Shenhai Explosion-Proof
Explosion-proof electrical equipment must have metal casings that are grounded. Additionally, equipotential bonding is necessary to prevent potential leakage currents due to insulation failure and to avoid the risk of electrical sparks from stray currents igniting explosive gas mixtures.
For such equipment, grounding and equipotential bonding should be implemented in a dual system, where each device is equipped with both internal and external grounding terminals. These terminals must be kept at the same potential and connected to the grounding system to ensure the effectiveness of the grounding and bonding.
Internal grounding should be set up within the wiring compartment (junction box or main chamber), and external grounding should be located on the device’s main casing. This ensures that the device’s major metal components, like the frame, are at the same potential as the ground.
The conductors used for grounding and equipotential bonding must meet a minimum cross-sectional area, S. In a single-phase main circuit, if the cross-sectional area S0 is no more than 16mm², then S should be at least S0. For S0 between 16mm² and 35mm², S should be 16mm². If S0 exceeds 35mm², S should be more than half of S0. If S0 is very small, the minimum cross-sectional area should be at least 4mm².
Each grounding and equipotential bonding device must ensure reliable connections between the conductors and the grounding terminals, with measures to prevent loosening or corrosion.
For portable electrical devices powered by the grid, external grounding can be bypassed, but internal grounding should be conducted using a cable with a grounding core. If powered by a battery pack with ungrounded poles, grounding is not necessary. Additionally, electrical devices with double or reinforced insulation should not be grounded.