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Motor Disconnects, Part 1

Motor Disconnects, Part 1Is the following statement true or false? Every motor must have a disconnect, and that disconnect must be installed within sight of the motor.

The statement may sound right, but technically it’s false. The disconnect for the motor controller can serve as the disconnect for the motor [430.102(A) and (C)]. The logic here is that if the controller has a disconnect, it’s effectively disconnecting the motor anyhow so you don’t need a second disconnect at the motor. But the controller has to be within sight of the motor or you’ll need another disconnect for the motor.

Also, there are two conditions for which a disconnect isn’t required.

  1. Where the location of the disconnect is impracticable or introduces additional increased hazards to persons or property. In fact, the 2014 NEC adds a new Informational Note that gives examples of such locations.
  2. In industrial applications, where conditions of maintenance and supervision ensure that only qualified people service the equipment. But you must have written safety procedures.

So if you don’t have a disconnect, how do you isolate the motor for servicing? You do a lockout/tagout on the branch circuit breaker (or fuses).

That covers the main points of the first one-eighth of Article 430, Part IX. The rest of  Part IX provides requirements for the disconnect itself; many depend upon the application. In our next issue we’ll start with the disconnect operation requirements.

Part 2 » | Source: Mark Lamendola | Mindconnection