Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at firstname.lastname@example.org. Answers are based on the 2020 NEC.
Dedicated spaces for vaccinations
In a series of chain drug stores, we have areas designated as immunization rooms. These spaces are for COVID-19, flu, shingles and other common vaccinations provided by a pharmacist. As these are dedicated spaces for injections by a medical professional, do the requirements of 517.13 apply? Do we need a wiring method that qualifies as an equipment grounding conductor (EGC) along with a separate copper-insulated EGC?
No; see Section 517.10, which explains/requires where Part II of Article 517 does and does not apply. 517.10(B)(3) mandates that areas used exclusively for intramuscular injections (immunizations) are not covered by Part II of Article 517, and 517.13 would not apply. It is important to note that in addition to areas used exclusively for (a) intramuscular injections, (b) psychiatry and psychotherapy, (c) alternative medicine and (d) optometry are not covered by Part II of Article 517, and 517.13 would not apply.
Overhead conductors, pools
Where a permanent swimming pool is installed and existing service drop conductors will be over the pool, does the NEC apply? If so, what can we do?
Yes; see Section 680.9, which requires that all overhead conductors meet the clearance requirements in Table 680.9(A). This includes service drop conductors, overhead service conductors and any open overhead wiring for branch circuits and feeders. While the NEC provides such a requirement, it is well understood that service drop conductors are not part of the premises wiring and are not covered by the NEC . Service drop conductors are installed by the electric utility to the service point. The NEC applies only from the service point downstream. In this situation, it would be prudent to contact the utility to see if the service drop could be relocated. Additional possibilities include shifting the location of the pool, or the installation of overhead service conductors or underground service conductors to route them away from the pool.
SER in commercial drop ceilings
In a strip store that is a one-story building, is Type SE/SER permitted as a feeder above a drop-in style ceiling?
No. Where Type SE cable is installed as a branch circuit or feeder, the requirements of 338.10(B) apply. Section 338.10(B)(4) requires installation in accordance with Part II of Article 334 (NM cable), excluding 334.80. See 334.12 for uses not permitted. 334.12(A)(2) prohibits installation within a dropped or suspended ceiling cavity in other than one-family, two-family and multifamily dwellings.
10/12 AWG copper-clad aluminum
With the price of copper through the roof, we are all looking for alternatives. When researching the cost per 1,000-foot reels of Type NM cable, comparing 14 AWG copper to 12 AWG copper-clad aluminum (CCA), and 12 AWG copper to 10 AWG CCA, there is a significant cost savings. Can we use CCA in dwelling units?
The NEC permits the use of CCA. It is important to check for any existing local codes that may modify the use of smaller sizes of aluminum or CCA wiring. See 240.4(D)(4) and (D)(6), which limit (in general) the application of overcurrent protection for 12 AWG CCA to not exceed 15A and 10 AWG CCA to not exceed 20A. During the last two NEC revision cycles, CCA use has seen significant discussion. Stay tuned in the 2023 NEC .
The NEC now requires a 20A branch circuit for the garage receptacles in dwellings. While this new rule makes sense, it also prohibits me from adding receptacles for the garage door openers and lighting. Do I now need two circuits in the garage? Is that right?
See 210.11(C) for required branch circuits in dwelling units. Section 210.11(C)(4) requires at least one 120V, 20A branch circuit for the receptacle outlets required by 210.52(G)(1) in garages attached and detached with electric power. This requirement prescriptively states that this circuit shall have no other outlets, meaning, for example, lighting outlets and receptacles for garage door openers. There is an exception permitting this branch circuit to supply readily accessible outdoor receptacle outlets.
It is important to understand that this branch-circuit requirement in 210.11(C) is for the required receptacle outlets in each “vehicle bay” in the garage. See 210.52(G)(1), which requires at least one receptacle outlet be installed in each vehicle bay not more than 5½ feet above the floor.
This eliminates the receptacles installed for the garage door openers from this circuit. One of the key points of substantiation for this branch circuit is the use of power tools, such as table saws or air compressors, in a dwelling unit garage.
In the 2014 NEC , 210.52(G)(1) required at least one receptacle outlet for each car space. This requirement prohibited the branch circuit supplying car space receptacles from supplying outlets outside of the garage. The reason for this prohibition was due to the fact that an outdoor receptacle could be exposed to moisture and trip the GFCI device protecting the receptacles for the garage door openers, preventing their operation.
The current requirement is for a 20A branch circuit to supply receptacle outlets in each vehicle bay. These receptacle outlets must be installed not more than 5½ feet high and be readily accessible outdoor receptacle outlets may be supplied by this branch circuit.
Exposed cable in a drop ceiling
Hoping you can settle a job-site debate. Where a cable assembly is installed above a lay-in type 2-by-4 drop ceiling, is it exposed?
Yes, a cable assembly or any other wiring method installed above a lay-in type ceiling with panels that can be removed for access are considered to be exposed. See the Article 100 definition of “exposed (as applied to wiring methods).” Any wiring method run on or attached to the surface or behind panels designed to allow access is, by definition, an exposed wiring method. This means that all requirements for exposed work (e.g., 3XX.15) apply.
One size larger?
At an educational seminar, a city official stated that a service overcurrent device must be larger than any remote downstream device supplied. The same individual failed a single-family home job because we installed a 100A main in a downstream panelboard protected by a 100A service disconnect. We can't find anything in the NEC to support his interpretation. Can you help?
The requirement that is being referenced by the authority having jurisdiction deals with “locked or inaccessible” service overcurrent protective devices (OCPDs). Section 230.92 requires that where a service OCPD is locked, sealed or not readily accessible to the occupant, any branch circuit or feeder OCPDs must be of a lower amp rating than the service equipment. The intent of this rule is an attempt to ensure that the service OCPD does not open on an overload before the downstream feeder or branch-circuit device. This would not apply in the installation you reference. In a single-family dwelling, the occupant would always have ready access to both devices.
It is important to note that the general rule for access to OCPDs is in Section 240.24(B). Each occupant must have ready access to all OCPDs supplying that occupancy. This requirement permits a service OCPD to be inaccessible to the occupant where electric service and electrical maintenance are provided by the building management and are under continuous building management supervision.
Power inlet, optional standby
Where power inlets are installed for temporary connection to a portable generator for optional standby, are signs required? Notes on plan-reviewed drawings have us confused.
Yes; see Section 702.7(C). An optional standby generator can be installed as a separately derived (bonded neutral) or a nonseparately derived (floating neutral) system. Required signage will alert the installer to the proper configuration of the portable standby generator.