T Codes

T Codes or Temperature Codes

The third result, as mentioned above, of the new U/ L requirements for explosion-proof motors is that all XP motors must be marked to indicate the maximum operating surface temperature. A "T" Code is used as the Temperature identification value and it is taken from the National Electric Code. The "T" Code is based on the minimum ignition temperature of the substances to be found in the hazardous location. (Ignition temperature is when substance will start to burn or explode,) The code, when marked on a motor nameplate, represents the highest temperature that could be obtained on the motor surface under any normal or abnormal operating conditions including locked rotor, single phasing or overloading, and is chosen to be below the ignition temperature of the substance in the hazardous area. The "T" Code designations apply to motors and other types of electrical equipment subject to hazardous location classification.