an area where arcing and sparking could be taking place. That is the reason they considered this design not to be unobstructed. I redesigned the room to put the panel on the wall opposite the door, and they approved the design.