Clearances 110.26 ( A) ( 3 )

Davebones

Senior Member
We have a 3 ft x 3 Ft by 6 inch deep operator control box about 4 ft off the floor . Start / Stop indicator lights , flow meter . etc . They want to put a permanent metal cabinet below it that will stick out about a foot in front of it . I say no due to the fact that it sometimes needs to be serviced while energized . My supervisor says don't worry about it that its ok . Who's right ?
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Tell this to your supervisor. When human hand contacts a live electrical wire, the muscles of the hand contract. This can cause the hand to firmly grip the live wire, and prevent the person from letting go. Sometimes the only thing that can allow the person to survive this event is when the body loses complete control of all muscles, and drops towards the floor. The weight of the falling body might, I say might, be enough to pull the hand away from the live wire. But if there is not enough room for the person to fall to the ground, if for example there is a cabinet that is so deep that it blocks the person’s body from falling away from the control box, then that person will die. That is the reason that I, as a design engineer, rigorously defend the space that is reserved for working clearance.

I don’t think the owner of this forum would mind my adding one more thing. I have sat in a classroom, attending Mike Holt’s Grounding and Bonding seminar, and hearing him say that he survived an electrical shock event in exactly the way I described above. He said that he still recalls repeatedly saying to himself, “Let go, you idiot, or you are going to die.” It was only the fact that he fell away from the live wire that allowed him to survive.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
We have a 3 ft x 3 Ft by 6 inch deep operator control box about 4 ft off the floor . Start / Stop indicator lights , flow meter . etc . They want to put a permanent metal cabinet below it that will stick out about a foot in front of it . I say no due to the fact that it sometimes needs to be serviced while energized . My supervisor says don't worry about it that its ok . Who's right ?
If your boss can make a good argument that there is never going to be a requirement to work in the control panel with the power on, than it does not matter. Note that the code does not say anything about whether someone is actually working on it energized, only whether there is a requirement to work on it while energized. if it is optional, the code section clearly does not apply, although it may be a good idea. but good ideas are not enforceable.

Personally, I think the code rule is overly broad, especially now that anyone working near potentially lethal voltages is required to wear insulating gloves.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Proposal 1-196 for the 2011 code was to remove the word required in 110.26(A). The CMP rejected the proposed change, and I submitted a comment to accept the change. The following is the panel response.
1-128 Log #1981 NEC-P01 Final Action: Reject
(110.26(A))
_______________________________________________________________
Submitter: Donald A. Ganiere, Ottawa, IL
Comment on Proposal No: 1-196
Recommendation: This proposal should be accepted.

Substantiation: The issue is the use of the word “require” in the existing text. This word limits the enforcement of the working space rules as there is nothing
that “requires” someone to “examine, adjust, service, or maintain” electrical equipment while it is energized. In fact there are standards and safety rules
that prohibit doing most types of work on energized electrical equipment. The elimination of the word “require” will improve the enforceability of this very
important code rule.

Panel Meeting Action: Reject

Panel Statement: The submitter misunderstands use of the word “require” as it is used in 110.26(A). In this context, “require” means “need”. If it is probable that examination, adjustment, servicing or maintenance will need to be performed on energized equipment, then 110.26 applies.

Number Eligible to Vote: 12
Ballot Results: Affirmative: 12
 

Carultch

Senior Member
Location
Massachusetts
Proposal 1-196 for the 2011 code was to remove the word required in 110.26(A). The CMP rejected the proposed change, and I submitted a comment to accept the change. The following is the panel response.
Do you know of any examples where the "maintain while energized" condition, and therefore 110.26(A), does not need to apply?

I always assume that it applies to all equipment.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Do you know of any examples where the "maintain while energized" condition, and therefore 110.26(A), does not need to apply?

I always assume that it applies to all equipment.
That is how the section reads, but if you read it like that the required kitchen counter receptacles are a violation.
Remember "equipment" is a defined term in the code and includes almost everything.
Equipment. A general term, including fittings, devices, appliances, luminaires, apparatus, machinery, and the like used as a part of, or in connection with, an electrical installation.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Do you know of any examples where the "maintain while energized" condition, and therefore 110.26(A), does not need to apply?

I always assume that it applies to all equipment.
I am inclined to agree that just about any equipment is at some point worked on while energized.

I am not all that sure that it is necessary or required, as opposed to being done for convenience.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
But the CMP statement says the rule applies if such work is "probable".
how does the CMP get to redefine what a word means by such a statement?

In any case, substitution of the word "need" into the provision does not change the meaning all that much. There is almost never a "need" to work on energized equipment. There are almost always ways around doing so.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
how does the CMP get to redefine what a word means by such a statement?

In any case, substitution of the word "need" into the provision does not change the meaning all that much. There is almost never a "need" to work on energized equipment. There are almost always ways around doing so.
There is almost always a need to trouble shoot live.
 

charlie b

Moderator
Staff member
Location
Seattle, WA
So our supervisor says don't worry about it leave the cabinet there !
I would want to get the supervisor to put that into writing. If there is a citation for a code violation, or worse an actual injury, the world has a right to know who is to blame. And the world should not blame you.

 
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