NEC 110.26

[Isaiah]

Does a 480VAC, non-fused (vs fused) disconnecting means in any way preclude the parameters set forth by110.26 for min working clearances?

 

[don_resqcapt19]

Not in my opinion. Non-fused disconnects are often places where a troubleshooter will check for voltage, and checking for voltage is "examination" of that equipment in 110.26(A).

 

[augie47]

Question comes up here relatively often and it always falls back to the wording " Working space for equipment operating at 1000 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized "
At times the argument is made, but I have not met an inspector that does not agree with don.

 

[petersonra]

Does a 480VAC, non-fused (vs fused) disconnecting means in any way preclude the parameters set forth by110.26 for min working clearances?

I don't think it matters much if it is fused or nonfused. The disconnect is either "likely to require examination, adjustment, servicing, or maintenance while energized", or it is not. Since the code does not define what the word "likely" means, it is upto the dictionary to define it. The dictionary definition that most fits this situation means that such an event is probable.

One can make a good argument that at some point in the life of the equipment it is probable that someone will examine it while energized.

This is another piece of bad code writing that should have been revisited a long time ago for certain things like terminal boxes and disconnect switches. The thing is that most places do not worry about working space for terminal boxes but chances are someone will be in there while it is energized on a regular basis for debugging purposes. Yet no one seems to care about that.

Or about peckerheads. Half the time you can't even get into them without standing on your head.

 

[Isaiah]

I don't think it matters much if it is fused or nonfused. The disconnect is either "likely to require examination, adjustment, servicing, or maintenance while energized", or it is not. Since the code does not define what the word "likely" means, it is upto the dictionary to define it. The dictionary definition that most fits this situation means that such an event is probable.

One can make a good argument that at some point in the life of the equipment it is probable that someone will examine it while energized.

This is another piece of bad code writing that should have been revisited a long time ago for certain things like terminal boxes and disconnect switches. The thing is that most places do not worry about working space for terminal boxes but chances are someone will be in there while it is energized on a regular basis for debugging purposes. Yet no one seems to care about that.

Or about peckerheads. Half the time you can't even get into them without standing on your head.

Thanks for the great feedback! Agreed.
Would another reason for maintaining the distances be potential Arc-Flash scenario when closing/opening the switch?


Sent from my iPhone using Tapatalk

 

[petersonra]

Thanks for the great feedback! Agreed.
Would another reason for maintaining the distances be potential Arc-Flash scenario when closing/opening the switch?


Sent from my iPhone using Tapatalk

Not imo.

 

[Carultch]

On the subject of 110.26, how is it supposed to work with the imprecise metric conversions?

For instance, 3'-6" is a lot different than 1 meter, yet 110.26's table provides these values as if they were equivalents. This is a significant inconsistency, that 40" would fail by the inch standard, and pass by the metric standard. And this is not an oversight, because this example used to specify 1.07 meters in NEC2014, which is much closer to 42".

How is this supposed to work? Is there a standard rule that permits an installation that complies with either the inch or metric dimension, whichever is more permissive?

 

[don_resqcapt19]

On the subject of 110.26, how is it supposed to work with the imprecise metric conversions?

For instance, 3'-6" is a lot different than 1 meter, yet 110.26's table provides these values as if they were equivalents. This is a significant inconsistency, that 40" would fail by the inch standard, and pass by the metric standard. And this is not an oversight, because this example used to specify 1.07 meters in NEC2014, which is much closer to 42".

How is this supposed to work? Is there a standard rule that permits an installation that complies with either the inch or metric dimension, whichever is more permissive?

Take a look at 90.9(D).

(D) Compliance.
Conversion from inch-pound units to SI units shall be permitted to be an approximate conversion. Compliance with the numbers shown in either the SI system or the inch-pound system shall constitute compliance with this Code.