UL 508A - PLCS.net

93lt1 · September 2nd, 2004, 10:03 AM

I have a few questions regarding the UL508A specification.

I believe this spec. requires a seperation of power and control wiring/devices in a control panel. What is required to comply with the term "seperation"?

The system I am talking about is 208V 3ph. power and 120V control. It is a small panel: 2 motor starters, Micrologix 1000, disconnect etc.

icky812 · September 2nd, 2004, 12:28 PM

For starters you are not allowed to run power wiring and control wiring in the same busway(Panduit) or bundled together.

I always had at least an inch of seperation where wires had to run parallel and never had a problem with my UL inspector.

In my dealings with UL using common sense was typically the right thing to do.

Your mileage may vary...

93lt1 · September 7th, 2004, 11:51 PM

Is there any other little know facts, oddball stuff, etc.?

Bitmore · September 8th, 2004, 12:24 AM

The stipulation is that they must be physically separated. The spec also states that in a wireway there must be some physical device or construction practice that can accomplish this separation. In practice we usually use panduit like 2 2inch panduit (one is stripped of one side) and place them under a 4inch cover. Other physical means are acceptable, for one OEM we separate the Medium Voltage (high voltage doesn't start until greater than 600 volts?)with a grounding mesh of copper braid that is anchored by the panduit mounting screws every 4 inches. But as was started before "results may vary!" Crossing wires has never been an issue with any inspector I know, as long as, the insulation of both conductors is rated for the highest voltage present.

just a bitmore

September 2nd, 2004, 10:03 AM	#1
93lt1 Member Join Date: Apr 2002 Location: Cedar Rapids, Iowa Posts: 993	UL 508A I have a few questions regarding the UL508A specification. I believe this spec. requires a seperation of power and control wiring/devices in a control panel. What is required to comply with the term "seperation"? The system I am talking about is 208V 3ph. power and 120V control. It is a small panel: 2 motor starters, Micrologix 1000, disconnect etc. __________________ SSC Automation Last edited by 93lt1; September 2nd, 2004 at 10:13 AM.

September 7th, 2004, 11:51 PM	#3
93lt1 Member Join Date: Apr 2002 Location: Cedar Rapids, Iowa Posts: 993	Is there any other little know facts, oddball stuff, etc.? __________________ SSC Automation

September 8th, 2004, 12:24 AM	#4
Bitmore Member Join Date: Dec 2003 Location: Automation Alley, Oakland County, Michigan Posts: 477	The stipulation is that they must be physically separated. The spec also states that in a wireway there must be some physical device or construction practice that can accomplish this separation. In practice we usually use panduit like 2 2inch panduit (one is stripped of one side) and place them under a 4inch cover. Other physical means are acceptable, for one OEM we separate the Medium Voltage (high voltage doesn't start until greater than 600 volts?)with a grounding mesh of copper braid that is anchored by the panduit mounting screws every 4 inches. But as was started before "results may vary!" Crossing wires has never been an issue with any inspector I know, as long as, the insulation of both conductors is rated for the highest voltage present. just a bitmore __________________ "A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible. There are no prima donnas in engineering." Freeman Dyson Last edited by Bitmore; September 8th, 2004 at 12:27 AM.

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September 2nd, 2004, 12:28 PM	#2
icky812 Member Join Date: May 2002 Location: Cumming, GA Posts: 582	For starters you are not allowed to run power wiring and control wiring in the same busway(Panduit) or bundled together. I always had at least an inch of seperation where wires had to run parallel and never had a problem with my UL inspector. In my dealings with UL using common sense was typically the right thing to do. Your mileage may vary...

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