Inspection Standards | Household Plugs and Sockets Inspection Standards and Methods

1. Basic inspection

1. Appearance logo

   • Mandatory marking: rated current (A)/voltage (V), power symbol, manufacturer information, model, certification mark

   • Symbol specification: L (live), N (neutral), ⏚ (ground)

   • Surface quality: no cracks/pores/oxidation, uniform coating on metal parts

2. Size compliance

   • Pin and socket tolerance matching (gauge detection)

   • Anti-misplugging design: high-voltage plugs cannot be inserted into low-voltage sockets, and plugs with different numbers of poles cannot be plugged into each other

2. Core Security Items

3. Protection against electric shock

   • Live parts are not accessible after mating (even if tool-free disassembly parts are removed)

   • Protective door: automatically shields the live socket when the plug is pulled out

   • Enhanced protection type: 1mm probe cannot touch live parts

4. Grounding measures

   • The grounding pin has priority contact: when inserted, it is grounded first and then powered on; when pulled out, it is powered off first and then grounded

   • Grounding resistance ≤ 0.05Ω (between terminal and metal parts)

   • Ground terminal anti-corrosion (silver plating or equivalent process)

5. Terminal reliability

   type	Require
   Screw terminals	Clamping bimetallic surface, preventing wire damage, corrosion resistance, and loosening
   Screwless terminals	Supports hard/soft copper wire, resists mechanical/electrical/thermal stress, and does not loosen during installation

6. Structural safety

   • Socket elastic contact: at least two side metal contacts

   • Insertion gap ≤ 1mm, grounding socket anti-rotation lock

   • Cable entry for complete mechanical protection

3. Performance Testing

7. Environmental tolerance

   • Aging resistance: 70℃±2℃/168h → no cracks or stickiness

   • Moisture-proof: 40℃±2℃/91-95%RH/48h → insulation meets standards

8. Electrical performance

   • Insulation resistance : pole-body ≥5MΩ, pole-pole ≥2MΩ

   • Hi-pot test : 2kV/50Hz/1min → no flashover or breakdown

   • Temperature rise limit (after life test):

     • Terminal ≤45K, touchable metal ≤30K, non-metal ≤40K

9. Durability

   • Breaking capacity : 30 times/minute, 100 plugging and unplugging (≤16A/250V) → no continuous arc

   • Life test : Rated current/0.8 power factor plug and unplug 5000 times → no wear/deterioration/loosening

4. Machinery and Materials

10. Mechanical strength

    • Compliant extraction force (to prevent accidental removal)

    • Impact test: housing/protective door resistance to mechanical stress

11. Heat-resistant and flame-retardant

    • 100℃ ball pressure test : indentation diameter ≤ 2mm

    • Glow-wire test :

      • Current-carrying parts insulation: 850℃ → self-extinguishing within 30s

      • Insulation of non-current-carrying parts: 650℃ → Silk paper will not catch fire

12. Rust and corrosion prevention

    • No rust on iron parts after salt spray test

    • Corrosion-resistant metal for current-carrying contacts

5. Key clearance requirements

13. Spacing standards

    • Creepage distance : the distance along the surface between different potentials (depending on voltage level)

    • Electrical clearance : the straight-line distance between charged bodies

    • Penetration distance : insulation seal thickness

    See the standard diagram for the schematic diagram, and a special caliper is required for measurement

Inspection process recommendations

1. Appearance logo → 2. Dimensional gauges → 3. Anti-electric shock verification → 4. Ground resistance test

2. Terminal strength → 6. Hipot/insulation test → 7. Life/breaking test → 8. Flame retardant/material testing

⚠️ Recall Warning : Giant Helmet Recall Case Highlights Risk of Structural Failure: If the socket fails the impact energy absorption (such as shell rupture) or flame retardancy test , it may cause fire/electric shock accidents.