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.
For larger dwelling-unit kitchens, the rules for ground fault circuit interrupter (GFCI) receptacles on countertops need to be revised. In my opinion, it makes sense to require GFCI protection within a given perimeter of where water exists, such as a sink. In some cases, we have to install GFCIs that may be 25 or 30 feet from the sink. Can you explain why every receptacle on the kitchen countertop needs to be GFCI-protected?
Article 100 defines a kitchen as “an area with a sink and permanent provisions for food preparation and cooking.” All kitchen countertops are considered as an area where food preparation may take place.
We do not need a sink to introduce conductive surfaces, water or other liquids, to kitchen countertops. Food preparation includes water and other liquids. Kitchen countertops will also be populated with appliances such as coffeemakers, toasters and slow cookers. In many cases, kitchens have tiled floors, built-in metal appliances and other grounded objects on and around the countertops.
Plus, we cannot predict how the homeowner will use the countertop spaces. For example, a homeowner may use portable power strips and extension cords on the countertop to supply even more appliances.
GFCI requirements for kitchen countertops are well substantiated and have undoubtedly saved many lives. Protection of all receptacle outlets on kitchen countertops is practical and feasible.
We have a question regarding Code for lighting in residential shower enclosures. We are working on multiple high-rise residential units in various regions throughout the state. In some cases, dead-front/nonconductive trims have been requested, but not in all. Does the NEC require recessed fixtures to be “dead front” in the shower, or is this coming from local municipalities?
The term “dead front” does not apply to luminaires. NEC requirements for luminaires in bathtub and shower areas are located in Section 410.10(D). This requirement prohibits cord-connected, chain-, cable- or cord-suspended luminaires, lighting track, pendants or ceiling-suspended paddle fans within the space (as described) of the bathtub or shower stall threshold. Luminaires that are located within the dimensions provided for the bathtub or shower must be marked for damp locations or marked for wet locations where they are subject to shower spray. The NEC does not address conductive or nonconductive trims for permitted luminaires. Those requirements exist in applicable product standards.
Working space, transformers
Is a dry-type, 15-kilovolt-ampere (kVA) transformer subject to workspace clearance requirements in the NEC? We get conflicting signals from inspectors and engineers. Recently, an inspector red-tagged us for a small transformer in a ceiling. When installing dry-type transformers, we try to apply workspace clearance requirements in 110.26, but in some cases, it is impossible. We do not do anything hot inside of a transformer, so why would those rules apply?
The requirements for working space in 110.26(A) exist solely to provide installers and maintainers with the minimum space necessary to perform justified energized work. These rules apply to all equipment operating at 1,000 volts (V), nominal, or less to ground and likely to require examination, adjustment, servicing or maintenance while energized.
The key to applying working space requirements is to determine if the equipment in question is likely to require examination, adjustment, servicing or maintenance while energized. This determination is relatively easy for most equipment. For example, panelboards and switchboards may require justified energized work when voltage testing or troubleshooting is performed, and the working space requirements always apply.
The determination is not as easy with transformers. Not all transformers will be likely to require examination, adjustment, servicing or maintenance while energized. Any transformer that is subject to regular maintenance, such as infrared thermography, requires working space clearances in accordance with Section 110.26. In some venues, transformers will never be maintained or opened for any reason unless they fail and are ultimately replaced. I have seen instances in which the authority having jurisdiction mandated workspace clearance requirements to be applied to all transformers. However, the only activity likely to be performed on an energized transformer is maintenance. Unfortunately, there are very few venues in which such maintenance is performed.
The 2017 NEC includes language that, until Jan. 1, 2020, allows me to use motion-sensor-type switches for lighting that puts current on grounding conductors. I am confused. I thought we changed that some time ago when the requirement for bringing the neutral to each switch location went in the Code.
In the 2011 NEC revision cycle, new requirements were added in Section 404.2(C) for switches controlling lighting loads. This huge change affected all switches controlling lighting loads that are supplied by general-purpose branch circuits. This required the grounded circuit conductor (neutral) for the controlled lighting circuit to be provided at the switch location. In the 2014 NEC revision cycle, these requirements were modified slightly for clarity.
During the 2017 revision cycle, the technical committee realized, while they had a requirement to bring the grounded circuit conductor to the switch location, nothing required it to be used. New Section 404.22 contains requirements for the construction of electronic lighting control switches. These switches must be listed and cannot introduce current on the equipment grounding conductor (EGC) during normal operation.
The last sentence clarifies that the requirement to not introduce current on the EGC takes effect on Jan. 1, 2020. It is not uncommon to use a delayed implementation date in the NEC. It allows manufacturers time to ramp up construction of electronic lighting control switches that meet this requirement.
Section 404.22 contains an exception that will continue to permit electronic lighting control switches that introduce current onto EGCs for replacement or retrofit of switches that were installed prior to local adoption of 404.2(C). It is important to note that 404.2(C) Exception No. 2 will limit the number of electronic lighting control switches on branch circuits to a total of five and the total number connected to any feeder on the load side of the system main bonding jumper cannot exceed 25. This will have a significant effect on commercial installations where each office may contain electronic lighting control switches.
What happened to the table in 310.15 for conductor sizes in single-phase dwelling services? Is this a mistake, or was it intentional? We have used that table for many years, and the reductions in size help us keep installation costs down.
Table 310.15(B)(7) was deleted in the 2014 revision cycle. This section provides permissive requirements for single-family dwellings and individual dwelling units of two-family and multi-family dwellings for sizing of service or feeder conductors. It is important to note that application of this requirement to a feeder applies only where the feeder conductors supply the entire load. While this table was deleted, the permission to reduce the size of the conductors remains, allowing an ampacity not less than 83 percent of the service or feeder rating. The table was deleted because of concern that installers went only to this table and did not consider other correction or adjustment factors that may have been applicable to the installation.
During the 2017 revision cycle, this table was reinserted into Annex D, Section D7. Additional revisions in the 2017 NEC expand these permissive requirements from application to only single-phase, 120/240V systems, to also include single-phase feeder conductors that consist of two ungrounded conductors and the neutral conductor from a 208Y/120V system. This will now permit feeders in apartment houses and condominiums to take advantage of this rule where there are 208Y/120V systems. It is important to note that the permission to reduce the size of the grounded conductor does not apply to single-phase feeders from 208Y/120V systems.
Where type MC cable is transitioned to conduit with a fitting that is listed for that purpose, does it need to be exposed? In the mechanical areas of the job we are working, everything must be in conduit. Where we turned down into a wall, we transition to type MC cable. Does 300.15 apply? Should we use a junction box?
Section 300.15 does apply and requires in general that a box or conduit body be installed at each conductor splice point, outlet point, switch point, junction point, termination point or pull point.
Twelve first-level subdivisions permit other methods. Section 300.15(F) permits a fitting to be used in lieu of a box or conduit body where the conductors are not spliced or terminated within the fitting. The fitting is required to be accessible after installation. Installing a listed transition fitting between Type MC cable and conduit would not be permitted inside of the wall because it would be rendered inaccessible. You could use a junction box, but that would not be required.
The listed transition fitting also could be used, provided that it was located outside of the wall and accessible.