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. Questions can be sent to firstname.lastname@example.org. Answers are based on the 2014 NEC.
Abandoned cable in ceiling
Does old Category 5 communications cable and coaxial cable need to be removed from a lay-in type ceiling? We are upgrading the lighting in a large commercial occupancy, and the ceilings are full of unused, abandoned cable that has been made obsolete with advancements in technology, such as fiber optic cable.
The situation that you have described would require the cables to be removed. All accessible portions of abandoned cable must be removed. Cables that are identified for future use may be tagged and left in the ceiling. Where newer technology mandates an upgraded cable type, tagging the old cable for future use is not an option because there would be no feasible use for the old cabling. The advancements in technology will continue, and the older cables must be removed as systems are upgraded with new cable. The requirements for removal of these cables are in 800.25 for communications cable and 820.25 for cable TV.
Hot tubs and equipotential bonding
We are preparing a bid for a condominium with 30 individual units. An indoor hot tub will be installed in each of the units. Multiple outdoor hot tubs will be installed in a common area on the ground floor. All of the hot tubs are owner-supplied and are only identified as a packaged unit that will only need to be set in place with electrical and plumbing connections. Do we need to install an equipotential bonding grid for the hot tubs?
The general rule for an indoor hot tub in Section 680.43 requires that the installation be installed in accordance with Parts I and II of Article 680, which would require equipotential bonding. However, 680.43 Exception No. 2 waives the equipotential bonding requirements in 680.26(B)(2), provided that the hot tub is a listed, self-contained unit and is installed above a finished floor.
The requirements for the outdoor hot tub are similar. The general rule for an outdoor hot tub in Section 680.42 also requires compliance with Parts I and II of Article 680. However, 680.42(B) permits installation without the equipotential bonding in 680.26(B)(2) provided that the hot tub meets the following:
• Listed as a self-contained unit for above-ground use
• Not identified for only indoor use
• Installed on or above grade and in accordance with manufacturer’s instructions
• Installed with the top rim of the hot tub at least 28 inches above all perimeter surfaces within 30 inches measured horizontally of the unit; nonconductive steps cannot be used to reduce or increase the rim height measurement.
It would be prudent to request information from the owner on both the indoor and outdoor hot tubs to ensure that they comply with the permissive rules for excluding the equipotential bonding.
Listing of junction boxes
I had a junction box custom-made to install a large parallel feeder in a large shopping mall’s existing electrical room. The box was necessary to get the feeders out of the switchboard; there was no room to install 90-degree bends. The conduit and conductors are installed. An inspector went into the junction box and identified the lack of a listing label on the box as a violation. There is a label from the manufacturer but no listing label. He told me that everything for the feeder—the EMT, cable and box—must be listed. I have been struggling to find anything in the NEC that would require listing for the junction box. Are custom-made metal junction boxes required to be listed?
The NEC contains no general requirement that junction boxes be listed. Based on the limited information in your question, the box in this case does not need to be listed, but it must comply with other NEC requirements. There are, however, some cases that require a box to be listed. The inspector should have provided you with a section in the NEC if he or she felt there was a violation.
Part III of Article 314 contains requirements for the construction of junction boxes. The following is required for the custom-made box in your situation:
• Be corrosion-resistant
• Be made of a minimum metal thickness of 0.053 inch (17 gauge)
• Contain provisions for grounding
• Have the cover made from the same material
• Be marked with the manufacturer’s name or trademark
There are several requirements in the NEC that would mandate a listed junction box. They include, but are not limited to, 314.15 junction boxes in wet locations, 314.27(B) for floor boxes, and 314.27(C) for ceiling-suspended paddle fans.
Guest rooms with cooking provisions
During plan review for a 60-room hotel, we were informed that we needed to install panelboards and small appliance branch circuits in all of the efficiency rooms because they contained cooktops in the kitchenette. Why would we be required to do that when all of the other hotel rooms’ branch circuits can be supplied from a panelboard in an electric closet down the hall?
The results of the plan review are correct. Multiple NEC requirements apply to guest rooms and guest suites with permanent provisions for cooking. However, these requirements do not apply in standard rooms. The reason is that rooms with kitchens provided with permanent provisions for cooking are commonly used for more than a typical stay of a few days or a week. In many cases, hotel chains refer to rooms with permanent provisions for cooking as “extended-stay” rooms. It is also common to have provisions for doing laundry in this type of room. This means that the room will be used in a manner very similar to a dwelling unit. For that reason, the NEC mandates the same safety-driven installation requirements as a dwelling unit. The plan review noted that the following NEC requirements are specific to guest rooms and guest suites with permanent provisions for cooking:
• 210.18 requires branch circuits to be installed to meet the rules for dwelling units.
• 240.24(B) requires the occupant to have ready access to overcurrent devices. 240.24(B)(2) provides an exception for standard guest rooms and guest suites but not those with permanent provisions for cooking.
Firestopping for junction boxes
We are using listed, fire-rated intumescent pads that go on the inside of junction boxes to maintain the fire rating on walls between dwelling units. The building code requirements address the issue of openings on opposite sides of the wall where they are spaced at 24 inches or less. If we maintain a spacing of more than 24 inches, are we still required to maintain the fire rating? Where we have boxes on the opposite sides of the wall within 24 inches and one side is fireproofed, do we need to fireproof the other side?
Section 300.21 requires that the installer firestop all penetrations into or through fire-resistant or fire-rated walls, partitions, floors or ceilings. Anytime a penetration is made in a fire-rated wall, such as for a receptacle outlet or switch, the NEC requires firestopping. Any through-the-wall, floor or ceiling penetrations for conduits or cable assemblies, etc., must also be firestopped on both sides of the wall. The informational note in 300.21 directs the NEC user to review the listing installation restrictions necessary to maintain the fire rating of the wall, floor or ceiling. It is imperative that you get the right product for your specific application and install the material in accordance with the manufacturer’s instructions.
Where boxes are installed on the opposite sides of the wall within 24 inches, both sides are required to be fireproofed. Prior to the 2011 NEC, and the revision of 300.21 to specifically address “penetrations into or through,” this was not clear to the NEC users. However, both sides still needed to be fireproofed because of the testing and listing requirements of the firestopping materials used.