For flameproof instruments, what type of wiring box should be used?
Thread Content
I would like to ask: in Zone 2 explosion-proof areas, explosion-proof instruments should be used. For cables, non-intrinsic safety cables are used; for gland connections, flameproof glands are employed. Therefore, flameproof junction boxes can be used for wiring boxes, which is no problem and understandable. So, can a junction box be an increased-safety junction box? Is there such a standard? If it can be used, there is one question: since the cable is not intrinsically safe, the connection points of the cable (the terminals in the junction box) need to have enhanced safety certification (the terminals are treated specially so that no sparks are generated under normal conditions). But then, in the event that a short circuit occurs in the cable and sparks are produced, or even an explosion takes place, won’t the enhanced safety box fail to provide explosion protection? The flameproof box is fine; an explosion inside it won’t cause any problem**……
Enhanced safety junction boxes can be used for junction boxes, but certain conditions must be met. The usage requirements for increased-safety type junction boxes differ from those for flameproof type junction boxes, mainly in terms of explosion protection properties, protection rating, enclosure material, and structure. Regarding the question you raised about sparks occurring due to cable short circuits, the enhanced safety box also possesses explosion-proof properties. The design concept of the increased safety type junction box is that, even in the event of abnormalities such as short circuits, overloads, or sparks in the electronic devices inside it, it will not cause explosive gases to form outside. Therefore, even if sparks are generated due to a cable short circuit, the increased safety type junction box can effectively prevent these sparks from spreading into the external environment, thereby achieving explosion protection. However, it should be noted that the explosion-proof properties of increased-safety junction boxes cannot replace those of flameproof junction boxes. In some special environments, explosion-proof junction boxes are still necessary. Which type of junction box to use depends on the actual operating environment and the requirements of the equipment. .
A intrinsically safe circuit is one in which, even in the event of a short circuit, its energy is not sufficient to cause an explosion.
I think the enhanced safety type junction box can be used.