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 thermocouple. 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)

1. Type K Thermocouple lead wire (Yellow on the outside)
2. Yellow Wire = PLUS (+)
3. Red Wire = MINUS (-)
4. 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.
5. NOTE: Ground the outside metal foil wrapper to the negative terminal of the control.

TYPE S (USA)

1. Type S Thermocouple lead wire (Green on the outside)
2. Black Wire = PLUS (+)
3. Red Wire = MINUS (-)
4. The thermocouples are marked with a (+) and (-). Also, the negative (-) is marked with a black marker.
5. See this note about the mismatched colors on Type S thermocouples vs the thermocouple extension wire in the USA.

TYPE K (EUROPE)

1. Thermocouple wire (Yellow on the outside)
2. Green Wire = PLUS (+)
3. White Wire = MINUS (-)
4. 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)

1. Type S Thermocouple wire (Green on the outside)
2. Orange Wire = PLUS (+)
3. White Wire = MINUS (-)
4. 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.