Thermocouple Construction of Type T Bare Wire

I only use commercial T/C's, I don't roll my own, so I don't have an answer to your question about the source of the error, other than wire alloys can vary.

I'm curious as why, if you have calibration equipment (including a ice point/cold junction) that is good enough to determine that any particular T/C is outside the published limit-of-error, why not use the error as a correction factor for that given thermocouple? You've gone to the cost and effort of determining the error, use it.

Hello and Thanks, We are manufacturing it and it must be made to special limits, which for type T is quite constraining (.5 degrees C). We cannot correct except to choose a different lot number of bare constantin to pair up with the positive copper leg. Trying to make a TC out of bare 36 AWG wire is a nightmare in itself, a job for a microsurgeon, and I'm afraid we may be killing the patient, (the wire). I'm wondering how resilient our patient is (the 36AWG copper and the 36AWG constantin).

One thermocouple welder I saw went up to 1.1 mm wire, but it didn't say how small it could go. Maybe a search on various models would turn up a good choice.

Ask the people who supply it what they do:

1. Thermocouples
   
2. Thermocouple Wire - K Type, Duplex Insulated
   
3. Thermocouple Wire - T Type, Duplex Insulated
4. Fine Wire Duplex Insulated Thermocouple Wire