measuring electrical clearance

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AlaskaSECM

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It states in NEC Article 110.26(1) Depth of Working Space…is measured from the enclosure front. Now that couldlead you to believe they’re referring to the front enclosure cover. But thenyou see in Figure 110-20 illustrated in blue “Exposed Live Parts.” Table110.26(A)(1) Working Space list 3 Conditions all describing “Exposed LiveParts.” The Article goes on stating Rear and Sides…Work Space isn’t required.

After carefully examining allthese points it is now my interpretation that the statement “is measured fromthe enclosure front” does not indicate the front enclosure cover, butthe “Exposed Live Parts” located from the enclosure front. I think aclearer way of stating this would be…”is measured from the exposed live partsat the enclosure front.”

What is your interpretationplease?
 
If the live parts are enclosed, such as in a standard panel, it is measured from the front cover.

Distances shall be measured from the exposed live parts or from the
enclosure or opening if the live parts are enclosed.
Click to expand...

If you had live exposed parts, say like an old Frankenstein/knife switch, it would be from the live contacts/terminals.
 
There is no "Figure 110-20" in either the code book or the handbook. So I don't know what you are trying to describe. To me, it is clear that the depth of working space begins at the front cover of the panelboard, and not at the live parts that are inside the enclosure. I am not sure how you are concluding otherwise.
 
work space measurement

work space measurement

What I am referring to regarding where to measure work space from is...
the table 100.26(A)(1) Working Space states:
Condition 1-Exposed live parts on one side of the working space...
Condition 2-Exposed live parts on one side of the working space...
Condition 3-Exposed liver parts on both sides of the working space...

the 3 conditions all state point "A" of the work space clearance is "Exposed live parts" to description of...point "B".
It doesn't describe in the parts are enclosed or covers...see how this needs an official type interpretation?
 
AlaskaSECM said:
What I am referring to regarding where to measure work space from is...
the table 100.26(A)(1) Working Space states:
Condition 1-Exposed live parts on one side of the working space...
Condition 2-Exposed live parts on one side of the working space...
Condition 3-Exposed liver parts on both sides of the working space...

the 3 conditions all state point "A" of the work space clearance is "Exposed live parts" to description of...point "B".
It doesn't describe in the parts are enclosed or covers...see how this needs an official type interpretation?
Click to expand...

Every inspector I have ever had measured from the front cover.

That is the only interpretation I need, I like passing inspections.:)
 
The three conditions refer to the presence of live parts on one side or the other, and does not address their location.. For example, you can get to Condition 3 by installing two 480 volt branch circuit panels on opposite walls, directly across from each other. It is conceivable that two separate electricians can be working on the two panels at the same time, or perhaps one electrician is working on both panels at the same time. With both panel covers removed, you would have exposed live parts on both sides of the working space. According to Table 110.26(A)(1), you need 4 feet of working space. But that table does not tell you that you are measuring the 4 feet from exposed live parts to exposed live parts. It only says you need 4 feet. It is the last sentence of paragraph 110.26(A)(1) (quoted earlier by Jumper) that tells you where to take the measurement. In my example, since we are dealing with branch circuit panels, the live parts are within an enclosure. Therefore, the article tells us to measure from the "opening." There is no "opening" until you remove the cover, so the location of the cover is the location from which you measure working clearance.
 
Agreed--It is from the front of the enclosure cover, not the internal parts
 
AlaskaSECM said:
What I am referring to regarding where to measure work space from is...
the table 100.26(A)(1) Working Space states:
Condition 1-Exposed live parts on one side of the working space...
Condition 2-Exposed live parts on one side of the working space...
Condition 3-Exposed liver parts on both sides of the working space...

the 3 conditions all state point "A" of the work space clearance is "Exposed live parts" to description of...point "B".
It doesn't describe in the parts are enclosed or covers...see how this needs an official type interpretation?
Click to expand...
All three conditions state "work space" which starts at the front of the enclosure when dealing with enclosed items.
 
AlaskaSECM said:
What I am referring to regarding where to measure work space from is...
the table 100.26(A)(1) Working Space states:
Condition 1-Exposed live parts on one side of the working space...
Condition 2-Exposed live parts on one side of the working space...
Condition 3-Exposed liver parts on both sides of the working space...

the 3 conditions all state point "A" of the work space clearance is "Exposed live parts" to description of...point "B".
It doesn't describe in the parts are enclosed or covers...see how this needs an official type interpretation?
Click to expand...
See the answer in post #2.
 
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