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.
Panic and fire exit hardware
The NEC rule for large equipment in 110.26(C)(3) requires panic hardware and doors that open in the direction of egress. During plan review for a proposed building in my town, I noticed the drawings show doors designed to open in the direction of egress, and there is a note requiring fire exit hardware but not panic hardware. Is there a difference? Does the NEC recognize fire exit hardware as panic hardware?
Yes, there is a difference. Listed fire exit hardware meets the requirements for listed panic hardware and is compliant with the NEC. The requirement in 110.26(C)(3) is for listed panic hardware, and the doors must open in the direction of egress. Panic hardware is an exit device designed for fast and easy egress in an emergency. Where electrical equipment rated 800 amperes (A) or more that contains overcurrent devices, switching devices, or control devices is installed and there are personnel doors intended for entrance and egress less than 25 feet from the working space, the doors are required to open in the direction of egress and be equipped with listed panic hardware. This provides electrical installers and maintainers the ability to quickly egress these rooms if there is an incident.
Panic hardware usually has a dogging feature, which allows the latches to be held retracted by using a hex key or other tool to create a push/pull function. This mechanical dogging to hold open the door latch is not permitted on listed fire exit hardware. Fire doors require positive latching to ensure the door stays closed in a fire situation. If the building designer requires a push/pull function for a fire door, electric latch retraction hardware is permitted to be installed as long as the latch projects automatically upon a fire alarm.
Nonsequential circuits, multiwire
In an existing commercial occupancy, there are multiple problems with shared neutrals. As we begin to identify home runs that can be reused, we are finding many shared neutrals that just don’t make sense. This seems like a serious safety issue for anyone that tried to perform maintenance here. In many locations, these home runs are multiwire branch circuits that do not have sequential circuiting, and it makes things difficult. For example, in one panelboard, we found four multiwire branch circuits, and none were sequential. One of them consisted of circuits 5 and 15. Can we reuse these home runs? Why was this permitted?
Section 210.4(B) requires all multiwire branch circuits to be provided with a means to simultaneously disconnect all of the ungrounded conductors at the branch circuit’s origin point. In this case, we are in a panelboard, so the circuit breakers or fuses in the panelboard must have a single switch or handle that simultaneously opens all of the ungrounded conductors. This requirement went into the NEC during the 2008 revision cycle. In the 2005 NEC, the only requirement for multiwire branch circuits was that they had to originate in the same panelboard or similar distribution equipment. That text permitted the installation you describe.
The occupancy you are working in was likely wired prior to local adoption of the 2008 NEC. It should be noted this requirement (simultaneous disconnect) does not mandate a common trip circuit breaker. Under certain conditions, an identified handle tie can be used with single-pole circuit breakers. The multiwire branch circuits (home runs) you describe can be reused if you install and they terminate in a means of simultaneous disconnect in the panelboard.
The requirement to simultaneously disconnect multiwire branch circuits is safety-driven and was adopted into the NEC due to many serious injuries and fatalities that occurred in open neutral scenarios. These hazards are further complicated when the circuits that make up the multiwire branch circuit are not sequential. In my experience, the renovation of existing commercial tenant spaces presents serious safety concerns due to the lack of simultaneous disconnect for multiwire branch circuits. Your question does not stipulate the systems and voltages. See Section 240.15(B) to determine requirements for multiwire branch circuits supplied from single-pole circuit breakers with identified handle ties.
We are installing a single-phase, 120-volt (V) piece of equipment that was manufactured in China in an outdoor environment. The wiring connection on the equipment side contains only a blue (neutral) and brown (line) wire. It does not have a white “neutral” wire. Does this make the equipment noncompliant if installed in the United States? Would an electrical inspector have a problem with that?
The questions answered in this column are based primarily on the NEC. You do not state what type of equipment you are installing nor if the equipment is listed. Original equipment manufacturers are not required to follow NEC rules for conductor identification inside of their equipment, so it may be a listed product. There is no general rule in the NEC that all equipment must be listed. However, there are listing requirements throughout the Code, including but not limited to luminaires.
Electrical installation safety is like a three-legged stool: the Code, product standards and inspections. Take away one of these legs and the installation’s safety is severely compromised. The electrical inspector will look for a listing on all equipment. A product standard likely exists in the United States for the equipment mentioned in your question. That said, you must ensure the equipment is listed. For one-of-a-kind equipment that is not listed, a field evaluation can be performed on-site by a Nationally Recognized Testing Laboratory to ensure safe operation.
GFCIs in Chapter 5
There is confusion on how ground-fault circuit interrupter (GFCI) requirements apply when we are in a special occupancy article in Chapter 5 of the NEC. When will the requirements of Section 210.8 still apply? If there are GFCI requirements in a Chapter 5 article, does that automatically override what is in 210.8? For example, in an agricultural building, is a 240V, 30A receptacle installed outdoors for an air compressor required to be GFCI-protected?
Section 90.3 provides prescriptive requirements on how the Code is arranged. Chapters 1 through 4 apply generally. This means these chapters apply in all locations and in every occupancy. Chapters 5, 6 and 7 apply to special occupancies, special equipment or other special conditions and may supplement or modify the requirements in chapters 1 through 7.
The key to this rule is that the Chapter 5 article in your question (547) may supplement or modify Section 210.8 requirements. Any requirements in 210.8 that are not prescriptively supplemented or modified in Article 547 shall apply. The only article-specific GFCI requirements for agricultural buildings are found in 547.5(G), which requires all 125V, single-phase, 15A and 20A receptacles installed in areas having an equipotential plane, outdoors, damp or wet locations, and dirt confinement areas for livestock, to be GFCI protected.
Note that 547.5(G) does not prescriptively modify 210.8(B), which requires the 240V, 30A receptacle in your question to be GFCI protected. Looking at another example of how GFCI requirements are addressed in Chapter 5, Section 555.19(B)(1) contains GFCI requirements for other than shore power in marinas, etc. This section provides prescriptive GFCI requirements that supplement the general requirements and ends with text that requires all other receptacle locations to be protected 210.8 requires. The reference to the general requirements in 210.8 increases usability but is not required as Code arrangement in 90.3 clarifies the general rules apply unless supplemented or modified.
Where flexible cords and cables are used as permitted in 400.10(A), list item number (6) permits connection of utilization equipment to facilitate frequent interchange. There are other uses of the words “frequent” and “infrequent” in the Code book. However, I cannot find a definition or example that would give me a clue as to what interval would be frequent. Where can I go for examples or a definition to show to the electrical inspector?
The NEC does not define general terms or common technical terms. There are many commonly used words in the NEC that may introduce a level of subjectivity to a requirement. In most cases, this is unavoidable when writing a rule. If we try to clarify the use of such terms, it could have a significantly negative impact on a rule’s application. The permitted use of flexible cords and flexible cables for connection of utilization equipment to facilitate frequent interchange in accordance with 400.10(A)(6) should be based on some documentation that interchange of the equipment in question will occur at a given interval.
For example, an automotive plant likely will undergo annual changes that impact equipment interchange as new models and designs are introduced. Retail venues may also see the need for frequent interchange based on displays that will be completely revised as seasons change and during different holidays. It is always a good idea to discuss such a rule with the authority having jurisdiction before moving forward.