Working Clearance

[jglavin427]

2014 NEC. We had a discussion about working clearances related to disconnects. The language in 110.26(A) "likely to require examination, adjustment, servicing or maintenance while energized" led some of my colleagues to question the existing installation at our facility.

We have a conveyer belt system with catwalks along most of the belts, and each belt drive motor has an associated disconnect next to it mounted on the side where the catwalk is. All drives are 480V 3Ph. If it meets the requirements of 110.26(A) then 42 inches are required in front. Catwalks are only 29 inches wide. My contention was that having the disconnect precludes the motors from meeting that requirement, and the disconnect itself is not likely to require servicing so it too is code compliant as installed.



There is a large project coming up to upgrade and extend the conveyers and everyone wants to avoid a disaster in permitting if it turns out the catwalks need to be widened (would be a huge and expensive endeavor).

 

[augie47]

There is obviously some room for discussion with the wording however I feel most inspection authorities would consider the pictured switch as subject to the 110.26 requirements

 

[greenspark1]

Interesting problem and good photo to illustrate the point. Two thoughts:

1) Locate the motor disconnects in a central location within sight of the motors and provide the 42" of clearance as required. If in sight isn't practical meet 430.102 (B) exception b for industrial locations.

2) The opening paragraph of 110.26 requires all electrical equipment to have access and working space. Also, if you only check for voltage at the motor disconnect you need the full 42". I think proving you won't need to check voltage will be difficult.

 

[jglavin427]

There is obviously some room for discussion with the wording however I feel most inspection authorities would consider the pictured switch as subject to the 110.26 requirements

That's what the belt guys think, too; I tend to disagree but as you say, there's room for interpretation.
What if we added signage indicating not to work on this equipment while energized? The next closest disconnect is in the controller cabinet on the floor below. Depending on location that could be between 50 and 250 feet away (give or take).

 

[jglavin427]

Interesting problem and good photo to illustrate the point. Two thoughts:

1) Locate the motor disconnects in a central location within sight of the motors and provide the 42" of clearance as required. If in sight isn't practical meet 430.102 (B) exception b for industrial locations.

2) The opening paragraph of 110.26 requires all electrical equipment to have access and working space. Also, if you only check for voltage at the motor disconnect you need the full 42". I think proving you won't need to check voltage will be difficult.

Thanks for the reference to 430.102(B) exception. I hadn't seen that before.

 

[jim dungar]

What is the purpose of the disconnect? Is it there as a LOTO point for working on the conveyor or is it to allow work on the motor wiring?

 

[jglavin427]

What is the purpose of the disconnect? Is it there as a LOTO point for working on the conveyor or is it to allow work on the motor wiring?

I would say to work on the motor wiring. There are hundreds of these motors and they need to be able to replace them quickly to keep the system running.

Edit: I should add if they're working on the conveyer, they would shut off the conveyer at the controllers and tag it out there.

 

[jim dungar]

I would say to work on the motor wiring. There are hundreds of these motors and they need to be able to replace them quickly to keep the system running.

Edit: I should add if they're working on the conveyer, they would shut off the conveyer at the controllers and tag it out there.

Your edit makes it sound like they change these motors while the rest of the conveyor is running.

Have they considered going to a 'plug' connected motor?

 

[GoldDigger]

If you conclude that 36" or 42" clearance is required, at least you would only have to widen the catwalk locally for 30" or the total width of the equipment instead of widening the whole catwalk. Assuming that the equipment is not likely to be relocated often or at all.

 

[jglavin427]

Your edit makes it sound like they change these motors while the rest of the conveyor is running.

Have they considered going to a 'plug' connected motor?

Certainly a thought... they are currently working through and replacing with new VFD motors, so a perfect time to change the configuration...

If you conclude that 36" or 42" clearance is required, at least you would only have to widen the catwalk locally for 30" or the total width of the equipment instead of widening the whole catwalk. Assuming that the equipment is not likely to be relocated often or at all.

Not likely to be relocated, no - just.. seems like such a waste of space... :happysad: I guess that's why working clearances are mandatory in the first place though.

 

[tom baker]

Our AHJs in Washington don't require clearance if its a non fused disconnect. A motor may require two disconnects, one in sight from the motor, the other for the controller, only one has to be readily accessible. Mike Holt has a graphic that explains this.

 

[Carultch]

2014 NEC. We had a discussion about working clearances related to disconnects. The language in 110.26(A) "likely to require examination, adjustment, servicing or maintenance while energized" led some of my colleagues to question the existing installation at our facility.

We have a conveyer belt system with catwalks along most of the belts, and each belt drive motor has an associated disconnect next to it mounted on the side where the catwalk is. All drives are 480V 3Ph. If it meets the requirements of 110.26(A) then 42 inches are required in front. Catwalks are only 29 inches wide. My contention was that having the disconnect precludes the motors from meeting that requirement, and the disconnect itself is not likely to require servicing so it too is code compliant as installed.

View attachment 12182

There is a large project coming up to upgrade and extend the conveyers and everyone wants to avoid a disaster in permitting if it turns out the catwalks need to be widened (would be a huge and expensive endeavor).

In a future version of this project, can you build a 30" catwalk, and spin the disconnect such that it has its requisite 42" of clearance along the catwalk length?

 

[Strathead]

This issue has been discussed here many times with very opposing opinions. I disagree with Augie. I contend that the interpretation that requires clearance in front of a disconnect also requires clearance in front of a duplex receptacle, (which is in fact, a disconnect). We put them above ceilings, on platforms, behind equipment etc. The real issue that should be addressed with disconnect is that they are accessible when the equipment the disconnect is in operation. I also disagree with Jim's inspection department regarding fused vs. non-fused disconnects, or at least those that are designed today. As there are no energized parts when they are opened to change fuses.

There was a time when we, as electricians did a lot of stupid things that were acceptable. That time is not now. I won't tolerate my guys plugging in or bolting on a breaker in a hot panel without a class II suit on. It is a fireable first time offense. I used to do it all the time. Go back further I watched "old-timers" (which is now me) check for voltage with the back of their knuckles (so their hand wouldn't close on the bus.) Or carry one screwdriver that was a shorting bar. It was their circuit tracer. Sort the recep, change it and then go flip on the breaker.

My point is that things evolve and we have come to the point where common training and equipment design means that you have to defeat safeties and violate OSHA and company regulations to have a hazard from less clearance in front of a disconnect. In fact, I think you are more likely to encounter a problem with that receptacle.

 

[E16]

In a future version of this project, can you build a 30" catwalk, and spin the disconnect such that it has its requisite 42" of clearance along the catwalk length?

I was thinking what if you could build it off with some strut and run it parallel with the cat walk? Looks like the motor is sticking out a ways so the disconnect would not be a trip hazard.

 

[jglavin427]

Thanks! I appreciate all the input.