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424.45 Installation of Cables Under Floor Coverings

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Change Summary

  • New requirements were added for the installation of heating cables installed under floor coverings.
NEC® Text

424.45 Installation of Cables Under Floor Coverings.
(A) Identification. Heating cables for installation under floor covering shall be identified as suitable for installation under floor covering.
(B) Expansion Joints. Heating cables shall not be installed where they bridge expansion joints unless provided with expansion and contraction fittings applicable to the manufacture of the cable.
(C) Connection to Conductors. Heating cables shall be connected to branch-circuit and supply wiring by wiring methods described in the installation instructions or as recognized in Chapter 3.
(D) Anchoring. Heating cables shall be positioned or secured in place under the floor covering, per the manufacturer’s instructions.
(E) Ground-Fault Circuit-Interrupter Protection. Groundfault circuit-interrupter protection for personnel shall be provided.
(F) Grounding Braid or Sheath. Grounding means, such as copper braid, metal sheath, or other approved means, shall be provided as part of the heated length.

Copyright© 2016 National Fire Protection Association
(See NEC for complete text)

Expert Analysis

A new 424.45 with prescriptive language for the installation of heating cables under floor coverings was added. This practice is not new to the electrical industry, but installation requirements for these under flooring heating cables is new for Article 424. These types of heating cables are required to be GFCI protected.

Heating panels, as well as heating cables, are being installed under floor coverings such as ceramic tile in bathroom and showers, under laminate flooring, and sometimes even under carpet. It is critical that these installations comply with the listing, product standard, and the manufacturer’s instructions. Before the 2017 NEC, Part V of Article 424, which deals with electric space-heating cables, did not specifically mention under floor coverings for heating cables. According to some users of the Code, this left it unclear whether or not heating cables installed under a floor covering was permitted. To clear up this confusion and to make it clear that this type of installation is permitted by the NEC, the new text of 424.45 has been added, which is similar to the text of 424.99 for electric radiant heating panels and heating panel sets.

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