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. Questions can be sent to email@example.com. Answers are based on the 2014 NEC.
While trying to make my own labels on a large commercial project (basic office spaces) for panelboards to meet NEC requirements, I am starting to think that I will run out of real estate. There are two nominal voltage systems: 480/277 and 208/120 volts (V). Where does all of the labeling have to be? Can I include it with the panel schedule on the inside of the panelboard door? Is the same labeling required for switchboards?
In some cases, the NEC is very specific about marking locations, and in others, it is left up to the installer (to a degree). We should first take a look at the marking requirements that will always apply and a few that may apply in your installation. The installation you described is a commercial occupancy. We will group marking requirements for both panelboards and switchboards. The marking requirements must include an arc flash hazard warning, as required in 110.16. This marking must be on the outside of the equipment because it is required to be clearly visible to qualified people before examination. This is a field-applied hazard warning, and 110.21(B) will apply, requiring a permanent label that is not handwritten. As noted in your question, there is more than one nominal voltage system. Therefore, the identification of ungrounded conductors required in 210.5(C)(1) applies. In a commercial occupancy, this is typically achieved by posting the colors or means used for identification of ungrounded conductors at each panelboard or switchboard. There is no requirement to post this on the outside of the equipment or inside a door, but the posting must be permanent. This means that it cannot be on a removable panel schedule. This identification method may also be documented in a manner that is readily available, which works well in industry but not in the commercial, multitenant-type venue. A circuit directory is required per 408.4(A). The directory can be located on the face of the equipment at each switch or circuit breaker on a switchboard and on the face or inside of a panelboard. Where a panelboard or a switchboard is supplied by a feeder, 408.4(B) requires marking to indicate the device or equipment supplying the equipment.
This marking must be on the equipment, either on the face or inside the door. If your installation includes conductors that feed through a panelboard or switchboard, such as a feeder that supplies multiple panelboards with tap conductors, a permanent warning label, either on the front or inside the panelboard door, is required by 312.8(3).
Service equipment is required by 110.24 to be marked with available fault current. There are many other markings that will apply under specific circumstances that include, but are not limited to, 250.21(C) and 408.3(F).
It may seem difficult to get all of the marking requirements on a single label. However, for panelboards, a single label could easily include the required markings of 110.16, 210.5(C)(1) and 408.4(B) leaving the circuit directory [408.4(A)] to be placed inside the door. Switchboards will always be labeled on the face of the equipment with identification at each switch or circuit breaker.
Multiwire branch circuits
Why does the NEC continue to permit the use of multiwire branch circuits? We are now required to use a two- or three-pole circuit breaker anyway when we install a multiwire branch circuit. The benefit of using these circuits was that a single circuit that was part of a multiwire branch-circuit home run could be shut off and worked on without affecting a lot of the customer’s lighting or other loads. In our area, there was a recent fatality when an electrician working for a contractor doing lighting upgrades was killed on an open neutral from a multiwire branch circuit. Why not just delete all permission for these circuits?
There have been many electrocutions due to open neutrals on multiwire branch circuits, and that has been one of the driving forces behind revisions in the NEC for disconnection of these circuits. The general requirement that all multiwire branch circuits have a simultaneous means of disconnect is in 210.4(B). The requirement for circuit breakers supplying multiwire branch circuits does not always a necessitate common-trip two- or three-pole circuit breakers. These requirements are located in 240.15(B). Individual single-pole circuit breakers with an identified handle tie are permitted on systems rated 120/240V. A multiwire branch circuit supplied from a 480/277V system will require a common- trip two- or three-pole circuit breaker. All multiwire branch circuits now require a simultaneous means of disconnect.
Some day, we may see the NEC eliminate the use of multiwire branch circuits if substantial documentation is provided to the technical committees. There are multiple specific prohibitions of multiwire branch circuits in the NEC in 517.18(A), 517.19(A), 605.9(D) and 700.19.
We may see additional prohibitions in the next NEC cycle. The requirement for simultaneous disconnect will help prevent electricians from being injured or killed in open-neutral situations, provided the disconnect is opened and an electrically safe working condition is created. NFPA 70E addresses electrically safe working practices and provides the user with thresholds to determine justification of energized work. Where justified energized work is performed, a shock and arc flash risk assessment is required, along with all necessary personal protective equipment including, but not limited to, voltage-rated gloves.
Insulated conductors that are exposed to direct rays of the sun are required by 310.10(D) to be either listed for sunlight- resistance, listed and marked for sun exposure, or covered with tape or sleeving, listed, or listed and marked for the exposure. I have been installing service-entrance conductors that exit the service head and have never had an inspector ask if the conductors are listed for sunlight-resistance. I typically use SE, SER or PVC with THHW type insulation. Are these cables sunlight-resistant?
Type SE cable (includes SER) falls under the product category “Service Cable (TXKT).” Both the individual insulated conductors and the outer jacket or finish of Type SE are suitable for use where exposed to sun. Conductors with THHW insulation evaluated for sunlight-resistance are marked “SUNLIGHT RESISTANT,” “SUN. RES.” OR “SR.” See the UL White Book and the UL marking application guide for wire and cable.
Our local municipality adopted the 2008 NEC in 2011, and it looks like we are not going to move to a more current edition for some time. There are multiple revisions in both the 2011 and the 2014 editions of the Code that we would like to implement on projects, but the chief inspector simply states that they can only enforce the 2008, because that is the document that is currently adopted. Is there any way to convince the chief inspector that some aspects of the newer Codes can be implemented?
The NEC provides the authority having jurisdiction (AHJ) with a means to vary from the NEC currently adopted, provided an equivalent level of safety is achieved. Enforcement of the NEC is addressed in 90.4 and the second paragraph outlines how the AHJ can vary from specific requirements where necessary. The AHJ can provide you with special permission to permit an alternative method, which could be a revised requirement in a more current edition of the NEC. This requires that the AHJ is assured that equivalent objectives are achieved to establish and maintain an effective level of safety. The term “special permission” is defined in Article 100 as, “The written consent of the authority having jurisdiction.” I would suggest that you approach the chief inspector to discuss potential variations of the 2008 NEC based on the 2011 or 2014 edition and assure them that an equivalent or superior level of safety is established and maintained.
Where justified energized work is performed, a shock and arc flash risk assessment is required, along with all necessary personal protective equipment including, but not limited to, voltage-rated gloves.