Locating Motor Disconnecting Means

"430-86 [1987 National Electrical Code (NEC)] Motor Not in Sight from Controller. Where a motor and the driven machinery are not in sight from the controller location, the installation shall comply with one of the following conditions: (a) Capable of Being Locked in the Open Position. The controller disconnecting means shall be capable of being locked in the open position. (b) Within Sight from the Motor Location. A manually operable switch that will disconnect the motor from its source of supply shall be placed within sight from the motor location." For many years, the NEC contained the section above regarding placement of controller disconnecting means. During the 1987 Code cycle, Code Making Panel (CMP) 11 took action to delete this section and revise Section 430-102, which provides direction to the placement of motor and controller disconnecting means. CMP 11 split down the middle with eight affirmative votes and eight negative votes. The main objective was to enhance worker safety and more closely unite the motor and controller disconnecting provisions, which were split between Part G, Motor Controllers, and Part H, Disconnecting Means. The comments expressed in the negative votes can be summarized into four major categories as follows: infeasible to locate a disconnecting means within sight of every motor; too costly to provide all of the required disconnecting means; 3) disconnecting means may be required to be located in a hazardous (classified) area; and locating a disconnecting means within sight of the motor may create an additional hazard. During the comment stage, CMP 11 addressed these negative votes and other comments submitted by the public. The result is essentially Section 430-102 as it appears in the 1999 NEC, along with some minor revisions and clarifications in the subsequent Code cycles. Section 430-102 (b) in the 1987 NEC read: (b) Motor. A disconnecting means shall be located in sight from the motor location and the driven machinery location. Exception: Where the disconnecting means provided in accordance with Section 430-102(a) is capable of being locked in the open position. Surprisingly, the inclusion of this exception satisfied all of the issues raised by the negative voters. CMP 11 accepted the deletion of Section 430-86 and the revision to 430-102 unanimously. Analysis A comparison of the present requirements and the provisions of Section 430-86 reveals that in addition to merely restating the requirement in a positive manner, the option of installing a manually operable switch in sight of the motor location was removed. Granted this was only an option, but it did reinforce the notion that the disconnecting means should be placed within sight of the motor location. Unfortunately, since this exception was included in the 1987 NEC, it has been widely used in industry to exclude the placement of a disconnecting means in sight of the motor location. The general rule is, and ought to remain, that a disconnecting means be placed in sight of the motor location or the driven machinery location. The exception should only be utilized for special applications. For example, a motor disconnecting means should not be required to be located within sight of the motor location if the placement of the disconnecting means would be in a hazardous (classified) location. Similarly, if the motor was larger than 100 hp, or an adequate load break disconnecting means was not available, the disconnecting means should be permitted to be located in another location. The problem with Section 430-102 is that the general rule (Disconnecting means located within sight of the motor location) is too often merely disregarded and the exception automatically is used in its place. In the vast majority of electrical equipment installations, safety will be enhanced by the placement of the disconnecting means within sight of the motor location. Clearly, the closer the disconnecting means is to the point at which the personnel are working on the equipment, the less the risk of inadvertent unexpected reenergization of the equipment. Only in specialized cases should the exception be applied, and only where it improves the overall safety of the installation. 2002 Proposal Interestingly, CMP 11 revisited this issue in the 2002 Code cycle. Many of the same issues of the negative votes were raised again, but some panel members agree that the use of the exception, in lieu of the general rule, has increasingly been accepted as a valid installation practice, and a general tightening of the requirement may be in order. CMP 11 has accepted in principal a proposal to accomplish this by revising the exception and adding a fine print note (FPN). The proposed exception and FPN will read as follows: "The disconnecting means shall not be required to be in sight of the motor if such a location of the disconnecting means is impracticable or introduces additional or increased hazards to persons or property, and the disconnecting means is individually capable of being locked in the open position. The provision for locking or adding a lock to the disconnecting means shall be permanently installed on or at the switch or circuit breaker used as the disconnecting means. FPN: Some examples of increased or additional hazards include, but are not limited to; motors rated in excess of 100 hp, multi-motor equipment, submersible motors, motors associated with variable frequency drives and motors located in hazardous (classified) locations." This proposed revision is intended to tighten the use of the exception and clarify that in most cases, the safest installation is to locate the motor disconnecting means within sight of the motor location. The exception is not without problems. The standard for when the exception is appropriate is "impracticality," which can be difficult to define. However, good electrical design practice incorporates pre-job consultation with the authority having jurisdiction to see if the installation is acceptable as designed. If the location of the disconnecting means proves to be infeasible, or would increase the potential hazard to personnel, the disconnecting means can be located out of sight of the motor location. The FPN provides some help in determining when it is infeasible or would create a greater hazard to locate the disconnecting means in sight from the motor location. These standards, "infeasibility" and "greater hazard" are already used through the Occupational Safety & Health Administration (OSHA) Regulations and have proven to be workable and enforceable. Even the use of the "impracticality" standard is already in use in the Code. See for example, 230-54 Exception. Often the term can be used in a manner which is arguably vague and unenforceable. But it also can be a good standard for applications where discretion and latitude are necessary. In this usage, the term provides the designer and installer sufficient latitude and avoids the use of an exhaustive "laundry list," which might otherwise be needed to list all of the possible exceptions to the general rule. Summary CMP 11 has provided a good foundation for the re-opening of a long-running debate on the location and placement of motor and controller disconnecting means. Clearly, the section needs revision. There are problems in the field with the application of this provision. Over the past few Code cycles, several revisions have already been made to clarify the intent of the requirement and the exception. In addition, OSHA accident and injury data document that far too many accidents occur each year from the unexpected reenergization or start-up of equipment. The proposed revision accepted by CMP 11 is the starting point for a workable exception to this important Code provision. One that recognizes the need for latitude in the placement of the motor disconnecting means, while still ensuring workers adequate protection from inadvertent reenergization of electrical equipment. CALLANAN is director of Safety, Codes, & Standards at the National Joint Apprenticeship & Training Committee. He can be reached at mic3@concentric.net.

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