Guide specification

Section [__ __ __] · Frost heave prevention system, electric heat cable

Part 1 · General

1. 1.1Summary. Provide a subfloor heating system consisting of self-regulating heat cable installed in rigid conduit below the floor insulation, in the mud slab or aggregate base, with a processor-based controller that controls, monitors and alarms the system and provides troubleshooting information.
2. 1.2References. IEEE 515.1; NFPA 70 Articles 344, 426 and 427; manufacturer's instructions; local codes.
3. 1.3Submittals.
   1. A.Layout drawings showing conduit locations, spacing and dimensions.
   2. B.Electrical details: circuits, loads, inrush current and service required; control and monitoring wiring.
   3. C.Control panel schematic with terminal details.
   4. D.Product data for heat cable, connection kits, sensors and control panel components.
   5. E.Installation and startup instructions, detailed checkout form and replacement parts list with standard off-the-shelf part numbers.
4. 1.4Quality assurance. System provider shall have documented experience in the design, installation, startup and troubleshooting of frost heave prevention systems. Heat cable, controls and layout shall be furnished from one source.
5. 1.5Warranty. Control system: [2] years. Heat cable: [1] year.

Part 2 · Products

1. 2.1Manufacturer. Freezer Floor Systems, a division of Thermal Equipment Sales Co., Inc., Memphis, TN, (901) 452-4516 [or approved equal].
2. 2.2Heating cable.
   1. A.Low-temperature self-regulating cable, output per layout, with semiconductive polymer core that regulates output along its entire length.
   2. B.16 AWG nickel-plated or tinned copper bus wires; tinned copper braid ground conductor; fluoropolymer or thermoplastic elastomer overjacket for wet and corrosive locations.
   3. C.Maximum maintain temperature 150 °F (65 °C). Listed for the application.
   4. D.Maximum circuit lengths calculated for start-up at 32 °F.
   5. E.Silicone power connection and end seal kits at both ends of each cable. High-temperature silicone sealant at each cable entry to a junction box.
3. 2.3Conduit and boxes. Rigid conduit, ¾″ for loops under 100 ft and 1″ for loops over 100 ft. Weatherproof metal junction boxes, 4″ square minimum, screw cover, at each conduit end [provided by others].
4. 2.4Sensors. Type J thermocouple, lead length approximately one-half the floor width, stainless steel overbraid with fluoropolymer jacket, rated for direct submersion. Extension wire: Type J, 20 AWG, PVC/PVC, extension grade.
5. 2.5Control and monitoring panel.
   1. A.PLC with thermocouple input module, battery-backed memory, built-in flash backup of program and data, USB and Ethernet/Modbus ports.
   2. B.Color touchscreen operator interface rated NEMA 4X.
   3. C.Main disconnect with door interlock, lockable for lockout/tagout. Main lugs.
   4. D.Dedicated branch circuit breaker for each heating circuit, rated for cable inrush.
   5. E.30 mA ground-fault equipment protection for each heating circuit with auxiliary contact monitored by the PLC.
   6. F.Solid-state relay for each heating circuit, rated for inrush current.
   7. G.Far-end voltage sensing for each circuit, and an end-of-run relay for each cable run.
   8. H.Control transformer with fused primary and secondary; 24 VDC power supply.
   9. I.Combination red beacon and 98 dB horn with alarm silence push button. Horn re-sounds at [24 hours] until all faults are corrected.
   10. J.Dry alarm contacts [or 24 VDC output] for building management system. Remote 24 VDC input for peak-demand setback.
   11. K.Enclosure: NEMA [12] [3R] [4] [4X fiberglass] [4X stainless steel].
   12. L.Pre-wired and factory tested, with all field connections on labeled terminal strips.
6. 2.6Control functions. Operate each zone at a user-set temperature, minimum setpoint 32 °F, with setpoint and low alarm adjustable at the panel. Monitor and alarm: ground temperature and low temperature per zone; thermocouple break; ground fault per circuit; branch circuit fault; far-end voltage per circuit; continuity per run. Record fault history for each variable with location, count and time in alarm, with troubleshooting steps and replacement part numbers for the installation.

Part 3 · Execution

1. 3.1Installation. Install conduit, cable and sensors according to the layout drawings and the manufacturer's instructions. No splices inside conduit. Run sensor wiring separate from power wiring. Installer shall provide a complete, functional system in accordance with applicable codes. Ground and bond per Section 26 05 26.
2. 3.2Field testing. For each circuit, when cable and connections are complete:
   1. A.Visually inspect cable; replace damaged cable in full length.
   2. B.Inspect connections for correct assembly and moisture seals.
   3. C.Measure insulation resistance at the power connection with a 500 VDC megohmmeter. Replace any cable below 10 MΩ.
   4. D.Record end-of-circuit voltage. Verify end-of-run relay operation.
   5. E.Record current on each cable at startup and after 30 minutes.
   6. F.Verify all alarms. Record results on the checkout form and submit.
3. 3.3Closeout. After checkout, seal conduit entries with high-temperature silicone. Provide operation and maintenance instructions and instruct owner's personnel.