- I was recently asked if the NEC covers the conversion of a RV to a food truck. Does it? My friend is anxious to start serving tacos during his trip across North America.
Answer: It does, and it doesn’t!
The NEC would not apply to the installation of any electrical equipment within the food truck since the food truck is an automotive vehicle, and Section 90.2(D)(1) clearly states that the NEC does not apply. But if the wheels were removed and the truck frame was anchored to a foundation, then it becomes a permanent installation. The OSHA 1910 Subpart S Electrical Requirements for electrical safety in the workplace would apply to the taco truck.
The NEC would apply for any temporary installation of a temporary power source for the taco truck in Article 590, especially if a portable generator was used. Sections 250.30 and 230.34 would apply to any portable generator used as a separately derived system to provide power to the taco truck.
- Would the concrete pad shown, which is facilitating the foundation for the EVSE be considered a concrete encased electrode?
Answer: No.
(3) Concrete-Encased Electrode.
A concrete-encased electrode shall consist of at least 6.0 m (20 ft) of either of the following:
-
-
-
- One or more bare or zinc galvanized or other electrically conductive coated rebar of not less than 13 mm (1⁄2 in.) in diameter, installed in one continuous 6.0 m (20 ft) length, or if in multiple pieces, the rebar shall be connected together by steel tie wires, exothermic welding, welding, or other effective means to create a 6.0 m (20 ft) or greater length.
- Bare copper conductor not smaller than 4 AWG
-
-
Metal components shall be encased by at least 50 mm (2 in.) of concrete and shall be located horizontally within that portion of a concrete foundation or footing that is in direct contact with the earth or within vertical foundations or structural components or members that are in direct contact with the earth. If multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.
- Can a GEC be routed within the same raceway as branch and feeder conductors? How about service conductors?
Answer: Yes.
Watch out for the splicing requirement of Section 250.64(C), and the bonding requirement of 250.64(E).
- I am installing a new panel to serve a new tenant finish from an existing service located 35 ft away. The inspector failed my service inspection and stated I would need to provide him with an updated available fault current calculation to determine if the new equipment SCCR was adequate. I told him that I only installed the tenant finish panel equipment and there weren’t any existing fault current labels, does the NEC still require this on existing installations?
Answer: Yes.
Reference: 110.24 (A) & (B), 408.6
Although the service equipment was not replaced an available fault current calculation must be performed to comply with the marking required in 408.6 for the new tenant panelboard unless this is a one or two-dwelling unit.
Section 110.24 – For other than dwelling units, the service equipment must be field marked with the available fault current. Modifications that might impact the available fault current trigger a re-calculation to ensure the equipment ratings meet the site requirements.
Section 408.6 – Requires field marking of the available fault current for switchboards, switchgear, and panelboards in other than one- and two-family dwelling units.
- I failed an inspection for securing 12 AWG NM cables directly to the lower edge of the floor joists. Why on earth is this an issue? It’s a crawlspace for crying out loud! Please tell me there is a Section in the NEC that will help straighten out this inspector.
Answer: Well, as usual the inspector is always right. Reference, 334.15(C).
See NEC 334.15(C) that states:
(C) In Unfinished Basements and Crawl Spaces.
Where cable is run at angles with joists in unfinished basements and crawl spaces, it shall be permissible to secure cables not smaller than two 6 AWG or three 8 AWG conductors directly to the lower edges of the joists. Smaller cables shall be run either through bored holes in joists or on running boards.
- Where a GEC is installed in aluminum EMT, is bonding required at both ends of the raceway?
Answer: No – 250.64(E)(1)
(E)(1) – … Ferrous metal raceways, enclosures, and cable armor shall be bonded at each end of the raceway or enclosure to the grounding electrode or grounding electrode conductor to create an electrically parallel path. Nonferrous metal raceways, enclosures, and cable armor shall not be required to be electrically continuous.
Bonding both ends is necessary with a ferrous raceway used to protect the GEC so that it does not create an inductive choke on the GEC. A choke would limit the current flow which would occur if the GEC is installed in a ferromagnetic raceway and not bonded at both ends. Basically, the raceway acts as an electromagnetic coil (inductor).
Merriam-Webster – Ferrous: of, relating to, or containing iron.
- I recently failed an inspection for not removing a system bonding jumper from a generator. Viewing the photo of the transfer equipment in the next slide, it would appear the feeders from the generator should be considered a separately derived system and the bonding jumper should not be removed. Who is correct?
Answer: The contractor.
It appears that the AHJ has misapplied the NEC requirements to this installation. Let’s look at Informational Note 1 to Section 250.30, An alternate ac power source, such as an on-site generator, is not a separately derived system if the grounded conductor is solidly interconnected to a service-supplied system grounded conductor. An example of such a situation is if the alternate source transfer equipment does not include a switching action in the grounded conductor and allows it to remain solidly connected to the service-supplied grounded conductor when the alternate source is operational and supplying the load served.
The installed transfer equipment does contain a switching action on the grounded conductor to prevent the creation of an objectionable current path, because the generator neutral is bonded to the frame, and the service neutral is bonded in the service equipment. The generator neutral bond is required to remain in place, and an appropriate grounding electrode system is also required to be connected to the generator neutral conductor terminal bar.
- Would the safety switch circled in blue require the minimum working depth as specified in 2023 NEC Section 110.26(A)(1)? What if written procedures for the facility were in place so the air conditioning equipment would never be examined, serviced, maintained, or adjusted while energized?
Answer: Yes.
There was new language added to the charging statement in 110.26 during the 2023 NEC cycle. The first sentence says it all, “Working space, and access to and egress from working space, “shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment.
- My inspector suggested I torque switches and receptacles to include my transition to copper pressure connectors on a project that I was installing new devices originally wired with aluminum, is the Inspector correct?
Answer: I’m not certain that I understand what is being asked, but here is my answer.
Section 110.3(B) ultimately tells us that we must follow instructions (especially with the changes made for the 2023 NEC cycle). Section 110.14 tells us that any termination must be suitable (identified) for the material, and 110.14(D) tells us to tighten (torque) connections to the recommended values from the manufacturer.
- I recently failed an inspection for having splices in free air, commando if you will, or better put, not contained within a box. The splices were for a Class 2 wiring method from a Listed Class 2 power source that was part of a low voltage lighting system assembled from listed parts. Can I tell this inspector to politely go pound sand? The wiring was inside a building, not sure this would change if it were outside.
Answer: Box not required.
References: 725.3, 725.30
A box is not required for Class 2 splices. However, identification of the circuits at the splice is required.
Section 725.3…Only sections of Article 300 referenced apply to Class 2 and Class 3 circuits 725.30 Class 2 and Class 3 Circuit Identification.
Class 2 and Class 3 circuits shall be identified at terminal and junction locations in a manner that prevents unintentional interference with other circuits during testing and servicing.
- Are there different product standard tests and certifications for receptacle assemblies installed on work surfaces and countertops? Follow up; if a receptacle assembly is certified for use in a countertop, can it be used in a work surface with no marking or certifications stating it is suitable for use in a work surface?
Answer: See explanation.
Hard wired receptacle assemblies for use in work surfaces and countertops are UL Listed/Certified as pop-up receptacle assemblies under the product category Receptacles for Plugs and Attachment Plugs (RTRT) located on UL Product iQ at www.ul.com/piq and enter RTRT at the search field. The UL guide information states
Pop-up Receptacle Assembly — An assembly consisting of a retractable flush-mount receptacle, outlet box and flush device cover plate intended for fixed installation on a branch circuit. A pop-up receptacle assembly is suitable for installation in a work surface, kitchen or bathroom countertop. They are provided with one or more receptacle outlets. The outlets are retractable for storage below a counter surface. They are intended for installation in accordance with Sections 210.52(C)(3),406.5(E) and 406.5(F) of the NEC.
Pop-up receptacle assemblies are required to be marked on the device where visible during installation and on the smallest unit shipping carton. “Suitable for installation in a counter top or a similar work surface” or an equivalent wording.
Cord and plug connected assemblies are Listed as Furniture Power Distribution Units (IYNC) and are only investigated for use in mounting to either a portable or stationary furnishing only. These are not for use on fixed cabinets, countertops or work surfaces secured to the building structure.
- I have sleeved a GEC for protection from physical damage and failed my inspection for violating Section 310.3(C) of the 2023 NEC. Really? The inspector cannot be serious, right? I have done this for longer than this inspector has been alive, please tell me I have a code compliant installation. The sleeve just extends down from a cabinet below grade for the bonding of a rod electrode.
Answer: Maybe, see explanation.
310.3(C) Stranded Conductors.
Where installed in raceways, conductors 8 AWG and larger shall be stranded, unless specifically permitted or required elsewhere in this Code to be solid.
250.62 Grounding Electrode Conductor Material. …Conductors of the wire type shall be solid or stranded, insulated, covered, or bare.
250.64(B)(2) Exposed to Physical Damage.
A 6 AWG or larger copper, copper-clad aluminum, or aluminum grounding electrode conductor exposed to physical damage shall be protected in rigid metal conduit (RMC), intermediate metal conduit (IMC), Schedule 80 rigid polyvinyl chloride conduit (PVC), reinforced thermosetting resin conduit Type XW (RTRC-XW), electrical metallic tubing (EMT), or cable armor.
- I recently installed a disconnect switch for a mobile home, the switch enclosure was located 13” above finished grade and my inspector said this violates the minimum required height of the enclosure but could not cite any NEC Section. Is this true and where does it reside in the NEC?
Answer: It is true.
The requirement can be found in Section 550.32(F) Mounting Height. Any outdoor mobile home disconnecting means is required to be installed so that the bottom of the enclosure containing the disconnecting means is not less than 2 feet above the finished grade or working platform, if provided. The maximum height of the center of the grip of the operating handle, when in the highest position, cannot be more than six feet, 7 inches above the finished grade or working platform.
Keep in mind that FEMA flood zone requirements may require the disconnect to be located at least 1 foot above the designated flood level, which could trigger the platform requirements in 110.26(A)(6) the disconnect ended up above the 6’ 7” requirements.
- Can a three-phase GFCI device be used to provide GFCI protection for a single-phase circuit?
Answer: Yes.
Technically you could from a Sq D perspective. However, that product isn’t tested (listed) for the application in the question. The AHJ would have to approve as well.
- Are there systems or equipment we should be concerned with other than Network connected life safety equipment, which may require Cyber security and why is this important?
Answer: Yes, this is a great question, and one that the design community needs to pay special attention to.
Although Sections 110.3(A)(8), 708.7, and 708.8 discuss cybersecurity for the life safety equipment mentioned in the question, Section 240.6(D) covers it as well.
Why is it important? Because a 16-year-old in Mom’s basement may find humor in knocking out a hospital’s substation.
- Could a 208/120-volt, 3-phase automatic transfer switch be used with a 120/240-volt, single-phase standby generator? Specifically, would this change the SCCR marked on the ATS from the manufacturer, or be outside of the voltage rating for which an individual pole of the switch was intended to interrupt?
Answer: No.
Reference: 110.4
No, this ATS would not be permitted unless also marked/listed for 120/240 Volt. An ATS switch is not an overcurrent device intended to open during a fault. The SCCR is a withstand rating and it does depend upon the system voltage. Some ATS units are marked with a voltage range but most are marked with the intended line to line system voltage.
110.4 Voltages.
The voltage considered shall be that at which the circuit operates. The voltage rating of electrical equipment shall not be less than the nominal voltage of a circuit to which it is connected.
- I have just installed a new branch circuit and ran the conductors through the cabinet of a different panel board from where the branch circuits originated. My inspector insists I need to provide a warning label that identifies the closest disconnecting means for the feed through type branch conductors. Crazy much? Is this correct?
Answer: Yes, this is correct. Reference, 312.8(A).
(A) Splices, Taps, and Feed-Through Conductors.
The wiring space of enclosures for switches or overcurrent devices shall be permitted for conductors feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices where all of the following conditions are met:
-
-
- The total of all conductors installed at any cross section of the wiring space does not exceed 40 percent of the cross-sectional area of that space.
- The total area of all conductors, splices, and taps installed at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space.
- The bending space for conductors 4 AWG and larger complies with 28(A)(2).
- A warning label complying with 21(B)is applied to the enclosure that identifies the closest disconnecting means for any feed-through conductors.
-
- I am installing kitchen equipment and was informed that my relays and circuit breakers that provide the required ground fault protection for the equipment must be Listed, is this a new NEC code?
Answer: Section 210.8 requires a listed Class A GFCI protective device.
- I recently installed two rod electrodes roughly 893½’ from the service equipment at a newly constructed building with the only other electrode present being a metallic underground water pipe. Is this cool? Or should I say code compliant?
Answer: Is it cool, NO!
Is it Code Compliant, maybe for the building but not the service! Section 250.24 (E) Grounding Electrode Conductor requires the grounding electrode conductor to be connected at the service equipment, which in this case appears to be located on a pole 893.5 feet away from the building being served. A grounding electrode system for the service equipment meeting the requirements of Section 250.53 for the installation of the grounding electrode, 250.64 for the GEC installation, and 250.66 for the required GEC size is required to be connected to the service equipment.
The 2 rods and metal underground water pipe would meet the requirement in 250.32(A) for the feeder conductors supplying the building from the service equipment and would be connected to the equipment grounding terminal bar in the feeder disconnecting means for the building.
- What would be an example of a listed system of protection against electric shock of personnel for electric vehicle supply equipment? Would a Class A GFCI device satisfy this requirement where required?
Answer: Yes.
However, most EVSE equipment has GFCI protection inside the equipment. If the equipment doesn’t have the GFCI protection built in, then you would protect it with a GFCI breaker at the source.
- Would the image on the left depict a violation of 2023 NEC Section 250.24(B)? This is a step down 480-volt, delta to 120/208-volt, wye transformer. The plans indicated a neutral be supplied with the ungrounded conductors to the transformer.
Answer: Yes.
I love this question! If we assume that the brown, orange, yellow, and gray are the 480-volt, that picture is 100% a violation of 250.24(B). A neutral-to-metal connection is (generally) not permitted after the main bonding jumper or system bonding jumper.
A more common example of this violation occurs when installing the same transformer in reverse (wye-delta).
- I am an inspector who reluctantly approved a sub-panel in a crawlspace of a one-family dwelling, as I could not find any violations when searching through the NEC. I have been having nightmares, and flashbacks ever since. Is there an NEC Section that would have supported my disappointment in this electrician’s decision to place a sub-panel in a crawlspace?
Answer: Maybe.
Reference: 110.26
Answer: The installation of a panelboard within a crawlspace may not comply with the working space requirements. In particular, the 2m (6-1/2ft) working space height is probably an issue.
- Are there currently any product standard evaluations or testing methods for the grounding and bonding performance of concentric and eccentric knockouts for cabinets, cutout boxes and meter socket enclosures?
Answer: No.
No, not for cabinets, cutout boxes and meter socket enclosures. You would have to bond around them in accordance with NEC 250.92 for services or 250.97 over 250V application or 250.96 for other enclosures.
Only Listed Metallic Outlet Boxes (QCIT) concentric and eccentric knockouts have been evaluated for bonding over and under 250V and may be marked as such. See UL Product iQ. www.ul.com/piq enter QCIT at the search field.
- Are Surge protective devices required for fire alarm control panels? And if so where specifically can they be installed?
Answer: Yes. Location on the supply side of fire alarm control panel.
760.33 Supply-Side Overvoltage Protection.
A listed surge-protective device (SPD) shall be installed on the supply side of a fire alarm control panel in accordance with Part II of Article 242.
First Revision No. 9524
Committee Statement: Fire alarm control panels contain electronics that can be damaged by surges appearing on the supply side of the equipment. Providing overvoltage protection can increase the reliability of an installation. The panel added the new section after 760.32 as new 760.33. 760.32 covers NPLFA and PLFA circuits that leave the building, including overvoltage protection for these circuits. Having these requirements in sequence adds to the usability of the Code.
- Would the Certificate of compliance as required by NEC 240.6(D)(2)b for remotely accessible adjustable–trip circuit breakers also include the date & final AHJ approvals prior to being placed into service?
Answer: No.
Section 240.6(D)(2)(b) requires that documentation of the cybersecurity assessment and certification for network connected remotely accessible adjustable trip circuit breakers must be made available to those authorized to inspect, operate, and maintain the system, but does not require a date or final AHJ approval to be part of that documentation.
NEMA Guideline Document, NEMA CY 70001-2023 Cybersecurity Implementation Guidance for Connected Electrical Infrastructure, which can be downloaded for free, does contain some guidance on what the documentation should include.
The documentation recommended when demonstrating cybersecurity compliance for examination, evaluation, risk assessment, or certification will be dependent on the type of product/system as well as the infrastructure’s standard requirements. One or more of the following should be provided:
-
-
- A letter issued by the manufacturer that indicates the product/system has been examined or evaluated to a certain cybersecurity standard.
- Documentation stating utilization of a Secure Development Life Cycle that places security front and center during the product development.
- Risk Assessment document for the system and any recommendations from the risk assessment.
- Testing compliance/certification via manufacturer’s declaration or a Nationally Recognized Testing Laboratory
-
- I recently failed an inspection for the following installation on the left. This is a sub-panel, and the year is 2023, why is the inspector insisting I need a bonding conductor between my equipment grounding conductor terminals. Is the inspector correct?
Answer: No. 250.109 Metal Enclosures.
Metal enclosures shall be permitted to be used to connect bonding jumpers or equipment grounding conductors, or both, together to become a part of an effective ground-fault current path. If installed, metal covers, plaster rings, extension rings, and metal fittings shall be attached to these metal enclosures to ensure an effective ground-fault current path or shall be bonded with bonding jumpers or equipment grounding conductors, or both.
- I am an inspector who recently failed a PV installation because the PV contractor elected to interconnect the power source conductors to feed through conductors from a 200-ampere main panel. The feed-through conductors are #3 AWG copper and supply an indoor main breaker type 100-ampere sub-panel. Wouldn’t this violate 2023 NEC Section 240.21? Specifically, where it states, “Conductors supplied under 210.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.”
Answer: Yes.
Great question (by that I mean a hard question). This is a violation of 240.21, as the question indicates. The 3 AWG conductors are protected by a 200A circuit breaker and are therefore a feeder tap. A feeder tap is not permitted to supply another circuit that doesn’t comply with 240.4 (taps may not be tapped).
- Would a sewage ejector be considered a sump pump? I have wired a receptacle for an ejector located in an area where the receptacle is not required to be GFCI protected, however my lovely inspector is telling me the ejector requires GFCI protection per Section 210.8(D)(6). Who is correct?
Answer: Inspector.
Reference: 210.8(D)(6).
The inspector is correct. The requirements of this section would apply to any pump installed in a sump basin. See the Merriam-Webster definition for sump pump.
The ejector pumps are usually installed in a sump basin and the potential hazard is the same.
- Do Fire Alarm System Detection devices, such as horns, & strobes installed in pool equipment rooms have to be identified as suitable for a corrosive environment, and where is it stated in the NEC?
Answer: Yes, it is a corrosive environment. Reference, 680.14(B) & 760.3(C).
They must suitable and identified for use in the environment.
- I recently failed an inspection for violating 2023 NEC Section 110.10. Please help, the calculated fault current available at the panelboard is 13,487-amperes. All circuit breakers are marked 22k AIC. My inspector says based on the panelboard manufacturer label shown in the next slide, fully rating each feeder and branch breaker does not help me. Is the inspector correct?
Answer: Maybe, see explanation.
When a panelboard has through-feed or sub-feed lugs, the SCCR of the panelboard is based on the upstream overcurrent protective device. The branch circuit breakers do not assure proper protection of the panelboard bus structure. As noted on the label in the second slide, it references the “series rating manual.” Review of the series rating manual reveals the upstream circuit breaker protecting the panelboard will determine the SCCR of the panelboard.
So, the long and short of it is that the SCCR of this panelboard depends upon the Interrupting Rating of the upstream overcurrent protective device.
- I just failed my inspection, and oh boy am I angry about this one. I have installed a new branch circuit from an existing panelboard located in a Wendy’s restaurant. The inspector has the nerve to tell me, the installation is gorgeous, and then hands me a correction notice which reads, “branch-circuit OCPD’s cannot be in the bathroom, see Section 240.24(E) of the 2023 NEC.” Is this for real?
Answer: The AHJ is for real.
The AHJ is very real, and so is the Code text as it applies to the 2023 NEC. Section 240.24(E) clearly states that OCPDs shall not be located in bathrooms, showering facilities, or locker rooms with showering facilities. The new OCPD for the new branch circuit will have to originate from a panelboard that is not located in a bathroom.
Stay tuned for the 2026 NEC as CMP-10 may be addressing this topic!
- Is there a limit to the number of cables or raceways that can be supported by a single ceiling wire? Assume the ceiling wire is installed for the sole support of raceways and cables only, not the suspended ceiling system.
Answer: I’m assuming the installation is regarding 300.11(B)(1) or (2).
Generally, the rule for supporting electrical equipment is that the equipment must be “securely fastened in place.” This phrase means not only that vertical support for the weight of the equipment must be provided but also that the equipment must be secured to prevent horizontal movement or sway. What that means the support wires are only as good the rating of the wire as far as how much that support wire rating.
- Does the NEC require SPGFCI devices to have an SCCR rating? I have only recently discovered receptacle SCCR rating requirements in some control panels using UL508 evaluation criteria.
Answer: Yes.
The NEC does not specifically require an SCCR rating for a GFCI or SPGFCI device, but that is the case for most equipment too. Section 110.10 always applies, however, and that section requires all equipment to (ultimately) be rated for the fault current.
- Can parallel feeders be tapped? If so, do I need to tap each individual set of the parallel feeders? I believe for my purposes tapping just one set of the parallel installation should do the trick.
Answer: Yes, but…
Reference: 300.3(B)(1)
Paralleled conductor sets can be tapped. However, the tap must connect to all conductors of the paralleled set, grounded and ungrounded, as applicable. The paralleled conductor sets function as one large conductor so a tap connection must include all.
- Are bonding fittings required at both ends of a raceway containing service entrance conductors where the raceway enters each cabinet through concentric KO’s? One cabinet is for the utility CT’s and the other is for the main service panel board. Does the answer change where the neutral is utilized as described in 2023 NEC Section 250.142(A)(1) for the cabinet on the supply side of the service disconnect?
Answer: Yes, for part one and part two will depend on system voltage, see explanation.
Yes, for part one of the question see NEC 250.92(B) for methods of bonding at a service around concentric and eccentric knockouts.
For part 2 of the question and the reference to 250.142(1), where the grounded conductor bonds the CT cabinet and then the main panelboard, only one side of the conduit needs a bonding bushing, unless it is a 277V/480V service. Then since the voltage would exceed 250V to ground, you would need to bond both ends of the conduit with a bonding bushing per 250.97.
- Does all of NEC Article 680, Part V apply to splash pads?
Answer: Splash Pads must comply with Parts I, V and 680.26 in Part II. Reference Section 680.50 & 680.50(A)(2).
- I failed my inspection for installing a standard resistance type room heater in a pool equipment room. The inspector stated it needed to be listed for the now recognized corrosive environment. Is he correct?
Answer: Section 90.4 would indicate the AHJ is correct.
Section 90.4 states that the AHJ is always correct! First, we need to know what is considered a corrosive environment, and Article 100 provides the following definition, areas or enclosures without adequate ventilation, where electrical equipment is located and pool sanitation chemicals are stored, handled, or dispensed. So, if the pool equipment room also has pool sanitation chemicals that are stored, handled, or dispensed and the ventilation is not deemed adequate by the AHJ, we have a corrosive environment.
Section 680.14 Corrosive Environments covers wiring methods in (A) and Other Equipment in (B). The “standard resistance type room heater” falls under (B) here, and (B) requires that other equipment must be suitable for use in corrosive environments or be installed in an identified corrosion-resistant enclosure. Equipment that is listed for pool and spa use, is to be considered suitable for this use.
- Would the image on the left depict a violation of 2023 NEC Section 110.26? Specifically, the panelboard cabinet equipment door, when opened, impedes the building code required egress path for this bedroom within an apartment complex.
Answer: Maybe. 110.26 Spaces About Electrical Equipment.
Working space, and access to and egress from working space, shall be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment. Open equipment doors shall not impede access to and egress from the working space. Access or egress is impeded if one or more simultaneously opened equipment doors restrict working space access to be less than 610 mm (24 in.) wide and 2.0 m (61⁄2 ft) high.
- What is the minimum distance the NEC requires a luminaire to be located from a fuel dispenser? The dispenser is not located on the property of a repair garage.
Answer: Depends.
Assuming we are talking about a flammable liquid (gasoline) and not a combustible liquid (diesel), the answer lies in Section 514.4, which points us back to Article 501 for classified locations. Within the classified location, the luminaire would need to comply with 501.130, but the classified location near a dispenser is very small. It would be hard to violate the requirements.
- I am installing a new 3-phase 208 VAC branch circuit in a corrosive environment and have some left-over wiring from a previous job. Would the code allow me to mix 3 aluminum phase conductors with the NEC section 680.7 required EGC copper conductor?
Answer: Yes.
Reference: 680.14, 110.14(A), 310.3(B)
Yes. However, the wiring method and equipment must be suitable for use in a corrosive environment.
Wiring methods are: Rigid metal conduit, intermediate metal conduit, rigid polyvinyl chloride conduit, reinforced thermosetting resin conduit, and liquidtight flexible nonmetallic conduit.
Other items:
-
-
- Terminations identified for AL
- Conductors are AA-8000 alloy
- Conductor size
-
- Would the circled area in the photo on the left be considered countertop space per 2023 NEC Section 210.52(C)? The countertop is greater than 12” wide?
Answer: I would say no.
That is not a wall line as referenced in NEC 210.52(C)(1), that is in front of a cabinet resting on the countertop and the swing of the cabinet door would reach out to the end of the countertop. No electrical product would be installed in front of that cabinet door.
- Where electric service and electrical maintenance are provided by the building management and where these are under continuous building management supervision. Does this phrase mean the building has qualified electricians on staff or just a knowledgeable maintenance person?
Answer: See Sections 230.72, & 225.31, and the definition for qualified person in Article 100.
230.72 Grouping of Disconnects. (C) Access to Occupants.
Exception: In a multiple-occupancy building where electric service and electrical maintenance are provided by the building management and where these are under continuous building management supervision, the service disconnecting means supplying more than one occupancy shall be permitted to be accessible to authorized management personnel only.
225.31 Disconnecting Means.(B) Location.
Exception No. 1: For installations under single management, where documented safe switching procedures are established and maintained, and where the installation is monitored by qualified individuals, the disconnecting means shall be permitted to be located elsewhere on the premises.
- I am supplying a detached garage sub-panel with outside feeders supplied from a 50-ampere breaker, the sub-panel supplies a single 15-ampere lighting branch circuit and two-twenty ampere receptacle outlet circuits. The electrical inspector handed me a correction report stating, “code requires a 60-amp minimum”, can you translate please?
Answer: Appears the AHJ is confused.
It appears that the AHJ is confusing the minimum size rating for a feeder disconnecting means in Section 225.39(D), which requires the feeder disconnecting means to be rated for a minimum of 60A, with the minimum conductor sizing for a feeder in 215.2(A). If a load calculation can justify the installation of a 50A feeder to the detached garage, then the 50A feeder is required to be terminated onto a feeder disconnecting means that is rated for at least 60A.
- Would the image on the left depict a violation of 2023 NEC Section 250.52(B)(1)? My inspector informed me to bond my gas pipe here because there is CSST in the house. What is becoming of this world, and what is CSST?
Answer: Yes.
250.52(B)(1) does not allow metal underground gas piping systems to be used. To properly bond Corrugated Stainless-Steel Tubing (CSST) the installer must bond to the manufacturer installation instructions.
- How far does code require an air conditioner to be from the inside wall of an in-ground swimming pool? 5 feet or 10 feet per 680.22 (D) or (E) either one could apply?
Answer: See explanation.
Interesting question. We know that it must be at least 5’ due to 680.22(E), which applies to equipment that is not connected to an outlet and isn’t covered by the other items in 680.22 (such as a transformer, meter socket enclosure, communications outlet, or similar). Section 680.22(D) does not say “equipment connected to (or supplied by) an outlet”, although perhaps it should. It just says “other outlets shall be not less than 10’…”
- I just completed an industrial process installation and noticed the equipment nameplate data was located inside the primary control cabinet, is the installer allowed to simply duplicate a 110.21 compliant machine nameplate data label to the outside of the control equipment enclosure that is visible after installation or would it have to come from the manufacturer?
Answer: Installer could duplicate the nameplate info.
Reference: 670.3(A), 409.110
The code would permit the installer to duplicate the nameplate information for a label on the outside.
Industrial machinery and industrial control panels are not required to listed. A listed product will have the nameplate information and location based on the standard but this would not prevent duplicate information to be provided on the outside of the equipment.
- Regarding the previous installation of industrial process equipment, the inspector also requested that the Available short-circuit current also be labeled. I told him some equipment was replacement only and there weren’t any existing fault current labels, does the NEC still require this on existing installations?
Answer: I would say yes.
You need to comply with NEC 110.24(B) specifically references when modifications are made. “When modifications to the electrical installation occur that affect the available fault current at the service, the available fault current shall be verified or recalculated as necessary to ensure the service equipment ratings are sufficient for the available fault current at the line terminals of the equipment.”
- GRC raceway containing service entrance conductors connected to a cabinet with drilled holes, scraped paint, bushings and double bonding lock nuts at a meter housing and main panel. The inspector failed me for not having an additional listed bonding method (grounding bushings). Is he smoking too much pot? We are in Colorado after all.
Answer: It may be the pot, see explanation.
-
- Bonding equipment to the grounded service conductor by an applicable method in 8(A)
- Connections made up wrenchtight using threaded couplings, threaded entries, or listed threaded hubs on enclosures
- Threadless couplings and connectors if made up tight for metal raceways and metal-clad cables
- Other listed devices, such as bonding-type locknuts, bushings, or bushings with bonding jumpers
Link Enhanced Content: Bonding-type locknuts and grounding and bonding bushings for use with rigid or intermediate metal conduit are provided with means (usually one or more set screws that make positive contact with the conduit) for reliably bonding the bushing and the conduit on which it is threaded to the metal equipment enclosure or box.
- When measuring for the receptacle outlet required per 210.52(C)(1), does the measurement begin from the wall line as shown in the photo on the left?
Answer: I would say it does not.
Section 210.52(C) Countertops and Work Surfaces states that in kitchens, pantries, breakfast rooms, dining rooms, and similar areas of dwelling units, the receptacle outlets for countertop and work surfaces that are 300 mm (12 in.) or wider shall be installed in accordance with the Section 210.52(C)(1) Wall Space requirements. The key word here is “wider” which is a horizontal measurement along the back of the countertop or worksurface. Width is defined as the side-to-side distance or length of the item that’s touching or stretches across the wall. Depth is defined as the back to front distance or length it comes out from the wall and into the room. There is no NEC measurement requirement for the depth of a countertop or worksurface. So, a receptacle that is within the first 24” wall space horizontally along the wall space is sufficient to meet the requirement.
- Can GEC conductors be paralleled, and the sum of the parallel runs be equal to or greater than the minimum size required per 250.66?
Answer: NO. The code doesn’t mention the GEC in the charging statement. 310.10(G) (1) General.
Aluminum, copper-clad aluminum, or copper circuit conductors for each ungrounded conductor, grounded conductor, or neutral conductor shall be permitted to be connected in parallel (electrically joined at both ends) only in sizes 1/0 AWG and larger and shall be installed in accordance with 310.10(G)(2) through (G)(4).
It would need to be sized in accordance with table 250.66.
- Could the AHJ require the marking as required in 750.30(C)(4) be a graphic Map placed on the Energy Management System? The system was going to be designed to remove the newly added EVSE load on either the service or feeder conductors.
Answer: Graphic map? No.
I’m not sure what a graphic map” is, but it sounds like a lot more than the required markings in 750.30(C)(4).
In North Korea, the AHJ can require whatever they want. In the US, we don’t enforce laws that aren’t really laws.
- I have installed a self-contained hot tub for aboveground use; the top rim of the hot tub is 1’ above an adjacent concrete patio. The inspector has failed me for never having a perimeter surface bonding inspection per 680.26(B)(2) for the adjacent concrete patio. C’mon man, I’m not sure where the City of Arvada is finding their electrical inspectors these days. Is the inspector correct?
Answer: Yes, the inspector is correct.
The equipotential bonding of perimeter surfaces can only be omitted if all of the following requirements are met:
-
-
- Listed as a self-contained spa for aboveground use
- Not identified only for indoor use
- Installed according to manufacturer’s instructions on or above grade
- Top rim of the spa must be 28in. above all perimeter surfaces that are within 30in. Horizontally from the spa
-
- I have compact stranded 250 kcmil aluminum service conductors, what size GEC is required to bond to the metallic underground water pipe electrode?
Answer: 4 AWG copper, or 2 AWG aluminum
A No. 4 copper or 2 aluminum, would be required for 250 kcmil Aluminum service entrance conductors. Table 250.66 does not differentiate standard stranding from compact stranding.
- I was recently informed that the Power supply to premise wiring systems per NEC section 710.15 (A) was generally supplied by “Firm” sources such as Generators and ESS. Does the NEC allow the entire premise wiring system capacity load to be calculated using both firm and variable sources?
Answer: Yes, reference Section 710.15(A) Supply Output.
Power supply to premises wiring systems fed by stand-alone or isolated microgrid power sources shall be permitted to have less capacity than the calculated load. The capacity of the sum of all sources of the stand-alone supply shall be equal to or greater than the load posed by the largest single utilization equipment connected to the system. Calculated general lighting loads shall not be considered as a single load.
Informational Note:
For general-use loads the system capacity can be calculated using the sum of the capacity of the firm sources, such as generators and ESS inverters. For specialty loads intended to be powered directly from a variable source, the capacity can be calculated using the sum of the variable sources, such as PV or wind inverters, or the combined capacity of both firm and variable sources.
- Do conductor terminations need to be certified/listed for use with DC where the source is DC?
Answer: Maybe.
Maybe in the product listing standards depending on the type of equipment, termination, or connection, but there is no explicit requirement in the NEC. PV dc mating connectors that are listed under UL 6703 “Connectors for use in PV Systems” contains listing requirements for dc mating connectors. UL 489 “Molded-Case Circuit Breakers, Molded-Case Switches and Circuit-Breaker Enclosures” allows the same terminals used on “ac” circuit breakers to be used in the manufacturing of “dc” circuit breakers. The overall listing of the “dc” circuit breaker covers the terminals.
- Would the service entrance conductors depicted in the photo be considered outside the building? The service conductors are installed in RMC.
Answer: Maybe. 230.6 (5) Conductors Considered Outside the Building.
Conductors shall be considered outside of a building or other structure under any of the following conditions:
(5) Where installed within rigid metal conduit (RMC) or intermediate metal conduit (IMC) used to accommodate the clearance requirements in 230.24 and routed directly through an eave but not a wall of a building.
- When sizing a generator for optional backed up loads for a home, would I utilize NEC Article 702 or 710? Does the generator really need to be sized for the total calculated standby loads?
Answer: Article 702
Article 710 is only used for a stand-alone system, which is a system that is not connected to a power production/distribution network (like a utility). Hopefully Article 710 will be deleted soon, because I don’t know that it even needs to exist.
Article 702 applies, 702.4 tells us about capacity and rating. You must size the generator based on the type of transfer equipment, but 220.87 can be used.
- I noticed that Section 705.13 was replaced with a new term, Energy Management Systems, which references Section 750.30. Was there a reason that the informational note in 705.13 was not also referenced in 750.30 to further clarify PCS products as a type of EMS?
Answer: Yes.
Reference: Article 100 Energy Management Systems
The definition of EMS was revised to encompass both the control of loads and/or power production sources or energy storage. The informational note was placed in 705.13 to assist the code user with the transition from the term PCS to EMS.
- Are hospital grade type receptacles required in the patient care areas of a dental office?
Answer: See explanation.
A dental office would be considered a Category 3 Space (Category 3). As defined in Article 100 as
Space in which the failure of equipment or a system is not likely to cause injury to patients, staff, or visitors but can cause discomfort. [99:3.3.140.3] (517) (CMP-15)
Informational Note:
These spaces, formerly known as basic care rooms, are typically where basic medical or dental care, treatment, or examinations are performed. Examples include, but are not limited to, examination or treatment rooms in clinics, medical and dental offices, nursing homes, and limited care facilities. [99:A.3.3.140.3]
There are no requirements in Article 517 for Category 3 Space for receptacles to be hospital grade receptacles.
The only exception would be if they have receptacles in an anesthetizing location in accordance with NEC 517.61 (A), (B), or (C).
- Do I need a wire type EGC in addition to MC with armor qualifying as an EGC from a switch outlet located in the patient care area supplying a lighting outlet located seven and a half feet above the floor?
Answer: Yes, a wire type EGC is required, see Section 51713.
- What are some of the major differences in regard to product standard testing for connectors certified for use on the supply side of service equipment as compared to those that are not approved for use on the supply side of service equipment?
Answer: See explanation.
The location of the OCPD being on the load side of the connector instead of the line side during the short-circuit current test.
For power distribution blocks, the UL 1953 Outline of Investigation for Power Distribution Blocks requires the power distribution blocks to be subjected to a short-circuit test with an OCPD connected to the load-end of the power distribution block exceeding at a minimum 10,000-amperes of fault current. The testing shall comply with the short-circuit test requirements in the UL 1059 Standard for Terminal Blocks.
For pressure connectors, Annex H of the UL 486A-486B Standard for Wire Connectors sends the manufacturer to additional test requirements in one of 3 NEMA/ANSI Standards.
NEMA/ANSI C119.4 Electric Connectors—Connectors for Use Between Aluminum-to-Aluminum and Aluminum-to-Copper Conductors Designed for Normal Operation at or Below 93°C and Copper-to-Copper.
NEMA/ANSI C119.5 Electric Connectors—Insulation-Piercing Connector Systems, Rated 600 V or Less.
NEMA/ANSI C119.6 Electric Connectors—Non-Sealed, Multiport Connector Systems Rated 600 V or Less for Aluminum and Copper Conductors.
- Are standard interior wall receptacles allowed to be located behind sliding barn doors?
Answer: Yes, they are permitted in other than dwellings, and required if installed in a dwelling. 210.52(A)(2)
General Provisions.
In every kitchen, family room, dining room, living room, parlor, library, den, sunroom, bedroom, recreation room, or similar room or area of dwelling units, receptacle outlets shall be installed in accordance with the general provisions specified in 210.52(A)(1) through (A)(4).
-
-
- Receptacles shall be installed such that no point measured horizontally along the floor line of any wall space is more than 1.8 m (6 ft) from a receptacle outlet.
- Wall Space. As used in this section, a wall space shall include the following:
- Any space 600 mm (2 ft) or more in width (including space measured around corners) and unbroken along the floor line by doorways and similar openings, fireplaces, stationary appliances, and fixed cabinets that do not have countertops or similar work surfaces
- The space occupied by fixed panels in walls, excluding sliding panels
- The space afforded by fixed room dividers, such as freestanding bar-type counters or railings
-
- Are any of the CMP members aware of any new Flow Battery or Flywheel type ESS system manufacturers that are presently available for Residential applications?
Answer: Ryan Jackson is not aware of any.
Any CMP members? I don’t know, but this one is not aware of any.
That was easy!
- Per the 2023 NEC, are tamper resistant receptacles required in restaurants?
Answer: No.
Restaurants are not locations requiring TR
Locations that require tamper-resistant receptacles:
All dwelling units, boathouses, mobile homes and manufactured homes, including their attached and detached garages, accessory buildings, and common areas
-
-
- Guest rooms and guest suites of hotels, motels, and their common areas
- Child care facilities
- Preschools and education facilities
- Within clinics, medical and dental offices, and outpatient facilities, the following spaces:…
- Places of awaiting transportation, gymnasiums, skating rinks, fitness centers, and auditoriums
- Dormitory units
- Residential care/assisted living facilities, social and substance abuse rehabilitation facilities, and group homes
- Foster care facilities, nursing homes, and psychiatric hospitals
- Areas of agricultural buildings accessible to the general public and any common areas
-
- Dear Tom Lichtenstein. Can you please tell me if the alteration made to the designed wireway for service conductors in the meter/main combo cabinet pictured on the left would be acceptable per the products certification/listing?
Thanks,
Go Packers!
Answer: No.
No, the modification of the UL Listed meter main would not be acceptable unless the modification was investigated under a UL field evaluation and found in compliance with UL’s requirements and the product was labeled with a UL field evaluation label.
The UL Listing/Certification mark indicates that when the product left the factory it was in compliance with UL’s requirements at the time of manufacture. If the product is modified after it leaves the factory UL does not know if the product continues to comply with UL’s requirements unless the modifications are evaluated under a UL Field Evaluation,
For more information on UL’s field evaluations, contact UL’s Customer Service at 877-854-3577, #2 or www.ul.com/field.
- What is the minimum size supply side bonding jumper required at a connection cabinet line side of the electrical service if 11 parallel sets of 750 kcmil are installed? The connection cabinet is on the premises wiring side of the service point as determined by the serving utility.
Answer: 2/0 copper, where individual SSBJ’s are utilized for each raceway or cable, or a 750KCMIL SSBJ utilized to bond all raceways or cables.
- Does code allow a brass colored 10-32 screw installed in a metal electrical box for the termination of an EGC, or EBJ?
Answer: Yes.
For equipment grounding conductors or equipment bonding jumpers, as Section 250.8 covers the requirements for the connection of equipment grounding conductors, grounding electrode conductors, and bonding jumpers, and list item (5) requires any machine screw-type fastener to engage not less than two threads or be secured with a nut. The word “green” does not appear in any of the list items, so a green colored screw is not required. In fact, the ground screw doesn’t even have to be listed!
Section 250.28(B) requires main bonding and system bonding jumper screws to be “green” in finish, but that section does not apply here.
Section 250.126 requires the terminal for the connection of the equipment grounding conductor on a wiring device to be green, but again this section does not apply here.
Section 250.119(A) requires insulated or covered equipment grounding conductors to be green.
The reason why so many ground screws are green is because this is done for visibility purposes within the enclosure. A green ground screw is nice “eye candy”, but it is not a NEC requirement.
- On what side of an outdoor metal electrical enclosure should a wet location sealable locknut be installed? Outside the enclosure or inside, maybe both sides?
Answer: Either
Sealing (Liquid-tight) Locknuts — are Listed under the product category Conduit Fittings (DWTT) on UL Product iQ at www.ul.com/piq and enter dwtt at the search field. The guide information for Conduit Fittings (DWTT) states:
Sealing (Liquid-tight) Locknuts – Sealing locknuts are intended for use with threaded rigid metal conduit and intermediate metal conduit with one sealing locknut on the outside or the inside and either an ordinary locknut or sealing locknut on the inside of the enclosure for wet locations or liquid-tight applications. Sealing locknuts may also be used with certified wet location or liquid-tight fittings where so marked on the fitting carton and used on the inside of the enclosure.
- Regarding 706.20 (C) (1) Spaces about ESS installations, does the current code clarify protection from vehicular damage when located within a Residential Garage?
Answer: Equipment shall be protected from physical damage.
Section 706.20(C)(1) is for working space, not protection from physical damage. But 110.27 still applies, and it requires damage protection for all electrical equipment that is subject to physical damage. In a garage… do your best. You can’t stop a car from hitting something. Never underestimate the power of bad drivers!
- What is the minimum calculated load for a single 16 kW range?
Answer: 9.6kW.
Reference: 220.11(C), 220.55 & Table 220.55
For a single range, Column C would indicate a load of 8 kW but that is only valid for ranges up to 12 kW. Note 1 provides a correction factor of an additional 5% for each kW above 12 kW. In this case the range is 4 kW over so the correction adds another 20% load for a total load of 9.6 kW.
- My inspector failed me for terminating Type 2 SPD line conductors ahead of the service disconnecting means and is requiring me to install the conductors to a circuit breaker within the service equipment bus bars. Is this a requirement in the NEC, does he not know how expensive circuit breakers are?
Answer: See 110.3(B) and explanation.
Type 2 SPD’s limited in NEC 242.12 to the load side of service overcurrent device. This is also an NEC 110.3(B) issue.
UL Lists/Certifies SPD’s under the product category Surge-protective Devices (VZCA). You can locate the guide information and certifications for this category on UL Product iQ at www.ul.com/piq and enter the category code VZCA at the search field.
The VZCA guide information details the definition of each type of SPD as follows:
Type 1 — Permanently connected SPDs intended for installation between the secondary of the service transformer and the line side of the service equipment overcurrent device, as well as the load side, including watt-hour meter socket enclosures and intended to be installed without an external overcurrent-protective device.
Type 2 — Permanently connected SPDs intended for installation on the load side of the service equipment overcurrent device, including SPDs located at the branch panel.
Type 3 — Point-of-utilization SPDs, installed at a minimum conductor length of 10 m (30 ft) from the electrical service panel to the point of utilization, e.g., cord-connected, direct-plug-in, receptacle-type and SPDs installed at the utilization equipment being protected. The distance (10 m) is exclusive of conductors provided with or used to attach SPDs.
- Can a microgrid system supply a single structure or dwelling? Or is the intent of a microgrid system to supply multiple structures or dwellings?
Answer: There is no limitation. See the definition for Microgrid in Article 100, and Sections 517.30(B)(5), 517.40(C), 700.12(H), 701.12(G), & Part II of Article 705.
- Is there a reference to the ICC IRC & IBC Code books in Article 706 or other sections of the 2023 NEC. Given the new ESS changes in Section R328, why wouldn’t they be included in Section 706.1 Informational Notes?
Answer: No.
No, but CMP-13 looks forward to your public input for the 2029 Edition of the NEC! The NEC is not the only installation code as it applies to the installation of electrical equipment. The IBC, IFC, IRC, IFGC, IMC, and IECC all contain installation requirements that have impact on how electrical equipment must be installed. The NEC purview with an ESS is with the electrical connection of the ESS, and not with fire protections, vehicle impact protections, UL 9540A thermal runaway testing, and size and capacity requirements. There is an Informational Note to NFPA 855 in the scope of 706.1, and the 2027 I-codes are in the process of having pointers to the requirements in NFPA 855 for ESS. The ESS installation requirements in NFPA 855 are copied in Section 1207 in the IFC for commercial installations, and Section R328 in the IRC. A lot of the same installation requirements are required to be in the ESS installation manual in accordance with Section 42 of the UL 9540 Standard for ESS.
- Can a 5KW ESS with a max output of 20.83 amps with 10awg THHN wires back feed a 200-amp main service to a dwelling when the primary source is lost?
Answer: Maybe.
This is an optional standby question. The question is missing a number of key details. Back feeding the utility when there is a loss power is dangerous and a code violation. If the installation has an automatic transfer switch as the service equipment, then the answer is No. The source must have the capacity for all automatically connected loads. If some type of manual transfer equipment is used, then this could be done if the other installation requirements are met.
Also see, I see in 702.4(A)(2) where it address’s Energy Storage that is installed with an automatic transfer that it needs to be able to service the full load or you install a energy management system.
- I was failed for not having a plainly visible nameplate for an exterior Residential ESS installation. The Unit Information however was located under the Nema-3R cover, would this comply with Section 706.4 or is it solely an AHJ interpretation and final decision?
Answer: AHJ decision
Ultimately it is up to the AHJ, but I personally think it is a bit excessive to prohibit it from being behind the cover of a Type 3 enclosure. It’s not a warning label.
However… I can be easily persuaded to change my mind. This is the beauty of classes like these. We are all learning together!
- Article 706 now requires maintenance & records be kept for ESS systems excluding 1 & 2 family dwellings would this be the contractor’s responsibility after installation, and should we prepare for the possibility of new Equipment Preventative Maintenance programs being codified
Answer: See explanation.
Reference: 706.7
The safety of the electrical system is contingent upon regular service and maintenance. Energy Storage Systems require additional diligence during the entire product life cycle from installation to decommissioning and recycling. This is particularly true for Li-ion based systems.
Page 17Public
The personnel performing these activities need specific training from the manufacturer so the contractor may or may not be qualified for this work.
Baseline data for the system maintenance and service is gathered at installation and commissioning. NFPA 855 requires a maintenance plan and records starting at installation.
- Can the air conditioning service receptacle outlet required per 2023 NEC Section 210.63(A) be on a multi-wire branch circuit that also supplies the air conditioner? If yes, is the receptacle outlet permitted on the load side of the equipment’s branch circuit disconnecting means?
Answer: No.
NEC Section 210.63(A) for HVAC equipment specifically prohibits the receptacle outlet shall not be connected to the load side of the equipment’s branch-circuit disconnecting means.
The receptacle should be on a different circuit so that you can use the live receptacle to power tools for safely servicing the HVAC equipment while the HVAC equipment disconnect is in the open, or off position.