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- Engineer
501.10(B)(1)(3, 4, and 5) specifies that TC-ER, ITC-ER, and PLTC-ER cables installed in Class I, Div. 2 locations "shall include an equipment grounding conductor in addition to a drain wire." Articles 502/503 have the same language for Class II and III. I believe this is a recent addition in the last few editions, at least for ITC-ER and PLTC-ER.
Scenario 1: A piece of equipment is otherwise properly grounded by having its case bonded to grounded structure or connected directly to a ground rod. A -ER cable runs to it. Need this cable contain an EGC? It seems having both would be poor practice because it's likely to create a ground loop.
Scenario 2: A piece of equipment has multiple -ER cables running to it, for example one for power and several for signals. Need every cable have an EGC, or only one? The former would not only create ground loops, but possibly direct fault current into small signal cable conductors. One properly-sized EGC in the power cable would be a better solution.
Nobody I've talked to even knew this requirement existed, including my friendly local AHJ. I assume part of the intent here is "don't connect the drain wire on both ends and call it an EGC," which is well and good, but requiring an EGC on every cable goes way beyond that. I know there are some people on here who are more involved in the NFPA inside baseball, so I'd be curious to know the "why" behind this rule.
Scenario 1: A piece of equipment is otherwise properly grounded by having its case bonded to grounded structure or connected directly to a ground rod. A -ER cable runs to it. Need this cable contain an EGC? It seems having both would be poor practice because it's likely to create a ground loop.
Scenario 2: A piece of equipment has multiple -ER cables running to it, for example one for power and several for signals. Need every cable have an EGC, or only one? The former would not only create ground loops, but possibly direct fault current into small signal cable conductors. One properly-sized EGC in the power cable would be a better solution.
Nobody I've talked to even knew this requirement existed, including my friendly local AHJ. I assume part of the intent here is "don't connect the drain wire on both ends and call it an EGC," which is well and good, but requiring an EGC on every cable goes way beyond that. I know there are some people on here who are more involved in the NFPA inside baseball, so I'd be curious to know the "why" behind this rule.