424.45 Installation of Cables Under Floor Coverings.
Code Change Summary: Previous requirements in 424.45 were relocated and a new code section was added to address floor heating cables installed under floor coverings.
For years, there have been rules in 424.99 that address floor heating “panels” or “heating panel sets” and proper installation methods under floor coverings. A lot of the time, instead of heating panels, heating “cables” are installed under floor coverings. Until now, the NEC® has mostly been silent on it other than a few rules in 424.44 which only applied if the cables were installed in concrete or poured masonry floors. How about under ceramic tile? What about wood flooring?
A new section was added in the 2017 NEC® that specifically addresses the installation of “cables” under floor coverings. Section 424.45 provides rules on proper cable identification, expansion and contraction fittings, splicing, anchoring and GFCI protection.
The previous code language found in 424.45 regarding inspections and tests was relocated to 424.46. This language requires cable installations to be made with due care to prevent damage to the cable assembly and also requires the cables to be inspected and approved before they are covered or concealed. This is one of the only places in the entire NEC® where inspections are required before covering. Most inspection requirements come from the applicable Building Code, Mechanical Code, Plumbing Code or Fuel/gas Code.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC® edition of NFPA 70.
2017 Code Language:
N 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. Ground-fault 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.