Nfpa79 E-stop Reset And Restart

[VinceS]

It is clear that the NFPA79 guidelines for restarting equipment after a type 0 or 1 stop event should not restart previously running equipment.
In the case of 2 wire controlled motor starter. The control power was removed during a commanded E-Stop event via the MCR. When the E-Stop is reset and the commanded event ends, the MCR restores control power and all 2 wire controlled equipment will restart, providing all switch positions remain the same.
Now the question: Did the 2 wire controlled device restart due to the E-Stop being reset or due to the position of the start command of the 2 wire device?

 

[pfalcon]

It is clear that the NFPA79 guidelines for restarting equipment after a type 0 or 1 stop event should not restart previously running equipment.

True

In the case of 2 wire controlled motor starter. The control power was removed during a commanded E-Stop event via the MCR. When the E-Stop is reset and the commanded event ends, the MCR restores control power and all 2 wire controlled equipment will restart, providing all switch positions remain the same.

False. A separate action other than resetting the Estop is required before any device restarts. Otherwise you are in violation.

Now the question: Did the 2 wire controlled device restart due to the E-Stop being reset or due to the position of the start command of the 2 wire device?

Both caused the restart of the device. This isn't an either-or scenario. All contributors get credit. An auditor will reset the Estop and then fail you for any device that restarts.

 

[VinceS]

Thanks

Thanks

Thanks, My thoughts were the same. I guess I wasn't clear as to E-stop button reset and E-stop Command reset (commanded event) , sorry for the confusion.

 

[jnsane84]

In all equipment I've worked on just reseting the E-stop should not restart any components, it should only restore control power at which you should have to command all devices to restart. If anything restarts merely from resetting the E-stop then something is definately not right. I concur with you guys.

 

[petersonra]

this requirement is one of the reasons why most companies have stopped putting h-o-a switches on motors that are part of industrial machinery. you would need to add a start and a stop pb on the hand side to comply with this requirement. simpler and cheaper to just eliminate the manual switches altogether.