How To Deal With Poor Contact Of The Neutral Block?
When there is poor contact at the neutral block, the four step process of "power-off diagnosis repair verification" should be followed to ensure the safe operation of the electrical system.
Safe power outage
Firstly, turn off the higher-level power supply, use a voltage tester to confirm that there is no voltage, and then hang a warning sign. For important loads, it is recommended to use bypass power supply or dual power switching devices to avoid prolonged power outages.
Three-level diagnostic method
Visual inspection: observe whether the terminals are blackened (overcurrent traces), whether the screws are loose, and whether the wire ears are cracked
Contact test: Use a contact resistance tester, and the measured value should be ≤ 0.1 Ω (according to GB/T 20248.1 standard)
Temperature rise detection: Use an infrared thermometer to detect under load, and the temperature rise should be less than 40K (according to IEC60529 requirements)
Specialized repair
Mechanical treatment: Polish the oxide layer with No. 0 sandpaper and apply conductive paste (in accordance with the conductivity requirements of GB/T 26218.1)
Structural reinforcement: Adopting double line parallel connection method to increase the contact area; Use self-locking terminal caps for loose terminals
Material upgrade: Replace with copper aluminum transition terminals (certified through 1000 hour salt spray test)
Quality Verification
After running under load for 1 hour, retest:
Voltage drop should be ≤ 3% of rated voltage (according to GB/T 15576)
Harmonic content increase<5% (detected using APQ power quality analyzer)
Preventive measures:
Conduct infrared thermal imaging scans every quarter and detect contact resistance annually; It is recommended to use pre insulated terminals for new installation, with a tightening torque controlled at 2.5N · m (according to the manufacturer's specifications). Online monitoring devices can be installed in important locations to monitor contact status in real-time.
