Article 110 clearance requirements

[mshields]

A colleague of mine has encountered a client who believes that a handle protruding out the face of an ATS/with Bypass; i.e. the furthest part of that handle protruding from the front surface of the ATS enclosure, is the point from which you have to measure the 4 feet to the 480V equipment opposite it.

I'm confident that the clearance is from the front surface to the front of the opposite piece of equipment, regardless of any kind of breaker handles or in the example sited above, handles for putting the ATS into bypass.

Can anyone tell me where I would find the relevant verbiage in the NEC?

Thanks,

Mike

 

[don_resqcapt19]

"110.26(A)(1) ... Distances shall be measured from the exposed live parts or from the enclosure or opening if the live parts are enclosed."

However, it is my opinion that the handles on the equipment on the opposite side of the aisle mark the end of the workspace. You measure from the face of this equipment to the handle on the equipment that is opposite.

 

[Gary11734]

A colleague of mine has encountered a client who believes that a handle protruding out the face of an ATS/with Bypass; i.e. the furthest part of that handle protruding from the front surface of the ATS enclosure, is the point from which you have to measure the 4 feet to the 480V equipment opposite it.

I'm confident that the clearance is from the front surface to the front of the opposite piece of equipment, regardless of any kind of breaker handles or in the example sited above, handles for putting the ATS into bypass.

Can anyone tell me where I would find the relevant verbiage in the NEC?

Thanks,

Mike

It would make sense that the handle would be part of the clearance since it could keep you (the worker) from actually getting the clearance the code refers to.

 

[victor.cherkashi]

I don't see in NEC how to measure if there is handle. at the same time word - clearance - could mean no objects shall be in this area. if the handle/object 1 ft do we still need to measure from enclosure. probably if the handle is easily removable, you can convince the inspector it's not part of the clearance.

Sent from my ONEPLUS A6013 using Tapatalk

 

[kingpb]

In the true sense of definition and application, the handle protruding, if metal, would be a grounded surface and thus would have to be considered in the distance measurement.

 

[Strathead]

"110.26(A)(1) ... Distances shall be measured from the exposed live parts or from the enclosure or opening if the live parts are enclosed."

However, it is my opinion that the handles on the equipment on the opposite side of the aisle mark the end of the workspace. You measure from the face of this equipment to the handle on the equipment that is opposite.

This is interesting and tough. My opinion is that one would have to defer to the Authority, but any authority that decided it was from the face of the handle would be petty. Common sense tells me that the reason the code is written that way is to allow the worker adequate moving around room from where his body and his feet need to be. So even if an enclosure is deep, the worker still needs clearance outside the equipment because that is where he is going to be residing. Given that, the handles on the face would not be protruding, because the face would be removed. Also, in my opinion, a handle or a pilot light would not be "enclosure" they would be "accessories" but the code doesn't specifically state the accessories aren't part of the enclosure so it is hard to actually argue.

 

[infinity]

In the true sense of definition and application, the handle protruding, if metal, would be a grounded surface and thus would have to be considered in the distance measurement.

That's true but the distance to a grounded surface for above 150 volts to ground is 6" less than live parts on both sides so it likely won't matter.

 

[charlie b]

I first thought this was going to be a “no brainer.” Now I realize that it is a “lots of brainer.”

Since you mentioned 480 volts and 4 feet, it is clear that you are considering the situation under “Condition 3.” You have a 480 volt something or other opposite an ATS, both of which have the possibility of requiring live work. It is not inconceivable that both could require live work at the same time. So yes, Condition 3 would apply here.

HOWEVER,

• IF both have their enclosures open for inspection or maintenance, then the handle will have been removed. So if there is 4 feet from enclosure front to enclosure front, you are code compliant.
• IF ON THE OTHER HAND the ATS is not undergoing inspection or maintenance when the 480 volt something or other is requiring live work, then the handle is just another grounded surface. That puts you into Condition 2. Therefore, all you would need is 3’-6” between the front of the 480 volt enclosure and the handle of the ATS.

Interesting question, Mike.

 

[Strathead]

I first thought this was going to be a “no brainer.” Now I realize that it is a “lots of brainer.”

Since you mentioned 480 volts and 4 feet, it is clear that you are considering the situation under “Condition 3.” You have a 480 volt something or other opposite an ATS, both of which have the possibility of requiring live work. It is not inconceivable that both could require live work at the same time. So yes, Condition 3 would apply here.

HOWEVER,

• IF both have their enclosures open for inspection or maintenance, then the handle will have been removed. So if there is 4 feet from enclosure front to enclosure front, you are code compliant.
• IF ON THE OTHER HAND the ATS is not undergoing inspection or maintenance when the 480 volt something or other is requiring live work, then the handle is just another grounded surface. That puts you into Condition 2. Therefore, all you would need is 3’-6” between the front of the 480 volt enclosure and the handle of the ATS.

Interesting question, Mike.

One observation. Each of us thinks differently. When I thought of a handle my thought is some sort of phenolic handle like a breaker handle or a MCC handle. So,, I had to reconsider to even think of like a metal disconnect handle, so even they have an insulated tip, so ground to ground distance would still have to be to the metal.

 

[Chamuit]

Isn't this talking about the working clearance and not operating clearance?

 

[Strathead]

Isn't this talking about the working clearance and not operating clearance?

Yes, but what is the point you are getting at?

 

[Chamuit]

Yes, but what is the point you are getting at?

The code requirement may not be adequate for operating but suitable for working.