Yeyiphi iNqanaba loBuqhushumbo-bubungqina obuphezulu, AT1 okanye BT4

Ukuhlelwa kobungqina bokudubula kwe-IIB ngokwendalo ngaphaya kwe-IIA, kunye neklasi yeqondo lokushisa le-T4 libonelela ngamaqondo aphantsi kwaye akhuselekileyo kune-T1. Ngaloo ndlela, I-BT4 inomlinganiselo ophezulu wobungqina bokudubula.

III	C	T 135℃	Db	IP65
III Uthuli olungaphezulu		T1 450℃	Ma	IP65
		T2 300℃	Mb
		T3 200℃
	A Iindiza eziphaphazelayo ezinokutsha		Kwaye
		T4 135℃
			Db
	B Non conductive dust	T2 100℃	Dc
	C Uthuli oluqhubayo	T6 85℃

Iklasi nganye yobungqina bokudubula ijolise kwiinjongo ezithile zokhuseleko. Ulwazi oluthe kratya lunokufumaneka ngokukhangela kwi-Shenhai Explosion Proof.