Which Explosion-Proof Level Is Higher, AT2 or BT4

The order of explosion-proof ratings is straightforwardly recorded as A < B < C.

III	C	T 135℃	Db	IP65
III Surface dust		T1 450℃	Ma	IP65
		T2 300℃	Mb
		T3 200℃
	A Flammable flying flocs		Da
		T4 135℃
			Db
	B Non conductive dust	T2 100℃	Dc
	A Conductive dust	T6 85℃

For the ‘T’ rating, it’s remembered by its numerical order: the larger the number, the higher and safer the rating.

Therefore, an explosion-proof rating of BT4 surpasses that of AT2.

It’s important to clarify that ‘T’ denotes the maximum surface temperature of electrical devices. A T4 rating, set at 135°C, is applicable for explosive gases with flash points exceeding 135°C.