Russ_H
New member
- Location
- Centreville, AL USA
We are working with a customer whose manufacturing operation includes various machine tools used for final finish on products. As product lines change the process is re-arranged and machines relocated within the work area. Equipment is served by overhead plug in busway (Art 368). The last several re-locations have been done “in house” and machines are fed with SO cable “drops” from the busway plug-in devices. Due to physical arrangement, not all machines are directly under the busway, cord runs can be in the range of 25-75 feet from the nearest busway. Typically cord is simply draped thru the overhead trusses and excess rolled up and tied off. Plant maintenance and safety departments would like to do the next relocation in conformance with NEC requirements. We have been tasked with developing and implementing a model plan.
Article 368.56(B) appears to grant permission for use of Cords and Cable assemblies to service equipment of this type. The requirements appear to be rather straightforward until it gets to exception (B)(2) which allows for cable runs longer than 1.8m(6 ft), under stated conditions. For these longer spans the requirement is that the cable be “supported at intervals not exceeding 2.5 m (8 ft). Our question is, what method is suitable for support of these permitted cables? Can the cables be supported as short span (2.5 m) festoons between short lengths of framing strut, attached to building structure? Can it be supported in continuous runs of chanel raceway or strut? Would cable tray be considered a suitable means of support? (We realize that flexible cords are not in the 392.10(A) list of approved wiring methods in tray, but flexible cord is not a “wiring method” but rather Chapter 4 “Equipment for General Use”.)
There seems to be some “gray” area here that leaves a great deal of latitude in materials and methods available for “support”. Our preferred solution would be to use cable tray along the busway with branches thru the production area, that would allow for good support and ease of eventual relocations. From the tray, we would “roll out” to an overhead “tension take up support device” directly above the equipment served. It appears that this would meet the requirements.
Article 368.56(B) appears to grant permission for use of Cords and Cable assemblies to service equipment of this type. The requirements appear to be rather straightforward until it gets to exception (B)(2) which allows for cable runs longer than 1.8m(6 ft), under stated conditions. For these longer spans the requirement is that the cable be “supported at intervals not exceeding 2.5 m (8 ft). Our question is, what method is suitable for support of these permitted cables? Can the cables be supported as short span (2.5 m) festoons between short lengths of framing strut, attached to building structure? Can it be supported in continuous runs of chanel raceway or strut? Would cable tray be considered a suitable means of support? (We realize that flexible cords are not in the 392.10(A) list of approved wiring methods in tray, but flexible cord is not a “wiring method” but rather Chapter 4 “Equipment for General Use”.)
There seems to be some “gray” area here that leaves a great deal of latitude in materials and methods available for “support”. Our preferred solution would be to use cable tray along the busway with branches thru the production area, that would allow for good support and ease of eventual relocations. From the tray, we would “roll out” to an overhead “tension take up support device” directly above the equipment served. It appears that this would meet the requirements.