Plug Checker

Learn how a plug pin gauge (Plug Checker) helps identify counterfeit and unsafe BS1363 plugs and chargers. A useful tool during PAT testing visual inspection.


plug size gauge

Electrical Safety First (the UK’s electrical safety charity) sell a simple Plug Checker (plug pin gauge) designed to help identify substandard and counterfeit plugs, chargers and adaptors. These types of products are increasingly encountered during inspection and PAT testing, see our examples of counterfeit and dangerous electrical equipment for real-world cases.


plug should easily slide into the holes

A plug should be able to slide easily into the holes on the card. This counterfeit USB charger can only fit part way before becoming stuck, indicating that the pins are incorrectly spaced.


plug must completely cover the red zone

The plug must also completely cover the red zone on the gauge to meet British Standards (BS1363). The gauge clearly shows this dangerous plug adaptor is an incorrect size and should not be used.


gauge showing plug is not correct size

This counterfeit plug has a fake BSI Kitemark logo and registration number, but the gauge shows it's not correct size. BSI registration numbers can be looked up on the BSI website. The licence number on this plug, KM41231, is not registered.


checking length of pins

The length of the pins and sleeves can also be checked against the gauge on the side of the card.


What to do if a plug fails the gauge

  • Stop using it immediately – don’t try to “see if it’s OK”.
  • Contact the retailer to report it as potentially unsafe and request a refund/replacement.
  • Report it to Trading Standards (or to Electrical Safety First via their enquiries email).

The Plug Checker can be purchased from Electrical Safety First. See: Electrical Safety First – Plug Checker.


Please note that Plugtest Ltd does not supply the plug pin gauge featured in this article. All enquiries regarding purchase, availability, or distribution should be directed to Electrical Safety First.