Touch screen Computer in UL508A cabinet 1

[falconracer]

has anyone used a touchscreen inteface in a panel that has been built to the ul508a standard? ant compliance problems? Any help you'd be good at this time.......

 

[OperaHouse]

Comply with what? UL-508 is just basically a spacing standard. So it probably won't burn up or shock you.

 

[PUMPDESIGNER]

UL 508A has two considerations on this:
1 - Is the device recognized (U with backwards R)
2 - If the touch screen has penetrated the panel, then the touch screen must have a UL penetration rating equal to the enclosure, or the entire enclosure rating must be de-rated to the touch screen rating. In other words, if the panel is a NEMA 4X, then the touchscreen must be rated by UL for NEMA 4X penetration rating, and if no rating then the panel becomes a what, NEMA 1 or something?

If the touchscreen has no UL recognition or listing, then you can still use it if you provide power to the device with certain restrictions. I am not near my 508A book at the moment, but it goes something like this:

Non-UL device must be powered by a power supply double of the required power output (1 amp supply feeding .5 amp load). Also, I think there is a low voltage requirement where you must supply only 30 volts or less to a non-UL device, but I am not sure about that.

If you need more let me know. The offices where I keep that book are closed now and alarmed, tough to get to and I am tired and lazy.

PUMPDESIGNER

 

[jraef]

Since he is so tired, I'll further Pumpdesigner's comments along the thread of Non- UL listed devices. It is 50V or less. If the voltage required is above 50V (i.e. 120V) it must be supplied by a Class 2 isolation transformer (most readilly available Control Power Transformers qualify) AND have a Ground Fault Circuit Interruptor feeding power to it. This could be a GFI circuit breaker, a GFCI recepatacle or a stand alone GFCI protector mudule as sold by most of the major wiring device mfgrs now, i.e. Hubbell or Leviton. In addition, the non-listed device must be in an area of the enclosure that is barriered off from the rest of the listed device areas. In the case of a non-UL listed touch screen, you can put in on the door, use a GFCI module to feed power to it, and put an inner enclosure around the parts on the inside of the door. Pay heed to his comment about the enclosure rating issue however. If the touch screen is unlisted, it cant possibly retain the rating of the box unless it was only supposed to be Type 1.

If the touch screen IS UL listed or recognized, all this was moot except the enclosure issue.

Quando Omni Flunkus Moritati

 

[PUMPDESIGNER]

jraef - Good job. If I get permanently lazy I'll just have our people pay you for consulting.

PUMPDESIGNER