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 firstname.lastname@example.org. Answers are based on the 2017 NEC.
GFCI protection at the fair
We are contracted to install temporary power for the county fair. Our preliminary drawings were reviewed by the county electrical inspectors and we were informed that we did not need ground fault circuit interrupter (GFCI) protection for anything other than receptacle outlets that could be used by the general public and that we needed to remove those and provide a credit. Our design incorporates general GFCI requirements. Apparently, Article 525 modifies some of the requirements. Why would the NEC modify general GFCI requirements on metal structures installed outdoors where we know the public will gather? Wet ground, people in sandals— and sometimes barefoot—next to metal structures with temporary wiring strung all over is an accident to waiting to happen.
Article 525 provides requirements for the installation of portable wiring and equipment for carnivals, circuses, fairs and similar functions. This includes all wiring installed in or on any structure used in the event. Note that the scope of Article 525 clarifies that the wiring is considered to be “portable,” not “temporary.” I personally agree with your concerns about GFCI protection at a fair or any similar venue. We must always keep in mind that the requirements found in the NEC are minimum installation requirements. In essence, it is the least you can do. While providing additional GFCI protection may not be required, it is always permitted unless there is a specific prohibition in the Code.
The general requirements of 210.8 are modified in Section 525.23, which mandates that all non-locking type receptacles supplied at 125 volts (V), 15 amperes (A) and 20A used for disassembly and reassembly or accessible to the public, be GFCI protected. Equipment that is supplied at 125V, 15A and 20A that is accessible to the public must be GFCI-protected whether it is cord-and-plug connected or hardwired. Additionally, this requirement does not require (nor does it prohibit) GFCI protection of locking type receptacles that are not accessible from grade level used to facilitate quick disconnect and reconnect of equipment. This includes those supplied at 125V, 15A and 20A.
Section 525.23(C) prohibits GFCI protection of egress lighting. It is important to note that 535.23(D) requires that where GFCI protection is provided through the use of GFCI receptacles—and the branch circuits supplying receptacles use flexible cord (which is typical in these venues)—the GFCI protection shall be listed, labeled and identified for portable use. This provides open neutral protection. Section 90.1(B) states that the requirements in this Code are considered necessary for safety and compliance results in installation that this is essentially free from hazard. However, every NEC revision cycle, we see expansions of GFCI protection.
Transfer equipment documentation
How do I comply with the new requirements for documentation of transfer equipment in Article 700? What is the reasoning behind this new rule? Is this something that the engineer does, or is this a requirement for the electrical contractor? This seems to be limited to articles 700, 701 and 702. I do not see this requirement for healthcare facilities in Article 517. Am I correct in stating that this marking is not required for all transfer switches in a hospital?
The new requirements for field-marking of transfer equipment are found in 700.5(E), 701.5(D), 702.5 and 708.24(E). This level of documentation is necessary to allow electrical inspectors and installers/maintainers to determine short-circuit current ratings (SCCR) of transfer equipment (transfer switches) without first gathering information on upstream overcurrent protective devices (OCPDs) and then opening existing transfer equipment, which may be energized, to reference literature inside of existing transfer equipment to determine the applied SCCR. This new requirement mandates that the SCCR of the transfer equipment be field-marked on the exterior of the transfer equipment. The SCCR must be based on the specific OCPD type and settings used to protect the transfer equipment. This is an installation requirement and must be performed in the field, typically by the EC. The field-applied levels of SCCR will be different for all transfer switches based upon the type of OCPD and settings protecting the equipment.
For example, a single transfer switch may have a SCCR of 65,000A at 480/277V where protected by a 1,200A molded-case circuit breaker. The same transfer switch may have a SCCR of 200,000A at 480/277V where protected by a 1,200A current limiting fuse. This information is easily found on single line diagrams identifying the specific OCPD type and settings protecting the transfer equipment. All transfer equipment, in all venues (including healthcare facilities), must be documented in the same manner without regard to whether or not Article 700 applies. In all cases, the installation of a standby system will be identified as an emergency system (Article 700), a legally required standby system (Article 701), or an optional standby system (Article 702). All require documentation. Critical operations power systems (Article 708) also require SCCR documentation on transfer equipment.
I have always been under the impression that the NEC is a document limited to electrical installation requirements for safety purposes. Apparently, it has gone well beyond electrical installation requirements. During an electrical inspection for a small marina, I was instructed to install four signs to prevent people from swimming. I understand that a potential shock hazard may exist in some cases. Why is the NEC getting into the business of where people can swim and where they cannot?
The requirement for permanent safety signs to give notice of electrical shock hazard risks to all people using or swimming near a boat dock or a marina is new in the 2017 NEC and is located in Section 555.24. The signage is absolutely necessary to inform everyone of electrical shock drowning hazards because the general public does not understand the hazards that may be present in the water in these venues. Additionally, this signage is within the scope of the NEC as it is necessary for the practical safeguarding of people from hazards that arise from the use of electricity. See 90.1(A).
Article 555 for marinas, boat yards and commercial and noncommercial docking facilities saw many revisions in the 2017 cycle and more are on the way in the 2020 NEC revision. Where electrical currents exist in the water, there is a danger of electrical shock drowning. Low levels of current in the water may cause paralysis to those swimming, making them incapable of swimming away or staying above the surface of the water. While electrical equipment on a dock may introduce current into the water, it also is likely that a boat with faulty wiring connected to shore power will introduce current into the water. Section 555.24 requires these signs to be clearly visible from all approaches to a marina or boatyard facility.
That is why you were required in this case to install more than one sign. This requirement also mandates the sign comply with 110.21(B)(1), be sufficiently durable to withstand the environment and must also be labeled “warning—potential shock hazard—electrical currents may be present in the water.” This NEC requirement is safety driven; if we can keep people from swimming near a dock or a marina, there is no potential for electric shock drowning.
Sensitive electronic equipment
We were recently involved in a job that included some sensitive electronic equipment that fell under the scope of Article 647. This type of system was brand-new to me and required that I do a deep dive into associated NEC requirements. My question is related to 647.4(A). This requirement confuses me. In one sentence, it requires common trip two-pole circuit breakers and in another it requires a means to simultaneously disconnect ungrounded conductors. We could supply two single-pole circuit breakers with an identified handle tie and achieve simultaneous disconnection, but it would not be common trip. What is required?
The scope of Article 647 includes installation and wiring of separately derived systems operating at 120V line-to-line and 60V to ground for sensitive electronic equipment. The requirement that you reference in 647.4(A) addresses panelboards and overcurrent protection. Single-phase panelboards and distribution equipment with a higher voltage rating are permitted for these systems. The system (120V line-to-line, 60V to ground, single-phase) must be clearly marked on the panelboard. Common trip two-pole circuit breakers or combination two-pole fused disconnects identified for use at the system voltage must be provided for both ungrounded conductors in all feeders and branch circuits.
You are correct in that common trip circuit breakers do provide simultaneous disconnection of all ungrounded conductors, but two single-pole circuit breakers with a handle tie do not provide common trip. The last sentence is not necessary because the requirement is for a common-trip, two-pole circuit breaker or a combination two-pole fused disconnecting means that is identified for use at the system voltage. The two-pole fused disconnecting means provides simultaneous disconnection of all ungrounded conductors but not common trip, as only one fuse may open.