Founded in
Certified Company
Excellent Quality
Leqing Naza Electric Power Technology Co., Ltd. is located in Liushi, Zhejiang, the capital of electrical appliances in China. The company's main business is Low voltage circuit breaker series,Fuse series,Low voltage transformer series,Surge protector,Terminal series Wait for the product. The company adheres to the development philosophy of combining research and development with the market, and synchronizing innovation with customers, constantly developing products that meet customer needs.
For a century the circuit breaker was judged by two mechanical moments—closing and opening. Its remaining life was spent in silence, heating, ageing, vibrating, yet revealing nothing until a fault occurred. Today the same moulded case has become an edge computer: voltage and current waveforms are sampled at 8 kHz, contact wear is estimated by AI, firmware is updated over the air, and carbon-footprint data are streamed to sustainability dashboards. This transformation is not cosmetic
This paper translates the most common national codes (GB 50303-2023, GB/T 36291, NB/T 42086, IEC 60364-5-52, NEC Art. 240 & 250) into step-by-step craft rules for electricians who actually tighten the screws. It concentrates on the external cabling side—how the three system conductors (L, N, PE) must be landed on breaker, bus-bar and terminal strip inside residential or light-commercial switchboards ≤ 400 V. Factory internal wiring is mentioned only where it affects field work.
A circuit breaker is a two-faced device. In its “closed” life it must carry the everyday load current for decades without nuisance heating. In its “open” life it must clear the worst short-circuit the utility can deliver within milliseconds.