working space clearances

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vanetten

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I have an existing roof top AHU with heat pipes that run approx. 1' to 2' in front of the disconnect switch and service panel.

110-26A states that dimensions per table 110-26a must be met for servicing or maintenance while the equipment is energized.

If I de-energize the unit from its source, which is in the basement, is this in violation?
 
Re: working space clearances

vanetten said:
110-26A states that dimensions per table 110-26a must be met for servicing or maintenance while the equipment is energized.
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It is a subtle point, but that is not what 110.26 states. What it states is that working clearance must be maintained for any electrical equipment that is "likely to require examination, adjustment, service, or maintenance while energized."

Today, you may deenergize the equipment to replace a filter. Tomorrow you might not deenergize the equipment, because you need to use a voltmeter to figure out why the equipment is not working. Whatever your intentions, it is commonly held that most types of equipment, and this absolutely includes breaker panels and A/C equipment, are "likely" to require, at the very least, examination while energized. Even if it is never actually worked on live, it is still "likely" to require live work.

So I would call the situation you have described (1) A code violation, and more importantly (2) So unsafe that steps should be taken to correct the issue.
 
IMO As long as you keep a lock on it so that it cannot be re energized it is legal. Some of the trouble shooting on those units is hard to do with the power off.
Consequently, IMO it is not code compliant for working distances. :)
 
I submitted a proposal to the 2008 NEC to clean-up this section however it was rejected. Here is the statement by the CMP.

Removing ?likely to require examination, adjustment, servicing, or maintenance while energized ? is over-restrictive. CMP-1 understands the submitter?s concerns about the use of vague or unenforceable language. The NEC Style Manual, however, recognizes and prefers the use of the term ?likely? over the term ?liable.? As an example, ?likely to become energized? means ?failure of insulation on.? Although the NEC Style Manual discourages the use of the term ?likely?, there are instances where the use is appropriate.
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I've always found 110.26 to be kind of an conundrum when it applies to AHU, Fan Power Boxes, etc. installed above hung ceilings. These things will at some point require testing or maintenance while energized but the working space requirements seemingly can never be met. How do we allow an above ceiling installation that is surrounded by conduit, cables, duct work, ceiling supports, building steel, etc. to be compliant yet we would violate the installation that is mentioned in the OP. If one were to choose which of these two installations that they would rather work on energized wouldn't everyone choose the AHU with the pipe within 1-2'?
 
thanks guys for the replys. So if the disconnect switch gets moved to the other side of the ahu, but the access panel still dont have the clearance then this is still in violation?
 
you have a point infinity. What about disconnects for dryers and dishwashers? This code tells me that I need a 3' working space. How is that possible? There has to be some exception for certain equipment.
 
vanetten said:
. . . but the access panel still doesn't have the clearance then this is still in violation?
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Yes. And it is still dangerous. I will also concede that it would not be easy to fix. This sort of thing should be prevented before construction, not left to be fixed afterwards.
 
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