I. Introduction

Low-voltage distribution box is the lowest level of power system control and protection facilities, is to protect the safe operation of power systems is the most basic part. It has a great chance of getting in touch with workers. However, due to its large number, wide distribution and mostly low value products, it is often neglected by the equipment power sector, leaving many low-voltage distribution boxes out of control and causing insecurity Produced, increasing the risk of personal electric shock and electrical fire. Therefore, the safety of low voltage distribution box selection and use must draw our attention.

Second, the selection of low-voltage distribution box protection type

Low-voltage distribution box protection type should be based on the conditions of the workplace to choose.

(A) In the relative humidity of not more than 75%, and no dust, no corrosive gases or vapors, non-flammable and explosive substances less dangerous place, the low-voltage distribution box can be used open type.

(B) in the relative humidity of nearly 100% of the wet places and places with corrosive gases or vapors should be used protective type.

(C) can produce a large number of dusty dusty places, dust-proof distribution box should be used.

(D) In ​​the H-1 level, H-2 fire hazard sites with flammable liquids and suspended, buildup combustible dust or combustible fibers, dust-proof type should be used; in the H-3 class of fire with solid flammable substances Hazardous locations, optional protection type.

(E) the selection of dangerous places in the explosion.

(1) Where there is an explosive mixture of gas or vapor

â‘  under normal circumstances can form explosive mixtures Q-1-level places should be used Flameproof, explosion-proof ventilation, inflatable low-voltage distribution box.

â‘¡ Under normal circumstances can not be formed, and in the case of abnormal formation of explosive mixtures Q-2 place, you can choose any kind of explosion-proof type.

â‘¢ Under normal circumstances can not be formed, and under normal circumstances can form explosive mixtures, but less likely Q-3-level places, the choice of sealed type.

(2) Where there is an explosive mixture of dust or fiber.

â‘  Under normal circumstances can form explosive mixtures G-1 place, you can choose any one flameproof, explosion-proof ventilation, inflatable.

â‘¡ Under normal circumstances can not form under normal circumstances to form explosive mixtures G-2-level places, the optional dust-type.