Jim Dollard has an extensive background in codes and standards. If you have a query about the National Electrical Code (NEC), Jim will help you solve it. Questions can be sent to firstname.lastname@example.org. Answers are based on the 2017 NEC.
Auxiliary grounding electrodes
Are grounding electrodes required for all parking lot light poles? The engineered drawings showed a ground rod at each light pole located 6 feet from the sonotube with a 6 AWG copper conductor cad-welded to the rebar supporting the bolt pattern. During our electrical inspection we were told the 6 AWG was installed incorrectly and that it needed to be attached to the metal light pole where the inspector could see it. There was a factory-installed lug for the equipment grounding conductor (EGC) in the pole base and the inspector wanted the termination there. Fortunately, the foreman had pictures of several pole bases that showed the grounding installation before the concrete was poured and the situation was resolved with the inspector telling us not to do it in that manner again. Can you offer some insight on this installation?
Grounding electrodes are not required for outdoor pole-mounted fixtures. Section 250.54 permits an auxiliary grounding electrode to be installed and connected to the EGC. This is a permissive requirement and goes above the minimum installation requirements. Section 410.46 requires luminaires with exposed metal parts to be provided with a means to connect the EGC. By bonding the 6 AWG conductor to the ground rod and the bolt pattern, you achieved the connection to the EGC in the manner designed for this project. It is extremely important to get pictures of installations as they are being intalled if they will be inaccessible for inspection. Keep taking those pictures!
Type NM cable above a drop ceiling
When we do retail work in strip malls, we use Type NM cable as our wiring method. Type NM cable is not permitted above lay-in type ceilings, so we use metal clad (MC) cable in those areas for lighting and other branch circuits. If vertical walls above a lay-in type ceiling are insulated, can we install Type NM cable there behind fiberglass insulation without drywall? It would not be exposed. Doesn’t the NEC permit it as long as the insulation has a 15-minute fire rating?
Type NM cable is not permitted to be installed as described in your question. Section 334.12 lists “uses not permitted” for Type NM cable, and list item (2) specifically addresses this question. It is not permitted to install exposed Type NM cable above a lay-in ceiling in other than single- or two-family dwellings. The defined term “exposed” as applied to wiring methods is “on or attached to the surface or behind panels designed to allow access.” Since the cable would be behind panels designed to allow access, and behind only insulation, not a wall finish, it is accessible and exposed.
Section 334.10(3) grants permission to install Type NM cable in structures of Types III, IV and V construction, provided the cable is concealed within a wall that has at least a 15-minute finish rating as identified in listings of fire-rated assemblies. Type NM cable installed behind fiberglass insulation is not concealed. The definition of concealed is “rendered inaccessible by the structure or finish of the building.”
While reviewing the definitions in Section 517.2, I noticed numbers in brackets following many of the defined terms. What do those numbers mean?
The numbers in brackets contain section references to another NFPA document and are informational only [see Section 90.5(C)]. We call this “extract material” because the purview over that text falls under the scope of another NFPA code or standard and is simply extracted into the NEC. In Section 517.2, all of the section references are to NFPA 99, the Health Care Facilities Code.
For example, the definition of “health care facilities” is followed by the section reference in NFPA 99 as follows: [99:3.3.67]. This information allows the user to cross-reference NEC requirements extracted from another code or standard. This is extremely important information for people who may wish to submit public inputs to extracted NEC requirements. In this case, if you wish to revise the definition of healthcare facilities, the public input must be sent to the NFPA 99 committee referencing Section 99:3.3.67 and not Section 517.2 in the NEC.
Abandoned fire alarm cable
Who is responsible for removing old fire alarm cable that has been replaced when a new system is installed? As I read it, there is no reference as to when or who is responsible.
The NEC does not assign jurisdiction to any activity that must be performed to meet a given requirement. The NEC is an installation code that works together with qualified installers, product standards and electrical inspections. Where fire alarm cable is replaced, the old cable is considered to be abandoned and is subject to the requirements of Section 760.25. All accessible portions of abandoned cable must be removed. Where cables are identified for future use, they may be permitted to remain provided they are identified for future use with a tag. The electrical inspector may fail the installation where abandoned cable is not removed. It is extremely important for contractors doing this type of work to include removal in their bid or provide a price to remove the cable because it is likely that the contractor installing the new system and cable will be held responsible for the removal of abandoned fire alarm cable.
Field-applied markings, signs and labels
Can I make my own field-applied labels to cover multiple NEC requirements? We are making a label that will contain the required ungrounded color code and feeder location for panelboards. We will also display our company name, logo and contact information. We use separate labels we purchase by the roll for arc flash hazard warnings.
Yes, you can make your own labels, provided you meet all individual NEC requirements. Section 210.5(C)(1)(b) requires posting of how the ungrounded conductors in a given installation are identified. Section 210.5(C)(1) requires identification where more than one nominal voltage exists, such as installations with both 208/120 and 480/277-volt systems. The label must be permanent, which means it cannot be on a removable panelboard schedule. It must not be handwritten and must be of sufficient durability for the environment. I suggest the label also include your identification of the grounded conductor. This identification is only required where grounded conductors of different systems [200.6(D)] are mixed.
The requirement to mark the supply source when a feeder is involved applies to panelboards, switchboards and switchgear, per Section 408.4(B). This requirement also mandates labels be permanently affixed, not handwritten and durable.
It is important to note that the requirements of Section 110.21(B) apply if you make your own field-applied hazard markings. This includes, but is not limited to, markings required by sections 110.16 and 700.7(B). Section 110.21(B) requires permanent, durable markings that use effective words, colors and symbols. The informational note that accompanies this requirement references an ANSI standard that provides the Code user with information on the use of font sizes, words, colors and symbols.
Overhead busway disconnects
Where busway is installed overhead to supply packaging equipment, is it required to have a chain loop hanging from each disconnect mounted on the busway to allow operation from the floor? The installation I am referring to included new busway with 200-ampere circuit breakers in busway switches to supply the main disconnect for each of 12 packaging machines. We had considered installing chain, but it would have been hanging where the equipment operators stand to work. Our concern was that they would remove or tie up the chain. We provided two hook sticks that are evenly spaced among the machines next to columns to allow for opening or closing the disconnecting means from the floor. The inspector is requiring each disconnect to have chain installed. Is that required?
Section 368.17(C) addresses accessibility of the plug-in devices above the equipment. Where the disconnecting means is mounted out of reach, a suitable means, such as ropes, chains or sticks, must be provided for operating the disconnecting means from the floor. There is no prescriptive text that prohibits a single stick from being supplied to operate one or more disconnects. If the machines are in proximity to one another, there is no reason that a single hook stick could not be used for one or more disconnects. In my opinion, you have met the intent of this requirement, and individual chains would not be required.
A new Exception No. 4 has been added to Section 368.17(C) in the 2017 NEC. It provides valuable insight to the requirement’s intent in the 2014 NEC. This new exception exempts the need for a chain, rope or stick where the conductors supplied by the busway disconnect supply a readily accessible disconnect. The installation you have described would fall under this exception, and the need for chain or a stick no longer applies if your jurisdiction has already adapted the 2017 NEC.