Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at email@example.com. Answers are based on the 2020 NEC.
Distribution equipment for heat
We have serious supply chain issues on a job and must find a solution for the owner before heat is needed in the building. We installed a 1,200A feeder (4 x 350 kcmil cu) to supply distribution equipment for heat. The equipment has been back-ordered for over a year. Can we temporarily supply an 800A MCCB in a panelboard with three parallel legs and a 200A circuit breaker enclosure with the fourth parallel leg? The ampacity is there and it is only temporary.
No. That would violate several NEC requirements and create significant safety concerns. The practical/feasible solution here would be to apply feeder tap rules in 240.21(B) to supply the 200A and 800A devices. It is important to note that the 200A and 800A devices must be supplied by all four parallel legs of the 1,200A parallel feeder with the tap conductors sized as required. See 310.10(G)(1), which permits a parallel feeder provided conductors 1/0 AWG and larger are electrically joined at both ends.
Our service-oriented company does maintenance in multiple venues in our area. We are well-versed in OSHA requirements and understand that construction-related activities using power from permanent receptacles still requires GFCI protection. We were recently audited and told that the small portable GFCI devices we issued must be replaced with NEC-compliant devices. What are they?
See 590.6(A)(2), which contains GFCI requirements for personnel when using receptacle outlets that are permanently installed. GFCI protection is required for all 125V, single-phase, 15A, 20A and 30A receptacle outlets installed or existing as part of the permanent wiring of the building or structure and used for temporary electric power. This section specifically permits listed cord sets or devices incorporating listed GFCI protection for personnel identified for portable use.
It is likely the devices you are using are listed but are not “identified for portable use.” There is a big difference. GFCI devices that are “identified for portable use” provide open neutral protection. GFCI devices will open on ground fault only when the electronics of the device are active. If the permanent receptacle an employee plugs into has an open neutral, the electronics of the portable GFCI device are disabled and ground fault current could flow without any protection. A GFCI device that is “identified for portable use” will open the grounded and ungrounded conductors if the connection to the hot or neutral is lost, thereby protecting the employee.
We are renovating an unused floor in a small hospital that will be used as a training center for nurses. The drawings show patient care rooms, but do not have branch circuits in compliance with Article 517. When we sent a request for information, the response was that these rooms are for training purposes and would only be used for actual patients in an emergency, therefore general wiring was sufficient. Do these rooms require hospital-grade wiring?
As described in your question, this venue is a healthcare facility. While the primary use of the rooms described may be for training nurses and other medical staff, the owner notified you that the rooms are intended to be used as patient care rooms if the need arises. All Article 517 requirements apply. If this were a separate venue used only for training, Article 517’s requirements would not apply.
Meter socket enclosures
We always use listed connectors for Type SE cable on the bottom side of our meter enclosures. They are not watertight. A service lateral in PVC conduit also enters the bottom of the meter enclosure. A newer electrical inspector failed one of our services because he stated that all SE connectors outdoors need to be rated for a wet location. When we asked why, he told us to see Article 338. We found no such requirement. I have checked the local utility regulations and they specify a wet location connector when you enter the top of the enclosure. There is no mention of connectors rated for wet locations when it is an underground installation. Any help would be greatly appreciated.
The NEC permits the installation described in your email. Article 338 does not address requirements for cable connectors; in fact the word “connector” does not exist in the article. Requirements for meter socket enclosures are located in Article 312 (see 312.2). The general rule for installations in damp or wet locations mandates that surface-type meter socket enclosures be installed to prevent moisture or water from entering and accumulating, and there must be at least ¼-inch of airspace between the enclosure and the wall or other supporting surface. Meter socket enclosures installed in wet locations must be weatherproof. The answer to your question is found in the last sentence of 312.2. Where installed in a wet location, raceways or cables entering above the level of uninsulated live parts must use fittings listed for wet locations. In this case, the connector is not installed above the level of uninsulated live parts.
We have an ongoing disagreement on a job with respect to workspace clearance requirements. We agree that panelboards, switchboards, etc., need the required space, but what about a junction or pull box? The problem is that the very first sentence in 110.26 requires the minimum distances. This section confuses me.
The requirements of Section 110.26 are clear and unambiguous. The section title is carefully worded as “Spaces About Electrical Equipment.” Note that the term “working space” is not included in the parent text of this section. The parent text requires access and working space be provided and maintained about all electrical equipment to permit ready and safe operation and maintenance of such equipment. This general requirement does not come with specific distances based on voltage, etc., because it is simply a general requirement.
Specific requirements for working space with minimum distances are addressed in 110.26(A), Working Space, which prescriptively limits this rule to “equipment operating at 1,000 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized.” The key here is to understand that not all electrical equipment is likely to require examination, adjustment, servicing or maintenance while energized. The NEC does not come with an easy button; this decision must be made by the designer, installer and the AHJ. For example, you mention a junction or pull box. In general, they are not likely to require any task while energized, and the specific dimensions will not apply. Could someone design an application where a junction or pull box would come with a regular task that required work while energized? It’s possible, but unlikely, and in that case the prescriptive distances would apply.
Generator conductor ampacity
I have always sized the conductors from the circuit breaker on a generator into the building with an ampacity equal to or higher than 115% of the generator output. Another contractor told me that there was no reason for that, is that correct?
Yes. The requirement in question is 445.13, Ampacity of Conductors. See 445.13(A), which requires the ampacity of the conductors from the generator output terminals to the first overcurrent protective device (OCPD) to be sized at not less than 115% of the nameplate current rating of the generator. The conductors referenced in this requirement have no overcurrent protection because they originate in the generator stator and terminate on the line side of an OCPD. Where a generator is equipped with an OCPD (typically a molded-case circuit breaker), the conductors on the load side of the circuit breaker are a feeder or branch circuit, and they are not subject to the requirement in 445.13(A).