Check Polarity of Thermocouples and Lead Wires

Check Polarity of Thermocouples and Lead Wires

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Standard Practice at L&L

The following is the standard practice describing thermocouple polarity for Type K and Type S thermocouples that is used on L&L kilns.

Testing polarity of a Type K thermocouple

You can easily test the polarity of a Type K thermocouples. The negative wire is MORE magnetic than the positive wire. Just put a magnet up to each wire. One will be more magnetic than the other. (This does not work for Type S thermocouples.)

TYPE K (USA)

  • Type K Thermocouple lead wire (Yellow on the outside)
  • Yellow Wire = PLUS (+)
  • Red Wire = MINUS (-)
  • The thermocouples are marked with a (+) and (-). Also the negative (-) is marked with a red marker. The negative wire is MORE magnetic than the positive wire.
  • NOTE: Ground the outside metal foil wrapper to the negative terminal of the control.

TYPE S (USA)

TYPE K (EUROPE)

  • Thermocouple wire (Yellow on the outside)
  • Green Wire = PLUS (+)
  • White Wire = MINUS (-)
  • The thermocouples are marked with a (+) and (-). Also the negative (-) is marked with a red marker. The negative wire is MORE magnetic than the positive wire.

TYPE S (EUROPE)

  • Type S Thermocouple wire (Green on the outside)
  • Orange Wire = PLUS (+)
  • White Wire = MINUS (-)
  • The thermocouples are marked with a (+) and (-). Also the negative (-) is marked with a black marker.

NOTES

  1. See this for information on how thermocouples work.