FIXED ELECTRIC SPACE HEATING EQUIPMENT 70-375

(c) Expansion Joints. Heating panels or heating panel sets shall not be installed where they bridge expansion joints unless provision is made for expansion and contraction. (d) Spacings. Spacings shall be maintained between heating panels or heating panel sets and metal embedded in the floor. Exception: Grounded metal-clad heating panels shall be permitted to be in contact with metal embedded in the floor. (e) Protection of Leads. Leads shall be protected where they leave the floor by rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or by other approved means. (f) Bushings or Fittings Required. Bushings or approved fittings shall be used where the leads emerge within the floor slabs. 424-99. Installation Under Floor Covering. (a) Identification. Heating panels or heating panel sets for installation under floor covering shall be identified as suitable for installation under floor covering. (b) Maximum Heated Area. Heating panels or panel sets, installed under floor covering, shall not exceed 15 watts per square foot (0.093 m²) of heated area. (c) Installation. Listed heating panels or panel sets, if installed under floor covering, shall be installed on floor surfaces that are smooth and flat in accordance with the manufacturer's instructions and shall also comply with the following: (1) Expansion Joints. Heating panels or heating panel sets shall not be installed where they bridge expansion joints unless protected from expansion and contraction. (2) Connection to Conductors. Heating panels and heating panel sets shall be connected to branch-circuit and supply wiring by wiring methods recognized in Chapter 3. (3) Anchoring. Heating panels and heating panel sets shall be firmly anchored to the floor using an adhesive or anchoring system identified for this use. (4) Coverings. After heating panels or heating panel sets are installed and inspected, they shall be permitted to be covered by a floor covering that has been identified by the manufacturer as being suitable for the installation. The covering shall be secured to the heating panel or heating panel sets with release-type adhesives or by means identified for this use. (5) Fault Protection. A device to open all ungrounded conductors supplying the heating panels or heating panel sets, provided by the manufacturer, shall function when a low or high resistance line-to-line, line to grounded conductor, or line to ground fault occurs, such as the result of a penetration of the element/element assembly. (FPN): An integral grounding shield may be required to provide this protection. 70-376 NATIONAL ELECTRICAL CODE