Testing Your Work

After completing any electrical work, you should test the installation to verify it is safe before energising it. This is required by BS 7671 and is good practice even for simple jobs.

What to Test

Visual Inspection

Before any testing with instruments:

• All connections are mechanically sound (no loose screws, no bare conductors outside terminals)
• All earth conductors are connected and properly sleeved green/yellow
• No insulation damage from staples or drilling
• Correct cables used (size matches circuit)

Continuity Test

Use a continuity tester or multi-meter to verify:

• Ring final: end-to-end resistance of L, N, and E conductors
• Earth continuity: from CPC at socket/light back to consumer unit

Polarity Check

Verify that at each outlet:

• L terminal is connected to L conductor (brown/red)
• N terminal is connected to N conductor (blue/black)
• Reversed polarity is dangerous — fuses blow but equipment stays live when switched off

Insulation Resistance

More advanced — requires an insulation resistance tester (megger). Tests for leakage between conductors and between conductors and earth. Minimum 1MΩ between L and N, and between either conductor and earth.

After Testing

If all tests pass, re-energise the circuit, test each outlet for correct voltage, and verify the protective devices operate correctly.