Explosion proof lighting distribution boxes, as the core control equipment of lighting systems in flammable and explosive environments, are mainly used in explosive hazardous environments such as petroleum, chemical, and coal mines. They can provide power distribution, equipment start-up, and maintenance support for lighting or power lines.

The selection of explosion-proof lighting distribution boxes should revolve around the three core elements of "lighting requirements, environmental risks, and compliance", with a focus on key parameters that are compatible with the lighting system, to avoid "functional mismatches" of general-purpose distribution boxes

Environmental adaptation: Dual matching of hazard level and protection level

Corresponding hazard level:

Explosive gas environment (such as gas stations, chemical workshops): Zone 1 needs to choose explosion-proof type (Ex d), Zone 2 can choose increased safety type (Ex e), and it is necessary to clarify the gas group (such as IIA, IIB, covering common propane, ethanol, etc.) and temperature group (such as T4, surface maximum temperature ≤ 135 ℃, to avoid igniting flammable substances in the lighting area); ​

Combustible dust environment (such as flour mills and coal bunkers): Dust explosion-proof type (Ex tD) should be selected for zone 20/21, and dust enhanced safety type can be selected for zone 22, with a protection level of at least IP65 (to prevent dust from entering the interior of the box and affecting the insulation of the lighting circuit); ​

Special environment: In humid environments (such as underground mines and aquatic processing workshops), additional waterproof performance (IP66 or above) is required. In corrosive environments (such as beaches and acid pickling workshops), 304 stainless steel shells or fluorocarbon spray anti-corrosion treatment should be selected. ​

Misconception reminder: Explosion proof power distribution boxes should not be used as a substitute for lighting distribution boxes. The circuit overload protection parameters (such as current threshold) of the power box do not match the lighting load (mostly low-power LEDs and fluorescent lamps), which can easily lead to protection failure. ​

Circuit configuration: precise adaptation to the number and power of lighting loads

Number of circuits: determined according to the grouping requirements of lighting fixtures. If the workshop is divided into 3 groups of lighting according to the area, 3 independent lighting circuits need to be configured, each with an independent circuit breaker (for easy separate control and fault diagnosis); ​

Current and power: Calculate the circuit current based on the total power of a single lighting load (formula: current=power/voltage, for example, under 220V voltage, 1000W lighting load current ≈ 4.5A). The rated current of the circuit breaker should be ≥ 1.2 times the calculated current (with safety margin reserved to avoid long-term full load operation), and the rated current of the main switch should be ≥ the sum of the currents of each circuit; ​

Special load: If the lighting system includes emergency lighting (such as explosion-proof emergency lights), a separate emergency circuit needs to be configured, and the emergency circuit needs to have the function of "automatic switching after main power failure" (which can be equipped with an emergency power module or an external emergency power supply) to ensure that the emergency lighting starts normally in case of power failure. ​

Component selection: Focusing on the low-power characteristics of lighting loads

Core components: Circuit breakers should be selected as "lighting protection type" (such as DZ47-60 C-type circuit breaker, with an instantaneous tripping current of 5-10 times the rated current, suitable for the starting characteristics of lighting loads), and the use of power protection type (D-type, with an instantaneous tripping current of 10-20 times, prone to accidental tripping) is prohibited; ​

Wiring terminals: Select terminals that are compatible with the specifications of lighting cables (such as terminals corresponding to 1.5-2.5mm ² cables), ensure that the wires are firmly connected, and avoid virtual connection problems caused by thin cables and large terminals; ​

Indicator lights and switches: Explosion proof type (such as LED explosion-proof indicator lights) should be selected for the lighting circuit inside the box. It is recommended to distinguish colors (such as green indicating normal operation and red indicating faults). External operation switches should be equipped with waterproof and dustproof covers (protection level ≥ IP54).