The phrase "functionally associated" is used in the Code 4 times, but is not defined (see NEC 620.3(A), 725.26(B)1), 725.26(B)(4) and 770.133(A)). This phrase has a long history; I understand it goes back to the 1978 NEC as a replacement for prior wording that first entered the NEC in about 1951. In my opinion, it is an inherently ambiguous phrase, and may require the AHJ to intervene and interpret. As a result, the phrase is unenforceable, or at best, a potential source for conflict. Bad Code. In a large industrial complex, can't it be argued that most or all of the cabling is "functionally associated"?
I believe the phrase "functionally associated" in 620.3(A) can be safely interpreted to mean associated with power conversion equipment. In this case, the intended meaning is in the context of its use. Its use in 770.133(A) is somewhat confined to conductors within the same cabinet, outlet box, panel, or similar equipment, which also tends to control the boundaries of "functionally associated".
My question is primarily in regard to the use of "functionally associated" in NEC 725.26(B)(4). Here, the scope of this phrase is NOT controlled by the context of its use. In this broad use, ?functionally associated? can mean different things to different people. Here is a typical example of a situation we may encounter in my specific line of work:
A manufactured skid with multiple mechanical equipment items is supplied as a complete assembly. The skid might include 1 main motor, 2 auxiliary motors (such as lube oil pumps), and a lube oil heater (all 480V). All power cables and Class 1 Remote Control and Signaling signals are in separate 600V type TC cables routed to a remote MCC via a common cable tray. This cable tray is also used to carry the power and control conductors of other nearby equipment (per NEC Chapter 3). Assume for this example that all cables are type TC (not metal-enclosed).
Regarding the above example, here are my questions.
(1) Are the power supply and Class 1 control conductors for the equipment contained within the manufactured skid all ?functionally associated?? I assume so.
(2) What about the conductors of other nearby equipment? This will likely be unassociated, right?
(3) What if that other nearby equipment was in a common service, such as a ?B? compressor?
In the above example, if any of the cables are determined to be unassociated, then 725.26(B)(4) will require a solid fixed barrier separating the Class 1 control conductors from the power supply conductors. What benefit is served? How is this safer? Worst case scenario is where the design is based on a conservative interpretation, but the AHJ, client and/or the inspector don't agree after the installation has been completed.
I plan to submit a proposal to delete 725.26(B)(4), on the grounds that ?functionally associated? is not defined, and is therefore unenforceable. Additionally, the current language unnecessarily restricts the use of combined power and control cable (composite cable), which is a common practice in our industry (industrial applications), and one that can save a significant installation time and material costs.
What are the risks to personnel or equipment if 725.26(B)(4) were to be deleted?
I believe the phrase "functionally associated" in 620.3(A) can be safely interpreted to mean associated with power conversion equipment. In this case, the intended meaning is in the context of its use. Its use in 770.133(A) is somewhat confined to conductors within the same cabinet, outlet box, panel, or similar equipment, which also tends to control the boundaries of "functionally associated".
My question is primarily in regard to the use of "functionally associated" in NEC 725.26(B)(4). Here, the scope of this phrase is NOT controlled by the context of its use. In this broad use, ?functionally associated? can mean different things to different people. Here is a typical example of a situation we may encounter in my specific line of work:
A manufactured skid with multiple mechanical equipment items is supplied as a complete assembly. The skid might include 1 main motor, 2 auxiliary motors (such as lube oil pumps), and a lube oil heater (all 480V). All power cables and Class 1 Remote Control and Signaling signals are in separate 600V type TC cables routed to a remote MCC via a common cable tray. This cable tray is also used to carry the power and control conductors of other nearby equipment (per NEC Chapter 3). Assume for this example that all cables are type TC (not metal-enclosed).
Regarding the above example, here are my questions.
(1) Are the power supply and Class 1 control conductors for the equipment contained within the manufactured skid all ?functionally associated?? I assume so.
(2) What about the conductors of other nearby equipment? This will likely be unassociated, right?
(3) What if that other nearby equipment was in a common service, such as a ?B? compressor?
In the above example, if any of the cables are determined to be unassociated, then 725.26(B)(4) will require a solid fixed barrier separating the Class 1 control conductors from the power supply conductors. What benefit is served? How is this safer? Worst case scenario is where the design is based on a conservative interpretation, but the AHJ, client and/or the inspector don't agree after the installation has been completed.
I plan to submit a proposal to delete 725.26(B)(4), on the grounds that ?functionally associated? is not defined, and is therefore unenforceable. Additionally, the current language unnecessarily restricts the use of combined power and control cable (composite cable), which is a common practice in our industry (industrial applications), and one that can save a significant installation time and material costs.
What are the risks to personnel or equipment if 725.26(B)(4) were to be deleted?
