Portable Appliance Testing (PAT Testing) is a key part of maintaining electrical safety in the workplace. But did you know that a surprising number of appliances fail their PAT tests every day?
At MES Pat Testing, we test thousands of appliances every year across offices, shops, schools, rental properties, and construction sites. We’ve seen the same issues come up again and again—most of them avoidable with just a little care and awareness.
Here are the 10 most common PAT testing failures, what causes them, and how to prevent them.
1. Damaged Power Cables
What it is: Frayed, cut, twisted, or exposed wires.
Why it fails: Exposed cables are a serious fire and shock hazard.
How to avoid: Regularly inspect cables and replace any that show signs of wear.
2. Incorrectly Wired Plugs
What it is: Live, neutral, or earth wires connected to the wrong terminals.
Why it fails: Can lead to electric shock or fire.
How to avoid: Always use a qualified person to rewire plugs, and never attempt it unless you know exactly what you’re doing.
3. Wrong Fuse Rating
What it is: A fuse that’s too high or too low for the appliance.
Why it fails: Offers inadequate protection, increasing fire risk.
How to avoid: Check the manufacturer’s rating and ensure the correct fuse is fitted.
4. Loose or Exposed Internal Wiring
What it is: Wires not securely fixed inside plugs or appliances.
Why it fails: Can lead to short circuits or overheating.
How to avoid: Use proper strain relief and ensure wires are clamped securely.
5. Cracked or Damaged Plug Casings
What it is: Physical damage to the plug body.
Why it fails: Can expose live parts or make the plug unsafe to use.
How to avoid: Replace damaged plugs immediately.
6. No Earth Connection (Class I Equipment)
What it is: Appliances that require an earth but have no earth continuity.
Why it fails: Earth is essential for safety in fault conditions.
How to avoid: Never remove earth pins or use 2-core cables on earthed equipment.
7. Overloaded Extension Leads
What it is: Multiple high-wattage devices plugged into one lead.
Why it fails: Causes overheating and high fire risk.
How to avoid: Use proper load distribution and avoid “daisy chaining” extensions.
8. Homemade Repairs or Adaptations
What it is: DIY repairs or alterations using tape, glue, or unsafe connectors.
Why it fails: Non-compliant with safety standards.
How to avoid: Use qualified electricians or engineers for all repairs.
9. Damaged Appliance Casings
What it is: Cracks, holes, or broken housing on the equipment itself.
Why it fails: Can expose internal components and lead to injury.
How to avoid: Remove damaged appliances from use immediately.
10. Lack of Previous Maintenance or Testing
What it is: Appliances that haven’t been inspected or tested in years.
Why it fails: Neglect leads to hidden faults going unnoticed.
How to avoid: Set up a regular PAT Testing schedule with MES Pat Testing.
Protect Your Business With Regular PAT Testing
Failing a PAT test doesn’t just mean your appliance is unsafe—it can also mean you’re putting your team, property, and insurance coverage at risk.
At MES Pat Testing, we make it easy to stay compliant:
- Qualified engineers across the UK
- Same-day reports and certification
- Clear labelling on all tested items
- Guidance on failed appliances and what to do next
Email:enquiries@mespattesting.co.uk
Call: 01376 339 372