View Full Version : UL 508A
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.
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...
September 7th, 2004, 11:51 PM
Is there any other little know facts, oddball stuff, etc.?
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