NEC 110.26(A)(2) - Width of Working Space

[KeithAdams]

The width of working space can be shared between electrical equipment. My question is, in order for the width of the working space to be shared, does all the equipment need to be front aligned? For example, for the working space above and below, electrical equipment can protrude up to 6".

Here is the situation...you have a disconnect switch and standard panel mounted side-by-side on a wall. The disconnect switch extends 8" from the rear wall with 28" from the side wall to the edge of the panel. The panel extends 10" from the rear wall and 50" from the side wall. Can these two pieces of equipment share the working space?

 

[infinity]

The 6" rule is only for a projection under the equipment.

 

[GoldDigger]

As long as the 10" panel does not interfere with opening the door or operating the handle on the 8" disconnect, I doubt than any inspector would call you on it.
If there had been enough clearance total counting both sides of the 8" disconnect and there is no opening interference you can put a deeper panel or device as close as you want to the 8". The 28" space between side wall and panel rules that out though.
If you space the disconnect out 2" from the wall you would be totally complaint to the pickiest inspector IMHO.

 

[Carultch]

The width of working space can be shared between electrical equipment. My question is, in order for the width of the working space to be shared, does all the equipment need to be front aligned? For example, for the working space above and below, electrical equipment can protrude up to 6".

Here is the situation...you have a disconnect switch and standard panel mounted side-by-side on a wall. The disconnect switch extends 8" from the rear wall with 28" from the side wall to the edge of the panel. The panel extends 10" from the rear wall and 50" from the side wall. Can these two pieces of equipment share the working space?

If you have multiple pieces of equipment of dissimilar depths, simply take the worst case scenario depth, and extend the 110.26 depth behind it.


So if you have an 8" deep disconnect, and a 10" deep panelboard, and suppose you need 36" depth of working space. This means that you'd need a 30" wide x 46" deep space in front of the finished wall surface, to mount these two pieces of equipment adjacent to one another and share their combined work space.

 

[Carultch]

The width of working space can be shared between electrical equipment. My question is, in order for the width of the working space to be shared, does all the equipment need to be front aligned? For example, for the working space above and below, electrical equipment can protrude up to 6".

Here is the situation...you have a disconnect switch and standard panel mounted side-by-side on a wall. The disconnect switch extends 8" from the rear wall with 28" from the side wall to the edge of the panel. The panel extends 10" from the rear wall and 50" from the side wall. Can these two pieces of equipment share the working space?

I've attached an image that shows two ways to satisfy the workspace width requirement, in a scenario such as yours. I'm assuming an application with a 36" depth requirement.

 

[GoldDigger]

If you have multiple pieces of equipment of dissimilar depths, simply take the worst case scenario depth, and extend the 110.26 depth behind it.


So if you have an 8" deep disconnect, and a 10" deep panelboard, and suppose you need 36" depth of working space. This means that you'd need a 30" wide x 46" deep space in front of the finished wall surface, to mount these two pieces of equipment adjacent to one another and share their combined work space.

An interesting idea, but taken to the extreme, that does not hold up:
Suppose my 8" deep disconnect is also 8" wide. If I put it between a wall and a 36" deep, 48" wide panelboard, with an inch of clearance on either side. Then no matter how much space I provide in front of the 36" deep panel I do not have the working space I need for the disconnect.
At some point the adjacent equipment sticks out far enough that it restricts the working space for the equipment closer to the wall. The NEC does not seem to specify that distance, potentially leaving us with a zero tolerance rule.

 

[infinity]

I've attached an image that shows two ways to satisfy the workspace width requirement, in a scenario such as yours. I'm assuming an application with a 36" depth requirement.

The 8" equipment on the far left of you graphic would require 30" of width in front of it.

 

[Carultch]

An interesting idea, but taken to the extreme, that does not hold up:
Suppose my 8" deep disconnect is also 8" wide. If I put it between a wall and a 36" deep, 48" wide panelboard, with an inch of clearance on either side. Then no matter how much space I provide in front of the 36" deep panel I do not have the working space I need for the disconnect.
At some point the adjacent equipment sticks out far enough that it restricts the working space for the equipment closer to the wall. The NEC does not seem to specify that distance, potentially leaving us with a zero tolerance rule.

Right. I suppose if you have that tiny disconnect between two transformers that are each a square yard in footprint, it would definitely not seem to have its work space, and it would be impractical to access it safely.

My example doesn't particularly look to be unsafe, but you are right that the NEC does seem to give a zero tolerance on this by omission. I would think that if a wire trough can stick out up to 6", then any other electrical equipment would be able to do the same. There also is equipment that comes from the factory with a non-uniform depth, such as SMA Sunny Boy inverters. Is it a problem that their wiring cabinet is only 7" deep, while the inverter main body is 10" deep?

Also, another issue is structural features penetrating the work space such as housekeeping slabs on floor-mounted equipment. You probably would design these with some excess concrete beyond the equipment footprint, possibly up to 6". Although by omission, the NEC leaves us with a zero tolerance policy on this.

 

[Carultch]

The 8" equipment on the far left of you graphic would require 30" of width in front of it.

So what you are saying, is you'd have to either solve it with one of the following solutions?

 

[GoldDigger]

Is it a problem that their wiring cabinet is only 7" deep, while the inverter main body is 10" deep?

IMHO, no, as long as it is one single piece of equipment.
But applying the same exaggeration to that as to my other example, then at some point it becomes unsafe or unusable even if the NEC does not care.
Possibly that sort of clearance issue is the proper subject of UL listing for the equipment?

 

[infinity]

So what you are saying, is you'd have to either solve it with one of the following solutions?

Yes, the two pieces of equipment would need to be aligned at the front for them to share the required work space. Your 2" build out on the shallower depth equipment makes it complaint.

 

[jaggedben]

Yes, the two pieces of equipment would need to be aligned at the front for them to share the required work space. Your 2" build out on the shallower depth equipment makes it complaint.

And in your opinion is his other option (on the right of the drawing) compliant? Overlapping but separately figured work spaces?

Most AHJs around here do not require the 30" wide space to be centered upon the equipment. Except the one we had an inspection in on Friday. :slaphead:

 

[GoldDigger]

And in your opinion is his other option (on the right of the drawing) compliant? Overlapping but separately figured work spaces?

Most AHJs around here do not require the 30" wide space to be centered upon the equipment. Except the one we had an inspection in on Friday. :slaphead:

IMHO the one on the right in post #9 is unconditionally allowed except possibly by shirt pocket code.
And FW little IW the Handbook seems to agree.

 

[infinity]

And in your opinion is his other option (on the right of the drawing) compliant? Overlapping but separately figured work spaces?

Most AHJs around here do not require the 30" wide space to be centered upon the equipment. Except the one we had an inspection in on Friday. :slaphead:

Both depictions in post #9 are code complaint.