480 Volt Switchgear Clearance

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al

al

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What is the rear clearance required for 480 volt drawout switchgear with only the cable connections in the rear. It would have 22" hinged doors in the back.
 
If you can open the door and see live parts, that creates a possibility, which will be interpreted as "likelihood," that someone may have to do some work in that space. That means that the normal rules for working clearance apply. Assuming this is a Condition 2 situation, you would need 42 inches.
 
charlie b said:
If you can open the door and see live parts, that creates a possibility, which will be interpreted as "likelihood," that someone may have to do some work in that space. That means that the normal rules for working clearance apply. Assuming this is a Condition 2 situation, you would need 42 inches.
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What if it is fully insulated, eg. the cable connections are 'booted'?
 
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charlie b said:
If you can open the door and see live parts, that creates a possibility, which will be interpreted as "likelihood," that someone may have to do some work in that space. That means that the normal rules for working clearance apply. Assuming this is a Condition 2 situation, you would need 42 inches.
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So if the covers were bolted on would it make a difference?
 
al said:
So if the covers were bolted on would it make a difference?
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Nope. What matters is whether the equipment is likely to require work while energized. If there are no live parts accessible from the rear, and specifically if the manufacturer declares that the equipment requires no rear access, you can mount it tight to the wall.
 
Devil's Advocate

Devil's Advocate

charlie b said:
Nope. What matters is whether the equipment is likely to require work while energized. If there are no live parts accessible from the rear, and specifically if the manufacturer declares that the equipment requires no rear access, you can mount it tight to the wall.
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Playing the devil"s advocate, what if I am not going to work on it when it is energized, this is part of my 70E electrical safety plan. Then why would I need the 3'-6"?
 
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al said:
. . . what if I am not going to work on it when it is energized. . . .
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Not relevant. It is not about any one person's plans or intentions. You could leave the company, and a new boss could be brought in, and the work philosophy might be different. I think that many an AHJ will interpret the phrase "likely to require (live work)" as meaning "if it is not physically impossible, then it is likely to happen someday under some set of circumstances."
 
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charlie b said:
Nope. What matters is whether the equipment is likely to require work while energized. .
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Being more of a devil's advocate, by the same logic any 120 vac switch, receptacle, JB, or other equipment with a removable cover would require 30" wide and 36" deep working space since it is electrical equipment.
 
charlie b said:
Not relevant. It is not about any one person's plans or intentions. You could leave the company, and a new boss could be brought in, and the work philosophy might be different. I think that many an AHJ will interpret the phrase "likely to require (live work)" as meaning "if it is not physically impossible, then it is likely to happen someday under some set of circumstances."
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Aren't you contradicting with this statement your previous response to the rear access when it is completely insulated, eg. no live, exposed parts are present when the door or rear access is opened?
 
weressl said:
Aren't you contradicting . . . your previous response. . . ?
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I don't think so. If there are no live parts accessible behind a door, then 110.26 cannot apply, since it is talking about the likelihood of requiring live work. On the other hand, if there are live parts accessible behind a door, then 110.26 does apply, regardless of what any person (or any company policy) says today about never doing live work. The working space must still be reserved.
 
al said:
Being more of a devil's advocate, by the same logic any 120 vac switch, receptacle, JB, or other equipment with a removable cover would require 30" wide and 36" deep working space since it is electrical equipment.
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I would argue that no switch, receptacle, or junction box would ever require live work. As to "other equipment with a removable cover," I suppose it would depend on what the equipment is, and what is behind the cover. For example, I provide working clearance for enclosed circuit breakers and for motor controllers (including VFDs).
 
charlie b said:
I would argue that no switch, receptacle, or junction box would ever require live work.
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Interesting discussion. By the same token, why would switchgear with only cables and lugs (say for example crimped lugs) require live work any more than a switch, receptacle or JB?
 
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