Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at [email protected]. Answers are based on the 2023 NEC.

Dedicated equipment space

A township electrical inspector has requested we relocate a panelboard installed in a manufacturing plant. There are multiple runs of pneumatic tubes (air moving capsules) just below the structural ceiling, 9 feet above the top of the panelboard. Is that right?

No, the inspector is incorrect. The NEC requirement here is identified as “dedicated equipment space” located in Section 110.26(E)(1). This rule applies to all service equipment, switchboards, switchgear, panelboards and motor control centers. 

This requirement’s intent is twofold: to allow for future expansion from the electrical equipment and to protect it from damage due to condensation, leaks or other circumstances. The indoor requirement in 110.26(E)(1) mandates the dedicated space be equal to the width and depth of the equipment, extending from the floor to 6 feet above the equipment or to the structural ceiling, whichever is lower. As described, the pneumatic tubes are located beyond the minimum dedicated space and no potential for damage to the equipment below exists.

Clinical staff communications

Where receptacles and hard-wired connections to equipment are provided for a hospital paging system, are they required to be supplied from the essential system?

Yes, all clinical staff communication equipment is required to be supplied from the critical branch of the essential electrical system, as these communications are a function related to patient care. See 517.34(A) (list item (9)), which requires all task illumination, fixed equipment, receptacles and power circuits serving wireless phone and paging equipment be supplied from the critical branch of the essential electrical system. 

GFCIs in a commercial kitchen

In a commercial kitchen, if equipment identified in 210.8 is hardwired, is GFCI protection required?

Section 210.8(B) contains requirements for GFCI protection for personnel in places other than dwelling units. In kitchens, this requirement applies only to 125V–250V receptacles supplied by single-phase branch circuits rated 150V or less to ground, 50A or less, and all receptacles supplied by three-phase branch circuits rated 150V or less to ground, 100A or less.

With one possible exception, hardwired equipment in the commercial kitchen would not require GFCI protection. It is important to read and apply the requirements in Section 210.8(D) for GFCI protection of specific appliances. This is a general requirement that applies to all occupancies, and it mandates that dishwashers (see 210.8(D)(7)) rated 150V or less to ground and 60A or less, single- or 3-phase be provided with GFCI protection. 

Splicing EGCs

Hope you can settle a debate over splicing equipment grounding conductors (EGCs). Are green wire nuts required? Are the green tails with screws permitted in metal boxes?

No, green wire nuts are not required. General requirements for connecting grounding and bonding equipment are located in Section 250.8. This lists permitted methods for EGC connections that include listed pressure connectors, more commonly known as wire nuts. There is no color requirement. The green tails with machine screws are also permitted, provided they engage not less than two threads when placed in the hole from the box manufacturer or secured with a nut.

Energy storage system labeling

A line drawing on our project includes a note “label in accordance with NEC” for multiple energy storage system (ESS) disconnects. How do we apply an arc flash label?

Requirements for the installation of a disconnecting means in an ESS are located in Part II of Article 706. Section 706.15(C) requires that each disconnect be permanently labeled “energy storage system disconnect” and be field marked with the nominal ESS output voltage, the available fault current derived from the ESS, an arc flash label applied in accordance with acceptable industry practice and the date the calculation was performed. See informational note No. 1, which clarifies that NFPA 70E is an acceptable industry practice and provides two methods of arc flash labeling for an ESS. An incident energy analysis can be performed in accordance with NFPA 70E 130.5(G) or the arc flash PPE category method can be applied in accordance with 130.7(C)(15)(b).

GFP required in a floating building?

A historic, permanently moored ship is being renovated into a small restaurant. The engineer designed the 600A 208/120V feeder supplying the restaurant with ground fault protection (GFP). Is that a Code requirement? How is the GFP set?

The NEC considers the restaurant in your question as a floating building, and Part III of Article 555 applies. See Section 555.53, which requires the main overcurrent protective device supplying the floating building to have GFP not exceeding 100 mA.

Severe physical damage

Where does the NEC differentiate between physical damage and severe physical damage? As an apprentice instructor, I struggle to answer this question with any type of documentation to back it up. Can you provide some insight?

Over the course of many NEC revision cycles as a technical committee member, I witnessed attempts to define physical and severe physical damage. All were unsuccessful. It is difficult to capture each possible damage scenario in words. This situation reminds me of the saying, “Beauty is in the eye of the beholder.” 

The potential for physical and severe physical damage will vary dynamically with many factors to consider. One factor is the occupancy. The potential for damage will be much higher in a warehouse with forklifts versus a retirement home. When asked this question, I respond that when grocery shopping, you are capable of physical damage with the shopping cart. When you leave the market and get into your vehicle, you are capable of severe physical damage.

Alternate source required?

We are going to be installing a new feeder, panelboard and branch circuits in a home for an individual with fairly serious long-term health issues. Several branch circuits will supply medical equipment in the new space. Is an optional standby generator required?

The NEC does not contain such a requirement. The alternate source, in this case, if installed, is an optional standby system. The decision to install an alternate source for backup power should be made after an analysis is performed. See Informative Annex K in the NEC for guidance. The annex material suggests an analysis be performed to determine the need for backup power. Many factors will come into play including, but not limited to, the reliability and history of the local utility supply, patient mobility, their ability to use a portable generator and the ability to access others to assist. The annex material suggests that after all factors are analyzed, if a concern continues to exist, an alternate supply should be installed.

Trench backfill

Does the Code require pea gravel over raceways in a trench? One local inspector is requiring this type of fill before dirt is placed back in the trench. Other townships don’t require it and we are confused.

There is no blanket requirement for clean fill. Requirements for underground installations are in Section 300.5. The NEC requires granular or selected material, suitable running boards, sleeves or other approved means only where the existing backfill could damage the raceway or cable. If large rocks, paving materials, cinders, large or sharply angular substances, or corrosive material are in the backfill, then clean fill, such as pea gravel, would be required. See 300.5(F)

Emergency disconnect required?

Does the replacement of only frayed service conductors and the meter housing require an emergency disconnect be installed for a home?

No, see Section 230.85, which addresses emergency disconnect requirements for one- and two-family dwelling units. The general rule in 230.85(C) requires an emergency disconnect when service equipment is replaced. 

However, the exception following it allows replacement without an emergency disconnect where only meter enclosures, service entrance conductors and related raceways are replaced.

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