Explosion-proof junction boxes

Figure 17-24. Standard explosion-proof junction boxes ond conduit fittings. [Courtesy of Crouse-Hinds Electrical Construction Materials, a division of Cooper industries, Inc. ...

P ALL WIRING BROUGHT TO EXPLOSION PROOF JUNCTION BOX REPRODUCTION OF STAFDARD NO 53.02-0... 

A box or fitting must be installed at each conductor sphce connection point, receptacle, switch, junction point, or pull point for the connection of conduit system. In Division 1 areas only explosion-proof boxes or fittings are allowed. General purpose gasketed cover type fittings are allowed in Division 2 areas. 

To retard corrosion and to facilitate future maintenance (e.g., allow the non-destructive removal of threaded Junction box covers), all threaded connections should be lubricated with an antiseize compound which will not dry out in the environment. If lubricant is applied to the threaded (or flanged) portion of covers of explosion-proof enclosures, the lubricant must have been tested and approved as suitable for flame path use. It is cautioned that some lubricants contain silicone, which will poison most catalytic gas detector sensors and should not be used near gas detectors. 

The explosion-proof design includes the use of conduit with special sealed connections around all junction boxes. 

At present, measures such as replace the general electrical equipment and damaged cables can be used to solve not use explosion-proof electric equipment and short circuit fault of the electric cable thoroughly. But now there is no way to completely solve the problem of electrical equipment lost its explosion-proof ability, and the most common method used in coalmine is intensive inspection. The types of electrical equipment that lost its explosion-proof ability showed in accident cases have been collected, and got 5 common types of electrical equipments/devices, these 5 types are electrical switches, miner s lamp, exploder, electric coal drill, junction box, and specific distribution is shown in Figure 2. From the figure, we can know electrical switches, miner s lamp and junction box are the 3 main types of equipments/devices that prone to lose its explosion-proof ability, accounted for about 76.93% in total. 

Divided the external-cause ignition sources into electrical fire and operating fire. 3 types of generic acts are included in Electrical fire electrical equipment lost its explosion-proof ability, not use explosion-proof electric equipment, short circuit fault of the electric cable. Electrical switches, miner s lamp and junction box are the 3 main types of equipments/devices that prone to lose its explosion-proof ability, accounted for about 76.93% in total. 

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