防爆レベルT4の温度は？

The T4 classification specifies that electrical devices must operate with a maximum surface temperature of no more than 135°C. Products with a T6 rating are applicable across various temperature groups, whereas T4 devices are compatible with T4, T3, T2, and T1 conditions.

電気機器の温度グループ	電気機器の最大許容表面温度(℃)	ガス/蒸気の発火温度 (℃)	適用デバイス温度レベル
T1	450	＞450	T1~T6
T2	300	＞300	T2~T6
T3	200	＞200	T3~T6
T4	135	＞135	T4~T6
T5	100	＞100	T5~T6
T6	85	＞85	T6

The reason T6 is not typically used is that many devices, particularly those requiring high power or consisting of purely resistive circuits, are unable to achieve the stringent low-temperature conditions stipulated by the T6 classification.