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Nelson™ Heat Trace SMPS-1 In-Ground Sensor
Nelson™ Heat Trace SMPS-1 In-Ground Sensor is encased within a rugged enclosure and is intended to be embedded within the surface being heated, usually concrete or asphalt.
Nelson™ Heat Trace SMPS-1 In-Ground Sensor


Certifications and Compliances
cULus Listed: Ordinary Locations
Working Temperature
-40 °C to +70 °C (-40 °F to +160 °F)
Storage Temperature
-40 °C to +70 °C (-40 °F to +160 °F)
Relative Humidity
0 to 100%
Power Supply Voltage
24 Vac
Maximum Amperage
500 mA


  • The SMPS-1 is supplied with a protective field cover to simplify asphalt or concrete installations and comes with 9 m (30 ft) of wire for connection back to the SMMC-3 Control Panel
  • The low voltage SMPS-1 senses falling or drifting snow by melting it on the grid area of the sensor and then detecting the presence of moisture by measuring an electrical signal between the grid bars
  • The SMPS-1 also measures the temperature of the surface
  • This dual sensing technique allows the SMMC-3 to control the heating equipment (snow melting, de-icing cables, etc.) in the most efficient manner possible. This assures minimum energy costs while still providing reliable surface snow detection
  • The sensor enclosure is provided with a 1/2" NPT conduit connection
  • Connection wire may be extended up to 152.4 m (500 ft) with an appropriately rated 18-20 AWG 4-wire shielded cable