Cable in Flood-Prone Areas, Damp Basements and More

Published On
Dec 15, 2021

Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at codefaqs@gmail.com. Answers are based on the 2020 NEC.

Type UF cable

Our area was hit very hard by recent storms. Many homeowners are in the process of having Type NM cable that was exposed to floodwater removed by contractors, who are replacing it with new Type NM cable. Many of these property owners are doing this for the second or third time. If we install Type UF cable for these homes and all of my splicing devices (wire nuts) are listed for wet locations and direct burial, with pigtails spliced to land on devices, will I need to replace the UF cable if they get flooded again?

The NEC does not specifically address water-damaged cable assemblies. Section 334.12(B) prohibits Type NM cable in wet locations, and 340.10 permits Type UF to be direct-buried and installed in wet locations. Typically, installers and inspectors will turn to the NEMA guide “Evaluating Water-Damaged Electrical Equipment,” which is free to download. The guide clearly states that it is not intended to override the recommendations of the specific equipment manufacturers. The emphasis is clearly on having qualified persons properly evaluate water-damaged equipment. The table in the NEMA guide clearly requires wire or cable listed for dry locations, such as Type NM, be replaced, and it permits wire or cable that is suitable for wet locations to be reconditioned, provided the ends of the wire or cable have not been exposed to water and the wire is not damaged.

Section 4.6 in the guide addresses water in contact with any metallic component (such as the conductor, metallic shield or armor). It provides more information on water-damaged wire, cable and cords. In my opinion (be sure to ask the manufacturer), the installation that you described would permit the reconditioning of Type UF cable if in the future it is exposed to water without any contaminants. Water cannot get inside of Type UF cable; it is a very robust cable assembly. Water will not get to the terminations with the splicing devices being listed for wet and direct-burial applications.

If water damage occurs in the future, it would be easy to address any damage to the bare equipment grounding conductors. Additionally, you would need to replace the pigtails and all devices and other exposed equipment, as based on the NEMA guide. In all cases, this reconditioning should be discussed with the authority having jurisdiction and any guidance from the product manufacturer.

Are all basements damp locations?

An inspector failed a small job in the basement of a dwelling unit, stating that type NM cable cannot be installed in a damp location. It was easy for us to change, but the basement was full of Type NM cable in the open ceiling, and the homeowner now thinks it is dangerous. While this basement had an active sump pump, which is what the inspector based his opinion on, we disagreed with the inspector. Are all dwelling unit basements damp locations?

No, all dwelling unit basements are not damp locations. In fact, some are bone dry and never see any degree of moisture. The fact that there was a sump pump that moved water does not make the basement a damp location. If we were to buy into that logic, we could not use Type NM cable in kitchens or bathrooms. The NEC defines a damp location as an area protected from weather and not subject to saturation with water or other liquids, but that is subject to moderate degrees of moisture. An informational note following this definition provides some examples of damp locations, including “some basements.”

The key to making this determination is the accumulation of “moderate degrees of moisture.” Damp locations accumulate moisture on surfaces, including cable assemblies and equipment. In an existing dwelling unit, installers and inspectors can easily identify a basement with serious water issues. The signs of water damage from the accumulation of moderate degrees of moisture will be obvious. In basements where damage from moderate degrees of moisture is evident, the basement is a damp location, and Type NM cable would not be permitted in accordance with 334.12(B)(4).

GFCI protection for appliances

We understand that 210.8(B) for GFCI protection in locations other than dwelling units impacts a lot of receptacles in a commercial kitchen. However, we recently failed an inspection and had to purchase and install a 30A, three-pole, GFCI circuit breaker for a hard-wired dishwasher at 208/120V. It wasn’t cheap. When did this GFCI requirement move from receptacles to include hard-wired equipment?

There are significant changes in the 2020 NEC with respect to GFCI protection of appliances. It was the result of what can only be described as a “turf war” between two committees with overlapping purview. The 2017 NEC Section 210.8(D) required GFCI protection of all outlets that supply dishwashers in dwelling units. Note that this requirement included receptacle-supplied and hard-wired dishwashers and was limited to dwelling units.

The dishwasher requirement in 210.8(D) was relocated in the 2020 NEC to Article 422 for appliances, specifically 422.5, which was significantly modified to include dishwashers and sump pumps. The parent text of 422.5 requires the appliances listed in 422.5(A) that are rated at 150V to ground or less and 60A or less, single-phase or three-phase, be provided with GFCI protection. This is a significant expansion for dishwashers from the 2017 to the 2020 NEC .

Section 422.5(B) provides five options to install listed and readily accessible GFCI protection. A new 210.8(D) is added in 2020 to provide guidance for GFCI protection of specific appliances, sending the Code user to 422.5.

Mandatory EV outlet?

I am a member of the building code committee in my town, and we are considering a local code requirement to mandate a receptacle outlet for charging an electric vehicle (EV) in every new home garage. Where is that requirement in the NEC , and what rating should we require?

The NEC does not mandate that a dwelling unit include provisions for charging an EV. See Part III in Article 625 for the installation of branch circuits and outlets for EV chargers. See 625.40, which mandates that each outlet installed for an EV charger be supplied by an individual branch circuit (as defined in Article 100) and shall supply no other outlets. Different EV chargers will have different ratings, so it would be difficult to mandate a single rating. Perhaps you could consider requiring a raceway such as 1-inch EMT be installed from the service equipment to the garage to facilitate the installation of an EV branch circuit and outlet in the future.

Two services?

Drawings were submitted to our municipality to add a second service for a small cabinetry manufacturer. There is an existing 480/277V, 400A service, and the owner requested a second 480/277V, 200A service on the opposite end of the building to expand operations. The township rejected the plans and told us to increase the size of the existing service. Is that correct?

The individual reviewing the plans is correct. The general rule in Section 230.2 is that a building be supplied by only one service. There are multiple exceptions to the general rule as outlined in 230.2(A) through (D). However, based on the information in your question, none of the requirements are applicable in your case: 230.2(A) applies only to special conditions, none of which apply here; 230.2(B) applies only to multiple occupancy and extremely large buildings; 230.2(C) applies only where capacity requirements exceed 2,000A; and 230.2(D) applies only where services are of different characteristics (voltage/system) and does not apply here, as the requested second service has the same characteristics. To expand, in this case, the owner needs to upgrade the existing service equipment.

About the Author

Jim Dollard

Code Columnist

Jim Dollard is the safety coordinator for IBEW Local 98 in Philadelphia. He is a member of the NEC Correlating Committee, NEC CMP-10, NEC CMP-13, NFPA 70E, NFPA 90A/B and the UL Electrical Council. He can be reached at codefaqs@gmail.com.

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