Equipment spacing requirements 110.26a2

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Bob Anchorite

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On page 47 of the 2005 NEC yellow handbook is the following:

Imagine 3 panelboards side by side against a back wall
in this order PB-a PB-b Pb-c

Exhibit 110.12 (a plan drawing of a room with three panelboards side by side. Now according to what we would normally think there should be 30" inches between each panelboard's adjacent edge), but the handbook drawing shows the 30" to be from the leftside of the PB-a to the approx middle of PB-b.

The note below the drawing says..." The 30" wide front working space, which is not required to be directly centered on the electrical equipment if space is sufficient for safe operation and maint. of such equip."

THis seems a bit vague and confusing. So please explain this more clearly??
 
You need a minimum space of 30" to work, that 30" space for one panel can and often does intrude into the work space of the next panel.

If I have three 20" wide panels installed touching each others sides I need a total work space of 60" (3 x 20" = 60")

I don't need 90" of workspace. (3 x 30" = 90")
 
Bob Anchorite said:
THis seems a bit vague and confusing. So please explain this more clearly??
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Try this "explaination":

The 30" requirement is NOT for the panelboard - it is for the person whom will be working ON the panel.

Below is copied from the 2002 NECH:
Regardless of the width of the electrical equipment, the working space cannot be less than 30 in. wide. This allows an individual to have at least shoulder-width space in front of the equipment. This 30-in. measurement can be made from either the left or the right edge of the equipment and can overlap other electrical equipment, provided the other equipment does not extend beyond the clearance required by Table 110.26(A)(1). If the equipment is wider than 30 in., the left-to-right space must be equal to the width of the equipment. See Exhibit 110.10 for an explanation of the 30-in. width requirement.
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Note: 2002 NECH Exhibit 110.10 shows 3 Panels aligned on a wall that is 60" +/- wide.....probably the same image as Exhibit 110.12
 
The 30 " clearance is in regards to, having nothing under or in front of the panel for 30 ".If you can measure from either side or centered and have no obstruction there for 30 ".Then the rule has been met as long as back clearance has also been met.
 
Bob Anchorite said:
The note below the drawing says..." The 30" wide front working space, which is not required to be directly centered on the electrical equipment if space is sufficient for safe operation and maint. of such equip."
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Bob Anchorite said:

This seems a bit vague and confusing. So please explain this more clearly??
Click to expand...


The ?not required to be directly centered? part comes into play when you have an enclosure that is less than 30 inches wide. Let?s talk about one that is only 12 inches wide.

Suppose you want to install in an area that only has 30 inches of space on the wall. Suppose you want to install it on the far left side of that space. If you do, counting from left to right, you will have no space to the left of the enclosure, then 12 inches of space occupied by the enclosure itself, and finally 18 inches of space to the right of the enclosure. That totals 30 inches, and you are OK.

What the rule is saying is that you don?t have to put the enclosure in the center, such that you have 9 inches to the left of the enclosure and 9 inches to the right.
 
Charlie what`s your take on a situation where you have side by side panels lets say.One is 3 1/2 ins. deep and the one next to it is lets say 5 1/2 ins. deep.To the right of the 3 1/2 in panel is a wall so your measurment has to start from the right edge but in that measurement of 30 in. the 5 1/2 in. deep panel encroaches the 30 in. space.IMO that would be a violation since the 30 in measurment of the shallower panel is now encroached by the deeper panel.This is a surface mounted scenario .
 
110.26(A)(3)

(3) Height of Working Space The work space shall be clear and extend from the grade, floor, or platform to the height required by 110.26(E). Within the height requirements of this section, other equipment that is associated with the electrical installation and is located above or below the electrical equipment shall be permitted to extend not more than 150 mm (6 in.) beyond the front of the electrical equipment.
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Roger
 
Not so fast, Roger. Allenwayne's question had to do with two panels side by side, not one above the other. So the rules about the height of the working space do not come into play.

I agree with Allenwayne's earlier statement that the situation he described would be a violation.
 
Guess I read to quickly.The height requirement wouldn`t come into play in this side by side senario.I have always been under the understanding that the working clearance, is an area that nothing in front of the panel being measured can extend beyond the front of the shallowest point of the panel being measured.This is on surface mounted equiptment.
 
I think a reasonable reading of 110.26(A)(2) would permit the intrusion of the deeper panel if it didn't interfere with 90 degree opening of doors or hinged panels. It certainly doesn't violate the "room for the shoulders" principle. The available depth would have to be measured from the face of the most protruding panel.
 
Bob NM you make a good point.the article does say as long as the door can be opened 90 degrees the install is fine.Calgon take me away..... Isn`t that a blast from the past ......
 
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