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There are many major changes in the 2002 National Electrical Code (NEC), but none will affect more installations than the change involving motor disconnect locations. As more municipalities accept the 2002 NEC, electricians, electrical contractors and electrical maintenance personnel working on residential, commercial and industrial installations may now be required to provide motor disconnects within sight from the motor.
The requirement to have a disconnecting means within sight of the motor controller and within sight of the motor and the driven machinery is a safety issue. The ability to safely work on a motor, a motor controller or any motor-driven machinery starts with being able to turn the power off to the motor and its related equipment. Anyone working on the motor and it circuitry must feel confident that the power will remain off until the work has been completed and the circuit can be safely re-energized.
Section 430.102 provides the requirements for locating the motor disconnecting means and a clear understanding of this information is imperative in understanding the reason for the change. An individual disconnecting means must be installed for each motor controller so power can be disconnected from the controller. This disconnecting means must be located in sight from the motor controller location.
The term “in sight from” is defined in Article 100 as follows: “Where this Code specifies that one equipment shall be “in sight from” another equipment, the specified equipment is to be visible and not more than 15 m (50 ft) distant from the other.”
There are two exceptions to this rule. The first exception is for motor circuits operating at more than 600 volts. The motor controller disconnecting means can be located out of sight from the controller where the disconnecting means is capable of being locked in the open position. Additionally, the controller must be marked with a warning label giving the location of the disconnecting means.
The second exception permits a single disconnecting means for a group of coordinated controllers that drive several parts of a single machine. The disconnecting means must be located within sight of the multiple controllers and in sight from the machinery or apparatus.
Section 430.102(B) requires a disconnecting means to be located in sight from the motor and the driven machinery. If the disconnecting means for the controller is in sight from both the controller and the motor, then no other disconnecting means is required.
In previous editions of the NEC, the disconnecting means for the motor was permitted to be omitted if the disconnecting means for the controller was located within sight of the controller and capable of being locked in the off position. In the 2002 NEC, the exception permits only two conditions where the disconnecting means for the motor can be omitted.
The first is where the location of the disconnecting means in sight from the motor location is impracticable or where it introduces additional or increased hazard. An example of this increased hazard would be a motor rated in excess of 100 horsepower. Having the disconnecting means in proximity to a large horsepower motor could subject the operator to injury during energizing or de-energizing of the motor. Locating a disconnecting means in a hazardous (classified) location would be another example of an “increased hazard.” An increased hazard would be much easier to establish than proving that the disconnecting means location is impracticable.
The second condition is for industrial installations with a written safety procedure for lockout/tagout and where maintenance and supervision ensure that only qualified persons service the equipment. Both NFPA 70E, the Standard for Electrical Safety Requirements for Employee Workplaces and the Occupational Safety and Health Administration (OSHA) require lockout/tagout training for personnel and require qualified personnel to work on electrical equipment. Information on lockout/tagout procedures is available in NFPA 70E and OSHA documents.
If either condition one or two is used, the disconnecting means for the controller must be capable of being individually locked in the open position. The mechanism for the lockout must be permanently installed on or at the switch or circuit breaker being used as the disconnecting means at the controller. A lock on panelboard door would not meet the requirement for an individual lock as required in the exception.
Electrical safety in the home and at work is a requirement for everyone involved in our industry. Safety in a commercial or industrial workplace is also a requirement of the OSHA and is the law. Closely following the new requirements in the 2002 NEC for motor disconnect locations will help make safety a reality. EC
ODE is staff engineering associate at Underwriters Laboratories Inc., in Research Triangle Park, N.C. He can be reached at 919.549.1726 or via e-mail at [email protected].