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.
Requirements for maintenance
Why does the NEC contain requirements for maintenance? The inspector will not be around to ensure it happens.
This is getting a lot of discussion in the Code world. Maintenance requirements have been in the NEC for many cycles. The inclusion of additional prescriptive maintenance requirements in the NEC are long overdue. See 90.1(B), which explains NEC requirements are considered necessary for safety. Only with proper installation and maintenance is an installation essentially free from hazard.
References to NEC maintenance requirements are too numerous to list here, so I mention just a few. Requirements for working space around electrical equipment exists in the NEC to provide installers and maintenance personnel with the necessary space to work safely around energized equipment. These spaces must be maintained. There are dozens of exceptions based upon conditions of maintenance and supervision that ensure only qualified people service the equipment involved.
These exceptions are installation requirements that are prescriptively based in part on an understanding that proper maintenance will occur. NFPA 70B requires equipment such as low-voltage power circuit breakers to be maintained every three years. Manufacturers may provide a slightly longer time period, but the bottom line is these devices must be maintained.
In my opinion, maintenance requirements will continue to expand. While the inspector may be there only at the time of installation, the NEC’s maintenance requirements will drive other entities, such as state healthcare commissions, governmental bodies and the insurance industry, to monitor maintenance.
Trying to get around 250.122(B)
Understanding the NEC requires equipment grounding conductors (EGCs) to be increased in size when we increase the circuit conductors for voltage drop, is it permissible to add an in-line fuse to eliminate a very large EGC? The situation is lighting poles outdoors. These fixtures—per the cut sheet—require branch-circuit overcurrent protection at 20 amperes (A). Due to the distance from the building, we have to increase the circuit conductor size from 12 AWG to 8 AWG for voltage drop. If we land the 8 AWG ungrounded conductor on a 20A circuit breaker, the EGC must be sized at 8 AWG. Can we use circuit conductors that are 8 AWG protected at 40A with a 10 AWG EGC and then—at the pole—install in-line fuses rated at 20A? The in-line fuse will supply the 12 AWG THWN conductors we installed to supply the fixture heads. The conduits are already run. We must get two ungrounded conductors and one grounded conductor per conduit. We need to find a solution that will permit a reduced EGC to make this work. Is this permitted?
No. The lighting fixtures require branch-circuit overcurrent protection at 20A. The in-line fuse sized at 20A in your question is not branch-circuit overcurrent protection, but it is supplementary overcurrent protection.
There are multiple requirements in play. You are correct that an increase in the size of the ungrounded conductor for voltage drop or other reasons requires a proportionate increase in the size of a wire type EGC per 250.122(B). The required EGC at 20A is a 12 AWG, so increasing ungrounded conductors from 12 to 8 AWG will require an EGC sized at 8 AWG.
I understand your problem, but your proposed solution is not compliant. Section 240.10 permits supplementary overcurrent protection to be used for luminaires, appliances and other equipment or for internal circuits and equipment components, but it is not permitted be used as a substitute for the required branch-circuit overcurrent devices or in place of the required branch-circuit protection. The in-line fuse you are proposing would not be readily accessible as there would be a need for tools to access them and the exception to 240.24(A) would not apply.
The definition of “supplementary overcurrent protective device” clarifies that it is considered to be “limited protection” and is in addition to the protection provided by the branch circuit overcurrent protective device. Per your example, that protection would be at 40A, which is double the 20A protection required. Section 240.5(B)(2) does not apply for two reasons: the fixtures require protection at 20A, and the conductors supplied by the lighting pole are 12 AWG THWN conductors; they are not fixture wire.
Conduit body support
Are type TB conduit bodies required to be supported? We recently had a situation where four runs of EMT in a horizontal rack of 12 raceways had type TB conduit bodies installed. The raceways continued horizontally with four raceways from the back of the conduit bodies turning immediately on a separate rack to go elsewhere. To get a final inspection, we were required to add unistrut to support the type TB conduit bodies. We were told they require individual support. Is that right?
Requirements for support of enclosures covered in Article 314 are located in Section 314.23. Specific requirements for conduit body support are located in Section 314.23(E). The general rule permits this installation provided the conduit body does not exceed 100 cubic inches. However, the exception permits conduit bodies of any size to be supported by IMC, RMC, PVC, RTRC and EMT provided the trade size of the conduit body is not larger than the largest trade size of the conduit or tubing. As long as you were not using oversized conduit bodies, your installation was correct, and additional support was not required.
The NEC uses the term “habitable room” many times, but it is not defined in Article 100 or anywhere else. This leads to confusion in practical application, and decisions are at the inspector’s whim. This is further complicated by 210.70(A)(1), which leads the reader to believe kitchens and bathrooms are not habitable rooms. What is a habitable room?
The NEC does not presently define “habitable room.” We need to go to applicable building codes and use their definition for habitable rooms. NFPA 5000 defines a habitable room as: “a room in a residential occupancy used for living, sleeping, cooking, and eating but excluding bath, storage and service area, and corridors.”
This term applies only in a residential occupancy. The areas referenced are living, sleeping and cooking because these are areas where occupants spend extensive periods of time. Building codes do not consider bathrooms, storage areas and corridors to be habitable rooms. I agree the inclusion of “kitchens” in 210.70(A)(1) is confusing because rooms for cooking and eating are considered habitable rooms. The 2020 edition of the NEC will likely include a new definition to help clear up this confusion.
I recently came across equipment that looked like a switchboard, but it contained transformers and panelboards. As per the definition, a panelboard is installed in a cabinet or cutout box, correct? Is that a panelboard?
It seems the Article 100 definition of panelboard is not in line with the applicable product standards. The NEC definition states a panelboard is designed to be placed in a cabinet or cutout box placed in or against a wall, partition or other support, and is accessible from the front only. A review of the UL marking and application guide for panelboards provides insight into expanded use of panelboards and new terms.
Per the guide, panelboards are installed in cabinets, cutout boxes or within compartments of other equipment, such as deadfront switchboards. Some panelboards are shipped in an enclosure designed for their use. Based upon the equipment in which they are installed, permitted terms include the following marks: “enclosed panelboard” or “panelboard” with or without additional modifying phrases with an “electric cabinet box” and an “electric cabinet front.”
Illumination of service equipment
Section 110.26(D) requires lighting for service equipment that is installed indoors. Why is service equipment installed outdoors ignored? We recently responded to a trouble call, and the service equipment was on the outside of the building with no lighting at all. The Code should require lighting for outside service equipment.
As you point out, the requirements for illumination in 110.26(D) apply only to service-supplied equipment installed indoors. It must be understood that the requirements in this Code are minimum requirements only.
In many areas of the country, service equipment is installed on the outside of dwelling units, and the service disconnecting means is located in the meter housing or immediately adjacent. If this requirement was not limited to service equipment installed only indoors, all of these dwelling unit services would be required to have outdoor lighting installed.
It is not practical or feasible to include all service equipment in the requirements of 110.26(D). Service equipment installed indoors could very well be in the dark 24/7. Service equipment installed outdoors can easily be worked on during daylight hours in a safe manner. Where there is a need to work on or around service equipment outdoors, without sunlight, the contractor can easily supply temporary lighting for the safety of those maintaining the equipment.
Portable LED battery-supplied lighting units are readily available and inexpensive. Portable generators also can be used to supply lighting outdoors.