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. Send questions to email@example.com. Answers are based on the 2017 NEC.
Switches for stairways
Where lighting outlets are installed for dwelling unit stairs, is there ever a need to provide a switch on the midpoint landing? Is a switch required in a split-level home where there are only five steps?
Section 210.70(A)(1) requires at least one wall-switch-controlled lighting outlet for stairways in dwelling units. Section 210.70(A)(3) requires that this lighting outlet be controlled by a wall switch at each floor level and landing level that includes an entryway where the stairway between floor levels has six risers or more. There is no requirement to provide a switch on a landing level unless you can enter and exit at that point. If there are five steps, then there are six risers, requiring a switch at each floor level.
I installed a single-branch circuit for elevator pit lights and receptacles as required by the engineered drawings. This branch-circuit-supplied lighting and receptacles in two completely separate elevator pits. The inspector is requiring separate branch circuits for the lighting and the receptacles. This was not on the drawings. Are we responsible for the additional cost, etc.? Why are two circuits necessary?
Requirements for elevator hoistway pit lighting and receptacles are located in Section 620.24. Separate branch circuits are required for the pit lighting and the receptacles. At least one duplex receptacle must be provided in each elevator pit. The elevator pit lighting is not permitted to be GFCI-protected. The reason for two branch circuits is safety-driven. While working in an elevator pit using portable tools, it is possible to trip the upstream overcurrent protective device. Without a separate branch circuit for the lighting, this would leave a person in the dark and would create concerns for their ability to exit safely. This section also requires that a switch for the lighting be readily accessible from the pit access door. I cannot answer your question with regard to who picks up the additional cost. Typical specifications require that the electrical contractor ensures that the installation is NEC-compliant. When violations are found on engineered drawings, they must immediately be brought to the attention of both the engineer and the owner.
We are having an issue with the AHJ over a residential A/C compressor. The inspector is saying we cannot use a 40-amp (A) OCPD on No. 10 (NM) Romex. The compressor nameplate states the minimum circuit ampacity is 21.6A, with a maximum fuse or breaker size of 40A. We believe we are well within the NEC. Can you please help?
The electrical inspector is correct. In general, a 10 AWG copper conductor requires overcurrent protection that does not exceed 30A. As seen in your question, the nameplate on the compressor permits overcurrent protection not to exceed 40A. Using type NM cable, this would require an 8 AWG copper conductor that is rated at 40A. The general rule for the protection of conductors in Section 240.4 requires protection in accordance with the conductor ampacity in Section 310.15, unless otherwise permitted in 240.4(A) through (G). Section 240.4(D) provides requirements for small conductors. The maximum overcurrent protection for 10 AWG copper is 30A unless 240.4(E) or (G) apply. 240.4(E) provides a list of six tap conductor requirements that do not apply in this scenario. Section 240.4(G) provides a table for the Code user to reference requirements in other articles for specific conductor applications.
Requirements in Article 440 are referenced but do not apply in this scenario. Residential air conditioning compressors are located outdoors. Type NM cable is not permitted to be installed outdoors. Section 334.12(B)(4) prohibits type NM cable installation in damp or wet locations. See Section 300.9, which clarifies that raceways installed outdoors above grade are considered to be a wet location. This means that type NM cable cannot be installed in a raceway to a compressor installed outdoors.
Communications cable and lightning conductors
An electrical inspector required us to relocate multiple communications cables because they were too close to lightning conductors. We installed these cables before the lightning conductors were installed. Our contract involved only pulling the cable, and since the cables were not terminated, we were able to pull back some slack and provide over 6 feet of separation. Is this a requirement?
Yes, Section 800.53 requires that, where practicable, communications wires and cables must maintain a distance of at least 6 feet from lightning conductors. It is important to note to use of the term “where practicable,” which is extremely subjective. A contractor may believe that if the communications conductors had been terminated, it would not have been practicable to relocate them to maintain a 6-ft. separation. The definition of practicable is “able to be done or put into practice successfully,” and the inspector may believe a new cable is required because that is “able to be done.” There is an associated informational note that explains that specific separation distances may be calculated using the sideflash equation in NFPA 780, the Standard for the Installation of Lightning Protection Systems.
Strut-type channel raceway
Can Unistrut be used as a raceway? Power pole installations in a lab we are wiring are noted as strut type raceway. Can we transition with a standard 1½-by-4-in. junction box? How is the strut required to be supported?
Article 384 covers the use, installation and construction specifications of strut-type channel raceway. Section 384.10(4) permits strut-type channel raceway to be used as power poles. Section 384.30 requires securing and supporting at intervals that do not exceed 10 feet and within 3 feet of an outlet box, junction box, cabinet, raceway termination and ends. Strut-type channel raceways and all accessories are required to be listed and identified for use as a raceway. Standard Unistrut is likely not listed for use as a raceway.
Requirements for expansion fittings
As an inspector, I find it easy to apply the requirements of 300.4(H), but how do I make a determination that an expansion fitting is required for compliance with Section 300.7(B)?
Section 300.4(H) requires a listed expansion/deflection fitting for raceways that cross a structural joint that is intended for expansion contraction or deflection. I agree, this requirement is easy to apply because we typically can see structural joints intended for expansion where they are used in bridges, buildings, parking garages or other structures. Section 300.7 applies to raceways that are exposed to different temperatures. Section 300.7(B) requires expansion/deflection fittings where necessary to compensate for thermal expansion, deflection and contraction.
Again, I agree that this requirement is subjective, to some degree. If we were to apply this rule to every raceway that enters or exits every building or structure that is exposed to temperatures that vary from the mid 90°F range to below freezing in Pennsylvania for example, we would certainly see a lot of expansion fittings used. We do not see problems occurring in such situations. However, in areas where there would be more extreme and rapid temperature changes, there is a need for expansion/deflection fittings. For example, there may be industrial environments or research and testing labs where rooms or areas may see significant changes in temperature over a short period of time. The need for expansion/deflection fittings due to exposure to different temperatures must also be based on geographical location. The informational note following 300.7(B) provides the Code user with section references and additional information to aid in making this determination.
Circuit breaker blanks
During our annual safety audit, it was noted that the circuit breaker blanks in multiple panelboards are flimsy and easily dislodged. We ordered the circuit breaker blanks from the manufacturer of the panelboards. I understand that we can use another approved method. What would that be? What else can I use to close the opening and not void the equipment listing?
Unused openings for circuit breakers are required to be closed by Section 408.7, Identified Closures, that was used in this case. Other approved means are permitted, provided that the method used is substantially equivalent to the wall of the enclosure. The blanks that you ordered from the manufacturer are identified for the use. In my opinion, the only other approved means is to add spare circuit breakers. That will provide protection substantially equivalent to the wall of the enclosure.
Emergency electrical disconnect
While I have been an electrician for over 20 years, I was never involved in wiring a gas station. During a recent renovation, my neighborhood gas station installed an emergency disconnect that is readily visible from all of the self-serve gas pumps. Is that a requirement?
Yes, Section 514.11 requires clearly identified electrical disconnects. The required disconnect must remove power to all dispensing devices, remote pumps that serve the dispensing device, all associated power control and signal circuits, and any other electrical equipment in the hazardous location around the fuel dispensing device. Section 514.11 provides requirements for fuel dispensing facilities with an attendant and for those that are unattended (the self-serve gas pumps). The emergency electrical disconnect must be readily accessible to people using fuel dispensers.