Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at [email protected]. Answers are based on the 2020 NEC.

Switchboard in a flood

A fitting on a large water pipe failed in a hotel, resulting in about 3 feet of water where the switchboard is located. We dried everything out, removed the circuit breakers that were in the water, cleaned it and turned it back on for temporary power. We were informed that it must be replaced. Are we permitted to reuse a switchboard that was in a flood? Can we reuse the molded-case circuit breakers after they dry out?

Yes, the switchboard can be reconditioned. Several new requirements apply to reconditioned equipment in the 2020 NEC that impact flooded electrical distribution equipment. Section 408.8(B) permits switchboards and switchgear—or sections of switchboards or switchgear—to be reconditioned. The parent text of 408.8 contains several additional requirements for reconditioning, including the use of design qualified parts verified under applicable standards, all work performed in accordance with any instructions provided by the manufacturer and if the equipment has been damaged by fire, products of combustion or water, there must be an evaluation of the switchboard by its manufacturer or a qualified testing laboratory prior to being returned to service.

Section 110.21(A)(2) requires that the reconditioned switchboard be marked with the name, trademark or other descriptive marking by which the organization responsible for reconditioning the equipment can be identified. Additionally, the switchboard must be marked as reconditioned with the date of the reconditioning and the original listing mark must be removed. This only requires the listing mark of the certifying body be obscured; it does not mandate or infer the removal of the nameplate or equipment label.

The circuit breakers cannot be reconditioned. See 240.88(A), which does not permit molded-case circuit breakers to be reconditioned.

Damp location receptacles

We have always considered areas that are protected from the weather to be damp but not wet locations. When installing receptacles under a porch, are they always in a damp location? Would a bubble cover be required for small porches on condo units?

The NEC does not include an easy button for the application of location types, so we need to look at them individually. A damp location is defined as an area that is protected from weather not subject to saturation with water or other liquids. Damp locations are subject to moderate degrees of moisture. Application of NEC rules for wet and damp locations requires that we consider each installation on a case-by-case basis.

Receptacles installed on a small porch (open to weather on at least one side) would be in a wet location because they would likely be subject to wind-driven rain. However, on larger porches, depending on the placement of the receptacle outlet, it would likely be a damp location. The installation of a receptacle on a small porch must include an enclosure that is weatherproof, whether or not the attachment plug cap is inserted. 

Dishwasher receptacle outlet

Does a cord-and-plug-connected dishwasher in a dwelling unit require that the receptacle be located in another cabinet? We have always installed one in the same space. Doing so would be taking a cord through a cabinet wall. Is that permitted?

A built-in dishwasher is permitted to be cord-and-plug-connected where all of the conditions listed in 422.16(B)(2) are met. A receptacle outlet for a built-in dishwasher is required to be located in the space adjacent to the space occupied by the dishwasher. A revision in the 2017 NEC eliminated the permission to install the receptacle outlet in the same space as the dishwasher. The prescriptive requirement in 422.16(B)(2)(5) permits the cord to pass through an opening, provided it is protected against damage by a bushing, grommet or other approved means. It is important to note that the requirement to provide GFCI protection of dishwashers in dwelling units was relocated from 210.8(D) to 422.5(A) in the 2020 NEC . This revision expanded the GFCI requirements to dishwashers in all venues.

Conductive pool shell?

I am installing a feeder-supplied panelboard in a new pool house with new branch circuits as part of an old pool restoration. I know we need to install perimeter bonding, but do we need to bond the pool shell? It is sand on the bottom with what looks like block and cement for the walls. No rebar can be found.

The pool in question will obviously be provided with a new vinyl liner to hold water. See 680.26(B)(1) for bonding requirements of conductive pool shells. This requirement clearly states that vinyl liners and fiberglass composite shells are considered to be nonconductive materials, and the bonding requirements of 680.26(B)(1) would not apply. Where a conductive pool shell is reconstructed, it must meet the requirements for bonding in this section.

Measuring switch height

When measuring for the permitted height of a disconnecting means, is the measurement from the concrete floor or the housekeeping pad on which the equipment is placed?

See sections 240.24(A) and 404.8(A) that include general requirements for switching device accessibility. The measurement must be taken from where a person would stand to operate the switch or circuit breaker. Both requirements mandate that the center of the grip of the operating handle when in its highest position is not more than 6 feet 7 inches above the floor or working platform.

Fixed electric space heaters

An inspection failed where we installed 10 AWG copper for a 6,000W electrical heater in an open sun room. The heater draws 25A. The inspector said it is a continuous load and needs to be 125% wire capacity. We have done hundreds of these installations with 10 AWG copper. What if we installed a one-hour timer?

The inspector is correct. See 424.4(B), Branch-Circuit Sizing, that requires branch circuit conductors for fixed electric space-heating equipment and any associated motors not be sized smaller than 125% of the load. Prior to the 2020 NEC , this requirement mandated that fixed electric space-heating equipment and motors be a continuous load. There is no prohibition to installing a one-hour timer provided it is rated for the load supplied. However, the requirements of 424.4(B) are clear. In all cases, branch circuits supplying fixed electric space heating equipment must be sized at a minimum of 125% of the load.

Performance test fuses?

How can a 2,000A fused disconnect be performance-tested as required by 240.67? Primary current injection testing will open the fuse, right?

Section 240.67 requires fuses rated 1,200A or higher be provided with a means of arc-energy reduction unless the fuse has a clearing time of 0.07 seconds or less at the available arcing current. Where documentation is provided that shows the fuse meets the prescribed clearing time at the available arcing current, no additional means of arc-energy reduction is required, and there is no need for performance-testing. Where the fuse cannot meet the performance-based clearing time, five permitted methods of arc-energy reduction are listed in 240.67(B).

The required performance testing will be performed on these methods where applicable. For example, consider list item (2), an energy-reducing maintenance switch with a local status indicator. When engaged (in the “on” position), this device will activate a switching means to open the circuit at a value below the current-limiting region of the fuse time current characteristic curve. Section 240.67(C) was added to ensure that the arc-energy reduction method chosen will function properly when installed. The associated informational note explains that some arc-energy-reduction protection systems cannot be tested using a test process of primary current injection. Without regard to the technology employed to meet these requirements, it is advisable to consult the manufacturer for instructions on how to successfully performance test the arc-reduction methods used.