Class 2 control center 1

[GOTWW]

If multiple (seperately derived) class 2-control wiring enter a single "control panel" what are the code implications? Since the 120V motor controls are derived from independent sources of power, servicing the units can intoduce the potential of electrical shock.. etc/ no clear means of disconnect. Not clear to me per 2002 NEC?

 

[advidana]

It is not clear what you are asking , everything alway applies in the nec it depends on what you want to do.

 

[busbar]

One reference may be NEMA Std ICS 1-2000 Industrial Controls and Systems, General Requirements §7.5, cataloged at

http://www.nema.org

or, possibly others in the ICS 1 series.

 

[skiier]

If you have a motor- OF ANY TYPE!- and there is potential to get hurt from mechanical movement you need an isolating disconnect. And yes damper motors are motors as well - really strong tourqey hurtful little motors if I remeber right. Specifically if the source of power (be it a breaker or fuse or whatever) is over 30'(south of the 49TH) or 9.5m (north of the 49TH) from the motor and that source is not lockable in the "off" position you need a disconnect.
Why argue, common sense tells you it is easier to service whatever it is regardless of the number of sources within the device.

 

[GOTWW]

There is a requirement to control several petrol pumps located inside a Class 1, Div 1, CD area remotely from a non-class area. The motor starters, switched to auto, the class II 120V control leads all enter a common start-stop station. I was curious to the disconnect requirements of these separately derived class 2 voltages when servicing the control panel, not the motors.

 

[jraef]

I believe it is acceptable for you to simply provide adequate labeling indicating the presence of multiple foreign voltage sources if it is not practical to disconnect them all when the door is opened. There are spring-loaded door switches available that will open the circuit when the door is opened, but theat becomes cumbersome in control stations in particular.

When there are only a few, I use these, with the "pull-to-cheat" feature so that I can test circuits with the door open.

http://catalog.sensing.honeywell.co...1,271132,271835,271916,271917&P=316&CURRITM=0

"Venditori de oleum-vipera non vigere excordis populi"

 

[GOTWW]

At least in the current state of emergency breakdown maintenance at our facilities. These switches would last until the next "emergency”, a few cuss words, and be bypassed as the first trouble shooting method. I like labeling the leads. Control technicians should be well versed in the hazards associated with troubleshooting these types of systems, If not, they have no business of opening any panels. (The lawyer’s would disagree however)

a star for trying however,