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SUGGESTED SPECIFICATION FOR DESIGN AND INSTALLATION OF M.I. ELECTRIC HEAT TRACING SYSTEMS FOR SNOW AND ICE MELTING IN RAMPS, SLABS, SIDEWALKS, DRIVEWAYS, ETC. PART 1 - GENERAL  1.1 Scope This specification covers the general requirements for the design and installation of a snow and ice melting system.The electrical contractor shall supply and install a complete snow and ice melting system which shall consist of the following: 1.1.1 Electric heating cables. 1.1.2 Temperature controllers and auxiliary sensors. 1.1.3 Accessory materials such as contactors, prepunched strapping , junction boxes, etc. 1.1.4 Heating panel and feeders 1.2 Reference The extent of the snow and ice melting system is as shown on specification sheets and architectural drawings. 1.3 Codes and Standards The entire design and installation of the system shall comply with the Electrical Code (current edition) and the requirements of the "Authority Having Jurisdiction". All heaters shall be CSA approved and/or UL listed for this application. The manufacturer shall have a minimum of 25 years experience manufacturing the heating cables herein specified. Self-regulating cables are not acceptable for this application. PART 2 - PRODUCTS / MATERIALS 2.1 Heating Cable Type M.I. heating cable shall be manufactured by Tyco Thermal Controls Pyrotenax (Tel: 800-234-6501, Fax: 800-410-8677), magnesium oxide insulated, with copper or resistance alloy conductor and a seamless copper sheath. The heating cable shall be constructed in such a manner that no combustible materials are allowed between the resistance alloy conductor and outer metal sheath. All heater core materials shall be inorganic and will not deteriorate with age. The cable shall be jacketed with high density polyethylene (HDPE) to further resist corrosion. Each heater shall be factory-fabricated to the length required and shall not be altered on site. The heated section shall be joined to a PVC jacketed copper sheath cold lead section by a factory-made joint. Cold lead shall be seven feet long unless otherwise specified. To ensure maximum snow melting rate, heat output shall not decrease as the temperature of the slab increases. Heating cables that modulate their thermal output and cannot be checked for circuit integrity, or are characterized by high inrush currents at start-up, are not acceptable. 2.1.5 Heating cables will be designed for operation on a standard supply voltage such as 120, 208, 240, 277, 347, 480, or 600V single or 3 phase as appropriate. 2.2 Control All heating circuits shall be controlled by one of the following methods:1 an automatic snow/ice sensor (preferred) which detects precipitation occurring at temperatures below 38 ° F (4 ° C).a high limit slab sensing thermostat. 2.2.2 Where the rating of the controller would be exceeded, it shall be used in conjunction with a relay or contactor. PART 3 - EXECUTION 3.1 Installation The current revision of the manufacturer's Installation Recommendation for Heating Cable in Heat Conducting Concrete Slabs, Engineering Information Sheet #H1; in Road Type Asphalt, Engineering Information Sheet #H2; or Beneath Precast Pavers, Engineering Information Sheet #H3 as appropriate shall be considered part of this specification. Cable sheaths shall not touch or cross one another nor shall the heating portion of cables cross expansion joints. Special procedures are required for crossing control and construction joints. 3.1.3 Heating cables are laid out at the specified spacing. Spacing should not be greater than 9 inches to ensure reasonably uniform distribution of heat. 3.1.4 All junction boxes shall be located in accessible areas. Junction boxes shall not be located in the heated slab, but shall be located above grade level. Covers shall be kept on boxes at all times when not working therein. 3.1.5 All terminations shall be protected from the weather and from physical damage and bonded to the system ground. 3.1.6 Any field alternations or deviations shall proceed only after authorization has been issued by engineer. All changes shall be accurately recorded by the contractor and shall be turned over to the engineer upon completion of that phase of the work. 3.2 Testing 3.2.1 Field testing of insulation resistance and continuity of the units shall be carried out with a 500 volt insulation tester and recorded by the Electrical Contractor. Testing shall be done when received on the job site, during installation, and after installation, by the Electrical Contractor. 3.2.2 Insulation resistance shall be consistently not less than 5 megohms. 3.2.3 A complete system test shall be performed to verify system operation. 3.2.4 Copies of all such testing shall be delivered to the Engineer. |
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