Electric locomotives usually have a "continuous" and a "one-hour" rating. The one-hour rating is the maximum power that the motors can continuously develop over a one-hour period without overheating. Such a test starts with the motors at +25 °C (and the outside air used for ventilation also at +25 °C). In the USSR, per GOST 2582-72 with class N insulation, the maximum temperatures allowed for DC motors were 160 °C for the armature, 180 °C for the stator, and 105 °C for the collector. The one-hour rating is typically about ten percent higher than the continuous rating, and limited by the temperature rise in the motor.