Are you testing figure of 8 leads the wrong way?
Do you test Figure of 8 leads – if so, it might be pausing to consider - what are you actually testing?
Figure of 8 leads look like they should be testable, especially with those Figure of 8 adaptors floating around — looks straightforward, right? But wait — let’s think about the usual tests we perform on a lead: Earth Continuity, Insulation Resistance (or leakage current), and Polarity.
Figure of 8 leads don’t have an earth conductor – they’re double insulated. That means no earth continuity test is possible. What about insulation? Appliance testers check insulation resistance between the two current carrying conductors (connected together) and earth. So if you perform an insulation test you’ll likely get a “PASS” result that means… nothing.
And of course they’re reversible – flip the plug and the polarity changes – so a polarity test? Not meaningful either.
So what can you do?
- A thorough visual inspection is your most important test.
- A Class II insulation test (or touch leakage test) using an earth probe to the exposed metal parts of the appliance they the lead powers is essential (as per AS3760)
- Continuity and tests on the Active and Neutral conductors or insulation between the two might be helpful - but isn’t specifically mandated under AS/NZS 3760
What about C6 IEC leads (Cloverleaf, Laptop leads etc)?
C6 leads – the type you often used to power laptop power supplies have an active neutral and earth conductors. Other than the socket, they are no different to any other lead so using the right adaptor a standard extension lead test is appropriate. Adaptors are readily available.
