disconnect 2

[dubois]

I have a customer how wants to used a rotary disconnect in the control panel with a (Hoffman) hinged window kit over the handle. I Don't believe this would meet code. The NFPA 79 for machine building reads the disconnect needs to be readily accessible. Can anyone add to this..... Thanks

 

[jraef]

I have to honestly say that that is a new one. Why on earth would they want a rotary disconnect handle, then put it behind a door, clear or otherwise?

Anyway, I believe your assessment of the NFPA 79 rules is correct. The point behind "accessibility" is to facilitate a quick way to turn power off in an emergency. But if they have a separate EPO (Emergency Power Off) or EMO (EMergency Off) system in place that can be activated by, for instance an Emergency Stop push button on the outside which activates a UV Release on a circuit breaker or opens a main power contactor, then it may be legitimate to put the disconnect behind a window I suppose. I still don't see the point.

 

[dubois]

The control panel is for a router that runs at 400HZ. The customer wants to put a safety switch on the door which tie into a safety module in the e-stop circuit. This would cause the motor to brake before it could be serviced. Now this could take up to 10-15 sec. to brake at that time a person could still turn the disconnect off not letting the motor to brake.

The point is I don't like the ideal of putting a door over the disconnect. I'm looking for more arguments on this subject.

 

[LionelHutz]

Well, we've supplied a few units with the breaker handle inside the door on another hinged panel covering everything inside the enclosure. It was for an outdoor application so the operators were on same said panel and I believe there was a window in the door too so the display and lights were visible. We've also supplied large breakers through the door with another door over them to get a Type 12 rating on the enclosure. Not questioned by an inspector yet. As long as the cover is simple to open it should pass. The interpretation of "readily accessible" is very open.

However, might I suggest some wiring and a light that says something like "Safe to Turn Off" or "Do Not Turn Off" or something similar instead. The cover still won't guarantee the operator waits 15 seconds before shutting the thing off.

 

[itsmoked]

Yes and if the intent is to extend the turn-OFF time then that probably won't fly.. A label is your only recourse.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com