Type J thermocouple
Fe / Cu-Ni · -210 … 1200 °C · IEC 60584-1
At a glance
- Conductors (+ / −)
- Fe / Cu-Ni
- Range of the reference function
- -210 … 1200 °C
- Sensitivity at 300 °C
- 55.35 µV/°C
- Class 1 tolerance
- ±1.5 °C or ±0.004 × |t|, whichever is larger, -40 to 750 °C
- Class 2 tolerance
- ±2.5 °C or ±0.0075 × |t|, whichever is larger, -40 to 750 °C
Wire colours
| Positive | Negative | Sheath / Jacket | |
|---|---|---|---|
| IEC 60584-3 (international) | black | white | black |
| ASTM E230 / ANSI (USA), extension wire | white | red | black |
Colours identify the type, not the quality of the cable. Older national codes (e.g. BS 1843, DIN 43714, JIS) used other colours; check before reusing existing cable.
EMF at common temperatures (0 °C reference)
| Temperature (°C) | EMF (mV) | Sensitivity (µV/°C) |
|---|---|---|
| -200 | -7.890 | 21.85 |
| 0 | 0.000 | 50.38 |
| 100 | 5.269 | 54.36 |
| 200 | 10.779 | 55.51 |
| 300 | 16.327 | 55.35 |
| 400 | 21.848 | 55.15 |
| 600 | 33.102 | 58.49 |
| 800 | 45.494 | 64.63 |
Typical use and limits
Iron against constantan: high output and common on older plastics and moulding machinery. The iron leg oxidises quickly in air above about 550 °C and rusts in damp conditions, so type J suits reducing or inert atmospheres, vacuum and moderate temperatures.
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