FIXED ELECTRIC SPACE HEATING EQUIPMENT 70-365

D. Marking of Heating Equipment 424-28. Nameplate. (a) Marking Required. Each unit of fixed electric space heating equipment shall be provided with a nameplate giving the identifying name and the normal rating in volts and watts, or in volts and amperes. Electric space heating equipment intended for use on alternating current only or direct current only shall be marked to so indicate. The marking of equipment consisting of motors over ¹/₈ horsepower and other loads shall specify the rating of the motor in volts, amperes, and frequency, and the heating load in volts and watts, or in volts and amperes. (b) Location. This nameplate shall be located so as to be visible or easily accessible after installation. 424-29. Marking of Heating Elements. All heating elements that are replaceable in the field and are a part of an electric heater shall be legibly marked with the ratings in volts and watts, or in volts and amperes. E. Electric Space Heating Cables 424-34. Heating Cable Construction. Heating cables shall be furnished complete with factory-assembled nonheating leads at least 7 feet (2.13 m) in length. 424-35. Marking of Heating Cables. Each unit shall be marked with the identifying name or identification symbol, catalog number, ratings in volts and watts, or in volts and amperes. Each unit length of heating cable shall have a permanent legible marking on each nonheating lead located within 3 inches (76 mm) of the terminal end. The lead wire shall have the following color identification to indicate the circuit voltage on which it is to be used: 120-volt nominal, yellow; 208-volt nominal, blue; 240-volt nominal, red; and 277-volt nominal, brown. 424-36. Clearances of Wiring in Ceilings. Wiring located above heated ceilings shall be spaced not less than 2 inches (50.8 mm) above the heated ceiling and shall be considered as operating at an ambient of 50°C (122°F). The ampacity of conductors shall be computed on the basis of the correction factors shown in the 0-2000 volt ampacity tables of Article 310. Exception: Wiring above heated ceilings and located above thermal insulation having a minimum thickness of 2 inches (50.8 mm) shall not require correction for temperature. 424-37. Location of Branch-Circuit and Feeder Wiring in Exterior Walls. Wiring methods shall comply with Article 300 and Section 310-10. 424-38. Area Restrictions. (a) Shall Not Extend Beyond the Room or Area. Heating cables shall not extend beyond the room or area in which they originate. (b) Uses Prohibited. Cables shall not be installed in closets, over walls or partitions that extend to the ceiling, or over cabinets whose clearance 70-366 NATIONAL ELECTRICAL CODE from the ceiling is less than the minimum horizontal dimension of the cabinet to the nearest cabinet edge that is open to the room or area. Exception: Isolated single runs of cable shall be permitted to pass over partitions where they are embedded. (c) In Closet Ceilings as Low Temperature Heat Sources to Control Relative Humidity. This provision shall not prevent the use of cable in closet ceilings as low temperature heat sources to control relative humidity, provided they are used only in those portions of the ceiling that are unobstructed to the floor by shelves or other permanent fixtures. 424-39. Clearance from Other Objects and Openings. Heating elements of cables shall be separated at least 8 inches (203 mm) from the edge of outlet boxes and junction boxes that are to be used for mounting surface lighting fixtures. A clearance of not less than 2 inches (50.8 mm) shall be provided from recessed fixtures and their trims, ventilating openings, and other such openings in room surfaces. Sufficient area shall be provided to assure that no heating cable will be covered by any surface-mounted units. 424-40. Splices. Embedded cables shall be spliced only where necessary and only by approved means, and in no case shall the length of the heating cable be altered. 424-41. Installation of Heating Cables on Dry Board, in Plaster, and on Concrete Ceilings. (a) Shall Not Be Installed in Walls. Cables shall not be installed in walls. Exception: Isolated single runs of cable shall be permitted to run down a vertical surface to reach a dropped ceiling. (b) Adjacent Runs. Adjacent runs of cable not exceeding 23/4 watts per foot (305 mm) shall be installed not less than 1½ inches (38 mm) on centers. (c) Surfaces to Be Applied. Heating cables shall be applied only to gypsum board, plaster lath, or other fire-resistant material. With metal lath or other electrically conductive surfaces, a coat of plaster shall be applied to completely separate the metal lath or conductive surface from the cable. (FPN): See also (f) below. (d) Splices. All heating cables, the splice between the heating cable and nonheating leads, and 3-inch (76-mm) minimum of the nonheating lead at the splice shall be embedded in plaster or dry board in the same manner as the heating cable. (e) Ceiling Surface. The entire ceiling surface shall have a finish of thermally noninsulating sand plaster having a nominal thickness of ½ inch (12.7 mm), or other noninsulating material identified as suitable for this use and applied according to specified thickness and directions. (f) Secured. Cables shall be secured at intervals not exceeding 16 inches (406 mm) by means of approved stapling, tape, plaster, nonmetallic spreaders, or other approved means. Staples or metal fasteners that straddle the cable shall not be used with metal lath or other electrically conductive surfaces.