UL 508A 66.6.1A

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petersonra

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Does UL 508A 66.6.1.A should mean that Disconnect Switch Should physical mounted on top of all other components except Terminals?

66.6.1 A disconnecting means shall be provided for each incoming supply source. Other than terminals,
no components shall be located on the line side of the disconnecting means.

Perhaps you can rephrase your question. I am not sure just what it is you are asking. My copy of the standard does not have a paragraph 66.6.1.A. Just 66.6.1.
 

Jraef

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Perhaps you can rephrase your question. I am not sure just what it is you are asking. My copy of the standard does not have a paragraph 66.6.1.A. Just 66.6.1.

Methinks he is misinterpreting the "A" that begins the sentence with being part of the paragraph number...

New122,
They are not referring to the physical location of the disconnect device, they are referring to the electrical flow. The main disconnect must disconnect all power coming into the panel, with the exception of the line terminals of the disconnect itself. Nobody cares where you decide to locate the switch, but the CONVENTIONAL wisdom is to put it in the upper corner, opposite of the enclosure door hinge. That is the way all Flange Mount Disconnect Enclosures are made, but if you use a rotary through-the-door operated switch, it can go anywhere you like.

Just be careful that the arc of the door swing does not make it so that your interlock mechanism gets interfered with and hang up on you. There are few things more frustrating that discovering, after the fact, that you cannot open the enclosure because the door interlock can't let go. I know...
 

petersonra

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Northern illinois
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engineer
Methinks he is misinterpreting the "A" that begins the sentence with being part of the paragraph number...

New122,
They are not referring to the physical location of the disconnect device, they are referring to the electrical flow. The main disconnect must disconnect all power coming into the panel, with the exception of the line terminals of the disconnect itself. Nobody cares where you decide to locate the switch, but the CONVENTIONAL wisdom is to put it in the upper corner, opposite of the enclosure door hinge. That is the way all Flange Mount Disconnect Enclosures are made, but if you use a rotary through-the-door operated switch, it can go anywhere you like.
I actually think it probably means you cannot locate components physically on the line side of the disconnect. that makes sense to me since you need that space for incoming conductors.

if it meant you could not wire anything to the line side, one would think it would say that. however, you are specially allowed to wire lighting transformers to the line side of a disconnect and the paragraph does not mention any exceptions.

the word "located" certainly implies a physical location.
 

GoldDigger

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But it leaves a whole rat's nest of interpretation on just where the physical line side of the disconnect is in a three dimensional system!
Unless they are talking only about the inside of the disconnect enclosure and not the whole assembly, as the OP seems to be interpreting it.
 

Jraef

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Yes, but look at the context; that section of 508 is all about the power WIRING, not component layout, clearances etc. The issue of not putting anything physically in front of the line terminals would be covered by the wire bending space requirements.
 

petersonra

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Location
Northern illinois
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engineer
But it leaves a whole rat's nest of interpretation on just where the physical line side of the disconnect is in a three dimensional system!
Unless they are talking only about the inside of the disconnect enclosure and not the whole assembly, as the OP seems to be interpreting it.

I think the "line side" is a pretty well defined area. It extends perpendicular to the line terminals away from the disconnect. I think the wording requires it go all the way to the wall of the enclosure.

I think you can make a good argument that the provision would allow the disconnect to be mounted off the panel and the space below the disconnect could have components, although I would not do it as I would not want to have big wires hanging over components.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Yes, but look at the context; that section of 508 is all about the power WIRING, not component layout, clearances etc. The issue of not putting anything physically in front of the line terminals would be covered by the wire bending space requirements.

the bending space does not extend to the enclosure wall.

66.5 is entitled "power wiring". 66.6 is entitled "disconnecting means". each of the individual paragraphs in part 66 covers separate things.

66.1 Enclosures
66.2 Electrical assembly
66.3 Grounding
66.4 Field wiring ? power circuits
66.5 Internal wiring ? power circuits
66.6 Disconnecting means
66.7 Branch circuit protection
66.8 Motor controllers
66.9 Internal wiring of control circuit
66.10 Overcurrent protection of common control circuit
66.11 Operator controls

Incidentally, while not specifically relevant to this discussion parts 65 through 67 are only required if the control panel is for an industrial machine.

INDUSTRIAL MACHINERY
65 General
65.1 These requirements cover industrial control panels for industrial machinery (NFPA 79, Electrical
Standard for Industrial Machinery). The following types of machines are identified as industrial machinery:
 
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