I have reveiwed the NEC 409 and nowhere can I find if it is okay to have a external disconnect switch that doesn't "kill" all live parts inside the panel:-? My customer wants to keep the HMI and PLC alive after throwing the main disconnect and I didn't think was an acceptable wiring method ( using no yellow wires either). The switch to kill the HMI and PLC are both internal to the panel....no label either. They actually have panels inside their facility wired this way.....please advise:-?
Safety- Control Panel Disconnecting means
- Thread starter kennipoo
- Start date
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Buck Parrish
Senior Member
- Location
- NC & IN
Your allowed to use the panel as a race way. Therefore if you shut the main off. You can still have live wires in it. I know it sounds screwy but legal. As long as you have the space in the panel
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I believe you need to have a warning label on the outside of the enclosure stating that there is more than one voltage spource and/or that they may not be de-energized when the main disconnect is opened. People like Brady have standards warning labels like this available.
Brady 88320
Brady 60180
Brady 88320
Brady 60180
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Unless there is something new in 2008, this is all article 409 says about control panel disconnecting means.
I don't believe anything in the referenced section of article 430 requires a disconencting emans for a PLC or an HMI.
I don't believe anything in the referenced section of article 430 requires a disconencting emans for a PLC or an HMI.
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