Non Fused Disconnects in a Technician Area

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We are setting up a work bench area for our engineers and technicians. We have two Square D disconnects mounted on a wall for AC feeds: 1 480vac 3 phase and 1 240 single phase. They are about 5 feet off of the floor. Can we slide a work bench under them against the wall? Does a 3' clearance apply to these like a typical enclosure clearance? The table would not block access to the disconnects unless someone placed equipment in front of them. I suggested putting a sign or tape on the table top or wall so no one puts equipment on the table in front of them. Our safety officer says this violates code. Can someone provide some insight?
 

augie47

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Welcome to the Forum.
Although often overlooked, IMO it would be a violation of 110.26(A)(3) which requires the clearance to be from floor to a height of 6-1/2 ft.
 

charlie b

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Can we slide a work bench under them against the wall?
Sorry, but no.
Does a 3' clearance apply to these like a typical enclosure clearance?
Yes it does.
The table would not block access to the disconnects unless someone placed equipment in front of them. I suggested putting a sign or tape on the table top or wall so no one puts equipment on the table in front of them.
But it would block access. The clearance rule says that there has to be nothing within the space defined by (1) The width of the equipment or 30 inches, whichever is more, (2) The space from the front face of the panel extending 36 inches (for the 240V disconnect) or 42 inches (for the 480V disconnect), and (3) The space from the floor level to 6'-6" above the floor.
Our safety officer says this violates code.
Your safety officer is right.

 

FREEBALL

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york pa usa
could the main disconnects for the testing bench be moved to an area that would meet the clearance, and then could the circuits be continued to a disconnect above the work bench for only ease of operation while testing equipment probably some labeling stating where the disconnect feeding the bench is located but seems there has to be some exception here I cant find one but seems if the main disconnect for both voltages are fed from an area within site that any additional disconnects for testing should be acceptable.
 

FREEBALL

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york pa usa
I understand about the working clearances, but if under supervised control these disconnects could be serviced by personell that understand what needs to be done to perform maintenance safely and since these disconnects are not considered the main emergency shut off, then it should not be an issue because you already have the main disconnects for the workbenches located in the immediate area with the proper clearance. How do testing laboratorys do it I guess is what Im asking. I have seen QA benches where they have multiple disconnects mounted above the bench. It just seems there must be a clause somewhere.
 

petersonra

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I understand about the working clearances, but if under supervised control these disconnects could be serviced by personell that understand what needs to be done to perform maintenance safely and since these disconnects are not considered the main emergency shut off, then it should not be an issue because you already have the main disconnects for the workbenches located in the immediate area with the proper clearance. How do testing laboratorys do it I guess is what Im asking. I have seen QA benches where they have multiple disconnects mounted above the bench. It just seems there must be a clause somewhere.

I agree it is a common thing to see. That does not mean that it meets code. The OP asks about the code issue.
 

charlie b

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It is not about emergency shutoff. That is not the function of any disconnect. Their function is to turn something off, and keep it off, while regularly planned maintenance is conducted. But what about maintenance on the disconnect itself? You can say that they simply need to turn off power upstream of the disconnect. But if the intended maintenance includes thermographic analysis, you need to do that with the disconnect energized and with its cover removed. And if the maintenance technician needs to lean over the desk, in order to remove the cover, he would be in an awkward physical position and there would be an increased risk of slipping.

This is not published anywhere, and is not official, but my belief is that a key reason for maintaining working space clear of all interferences is this: so that if the worker contacts live parts and gets shocked, and if the shock is severe enough to cause his hands to contract so tightly that he is not able to let go, then perhaps the only thing that could save his life is when his muscles lose all control and the weight of his falling body pulls his hand away from the panel. The owner of this forum, Mike Holt, tells a story of personal experience that is something along these lines. He says that if he had not fallen, he would have died that day. But consider this: if there is a desk surface underneath the disconnect, and if the worker is leaning over that surface to get to the disconnect, and if the worker does get a shock, his body will not have the freedom of motion that would cause him to fall onto the floor. Just think in terms of that desk taking away the workers one chance, however small that chance might be, but his one and only chance of surviving the shock.
 

FREEBALL

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york pa usa
Like I said I understand the clearance issue. So say these disconnects are not square D disconnects, simple 20 amp switches, 120 and 277 volts they cannot be mounted above a workbench, what Im trying to say is these switches do not serve any purpose but to disconnect power for testing ? any thermo testing would be performed at the main disconnect. And if the disconnect isn't to be accessible for emergency purposes, then why does the insight rule apply for them, again just asking.
 

charlie b

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And if the disconnect isn't to be accessible for emergency purposes, then why does the insight rule apply for them, again just asking.
It applies so that a person working on the equipment can actually see the disconnect, and thereby be confident that nobody is trying to close it.

I am not saying that if I saw a person getting shocked or a machine trying to destroy itself I would not think about using the disconnect as the method of terminating the event. I am just saying that that is not the disconnect's purpose in life, and as designers we are not obliged to make allowances for it to be used in that way.

 

charlie b

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So say these disconnects are not square D disconnects, simple 20 amp switches, 120 and 277 volts they cannot be mounted above a workbench, what Im trying to say is these switches do not serve any purpose but to disconnect power for testing
A snap switch does not have the requirement for working clearance. A Square D (or other brand) disconnect (with or without fuses) does require working clearance. And the purpose of the switch is not just to disconnect power for testing. It is also to allow wires to be connected so that power can be brought to a component for testing. The connection and disconnection of such wires should not be done energized. But you can't tell me that, regardless of training, qualifications, and procedures, some schmuck working late and anxious to get home is not going to try to save time and cut corners by not walking over to the "other" disconnect location to turn off power first. We can't say that he violated the rules and so deserved what he got. Rather, I say he deserves more from us, the designers and installers and inspectors, and so does his family.

 

Frank DuVal

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So what is the difference in a snap switch (typical light switch) and one with a handle that is larger, i.e. a "safety switch"?

Is it just the fact that a typical safety switch has a cover that does not require a screwdriver to open like a cover on a light switch?

Both can be capable of switching 20 amps and 250 volts.

No one will argue that a wall switch can not be placed above a workbench to turn the bench receptacles on/off, will they?:?

Frank DuVal
 

don_resqcapt19

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A snap switch does not have the requirement for working clearance. ...
The rule requires working clearance from all electrical equipment.
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.
How is a snap switch not equipment?
This code section has needed work for many code cycles, but the code making panel has refused to accept reasonable changes in the section to limit the types of equipment that the rule applies to.
 

don_resqcapt19

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...No one will argue that a wall switch can not be placed above a workbench to turn the bench receptacles on/off, will they?:? ...

Frank DuVal
I will and have as that is exactly what the code rule says. I have also argued that the code required kitchen counter top receptacles are also in violation of the work space rules as found in 110.26.
 

jim dungar

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Wouldn't a strict interpretation of 110.26, also likely preclude locating anything underneath busduct disconnects as well as wall mounted equipment?

About the only relief I see is if there are safeguards (e.g. a safe work practices program or key interlocks) that would preclude the disconnect door from being opened while its line side terminals are energized.
 

Frank DuVal

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Don, that was going to be what I pointed out next. One section requires devices over counters, and another section restricts them.

And if I couldn't put the disposer switch over a counter... then I would hide it inside the cabinet, again, no working clearance, just like the receptacle I plug the disposer and dishwasher into. And then there are stove receptacles...

I say a non fuseable disconnect is just like a snap switch. No need to go into it to work unless it is broken, just like all the no working clearance devices we install everyday. Of course, since it is a "large" object I'm sure every inspector will object. Like when a customer wanted me to hide the A/C disconnect behind the units outdoors. Nope, didn't fly. I will add that in this case, since A/C outdoor units do go bad and get replaced, going into these disconnects is almost a sure thing after it is installed.

So, whatever the AHJ says goes. Unless you have a PE and can give a good argument!

Frank DuVal
 

don_resqcapt19

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Frank,
My problem is that 110.25(A) does not really say what it means.

There are a number of ways that you can read it. Those range from "no equipment requires work space", be cause nothing "requires" energized work. Yes trouble shooting is more difficult with the power off, but it can be done. The other end of the range is that "all equipment is likely to be worked on while energized" and therefore all equipment (as defined in Article 100) requires the 110.26(A) work space.

The section needs work, but there have been a number of proposals to make the needed changes that have all been rejected by the CMP.
 

Aleman

Senior Member
Location
Southern Ca, USA
I would say that because this is only a disconnect, there will be no reason to work in the disconnect enclosure. Like an outlet on a wall or a
snap switch. No fuses to check, no distribution, no breakers. The real hazard will be where the tech is hooking up power to the device he or
she is testing. I would have no problem with setting up a test bench as described. The code may or may not disagree. More importantly
the OP's safety guy does not agree so the OP will now need to find a less practical method of setting up a bench.
 
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