Fixed Wire Testing vs PAT Testing: What’s the Difference and Why Both Matter?

Fixed wire testing and PAT testing are two separate but equally essential electrical-safety measures. Fixed wire testing checks the condition of your building’s electrical installation, while PAT testing ensures your portable appliances are safe. You need both to maintain compliance, reduce risks, protect your workforce and tenants, and meet legal duties under UK regulations.

This blog explains the difference between fixed wire testing and PAT testing, when each is required, how they complement each other, and why organisations should integrate both into their compliance planning. It also shows how Global Compliance UK supports businesses, landlords and commercial property owners through reliable electrical testing services.

If you would like to request a quote or book a service, please go to our contact page.

Why Understanding the Difference Matters

Many electrical risks originate from two areas: the fixed electrical installation and the portable equipment plugged into it. These are separate systems, each with different failure patterns, risk profiles and legal considerations.

Fixed wire issues include:

• Deteriorated wiring and old circuits

• Overloaded sockets

• Damaged distribution boards

• Outdated protective devices

• Loose or faulty connections

• Lack of adequate RCD protection

Portable appliance issues include:

• Damaged cables or plugs

• Poorly repaired equipment

• Loose internal components

• Incorrect fuses

• Worn insulation

• Overheating or misuse

Both types of faults can lead to incidents such as electric shocks, electrical fires, equipment failure and operational downtime. Because they arise from different sources, fixed wire testing and PAT testing target different risks. Only by using both can you ensure a safe environment.

What Fixed Wire Testing Covers

Fixed wire testing focuses on the permanent electrical infrastructure of your building. This includes everything that forms part of the electrical installation:

• Lighting circuits

• Socket outlets

• Distribution boards

• Switchgear

• Cabling and trunking

• Hard-wired equipment

• Earthing and bonding systems

• RCDs and protective devices

This procedure is formally known as an Electrical Installation Condition Report (EICR). It assesses the safety of the installation and identifies deteriorating components, overloading, faulty wiring or outdated protection that could lead to danger.

During fixed wire testing, a qualified electrical inspector conducts:

• Visual inspection of circuits and components

• Electrical tests such as continuity, insulation resistance, polarity and earth-fault loop impedance

• Assessments of protective devices

• Condition reports with coded observations

• Recommendations for remedial work

• Verification of compliance with BS 7671 (IET Wiring Regulations)

The final EICR classifies issues using codes such as:

• C1: Immediate danger, requires urgent action

• C2: Potentially dangerous

• C3: Improvement recommended

• FI: Further investigation required

These results help duty holders plan corrective work.

What PAT Testing Covers

PAT testing focuses on portable appliances, meaning any equipment that plugs into the electrical installation using a flexible cable and plug. Common examples include:

• Kettles

• Computers

• Printers

• Extension leads

• Portable heaters

• Monitors

• Power tools

• Catering appliances

A comprehensive PAT testing programme combines:

User Checks

Quick visual checks carried out by staff before using equipment.

Formal Visual Inspection

A more detailed inspection by a competent person, looking for damage, wear and misuse.

Electrical Testing

Where appropriate, tests such as:

• Earth continuity

• Insulation resistance

• Polarity tests

• Functional checks

Once an appliance passes, it is labelled and recorded with a retest date. Failed appliances are removed from service until repaired or replaced.

Key Differences Between Fixed Wire Testing and PAT Testing

Although both aim to improve electrical safety, fixed wire testing and PAT testing differ significantly in their purpose and scope.

Fixed Wire Testing Focuses on Infrastructure

It checks the safe operation of your:

• Electrical circuits

• Hard-wired systems

• Distribution boards

• Wiring integrity

• Safety devices

This ensures your building complies with BS 7671.

PAT Testing Focuses on Plug-In Equipment

It ensures safety at the point of use by checking:

• Cables

• Plugs

• Appliance casings

• Internal insulation

• Electrical continuity

This ensures portable equipment is safe for daily use.

Different Legal and Regulatory Drivers

Fixed wire testing underpins compliance with the Electricity at Work Regulations 1989. PAT testing supports the same regulations but focuses on equipment maintenance.

Different Testing Intervals

Fixed wire testing is typically required every:

• 1–3 years for industrial or high-risk sites

• 3–5 years for standard commercial premises

• 5+ years for low-risk environments

PAT testing intervals depend entirely on risk and usage. Some appliances may require testing every few months; others every few years.

Why You Need Both for Complete Safety

Many organisations mistakenly believe that only one of the two types of testing is necessary. This is not the case. Both serve separate functions, and relying on only one exposes gaps in your safety regime.

Fixed Wire Testing Does Not Detect Appliance Faults

You may have a perfect electrical installation, but a portable appliance with:

• A frayed cable

• An exposed conductor

• An overloaded adaptor

• A loose connection inside the plug

can still cause an electric shock or fire.

PAT Testing Does Not Detect Wiring or Circuit Faults

A fully tested kettle or heater provides no protection if:

• The circuit is overloaded

• The socket is damaged

• The wiring insulation has deteriorated

• The protective devices fail to operate

Both Reduce Liability and Strengthen Compliance

For employers and landlords, using both types of tests demonstrates:

• A proactive safety culture

• Maintenance of safe equipment

• Compliance with legal duties

• Evidence for insurance requirements

• A reliable risk-management programme

If an electrical incident occurs and testing has not been carried out appropriately, investigations may conclude that the duty holder failed to maintain safe conditions.

Designing a Combined Testing Strategy

To manage compliance effectively, you need a structured plan that incorporates both fixed wire and PAT testing. Consider the following framework.

Build a Full Asset and Installation Inventory

Record all circuits, distribution boards, fixed wiring and appliances. Include:

• Locations

• Risk categories

• Usage

• Environmental exposure

• Previous failure history

Apply Risk-Based Testing Intervals

High-risk equipment needs more frequent testing than low-risk equipment. Examples:

• Portable power tools → frequent PAT testing

• Server rooms → regular fixed installation checks

• Office appliances → periodic PAT testing

• Workshops → frequent inspections for both installation and appliances

Schedule Testing to Minimise Disruption

Many businesses choose to conduct:

• Fixed wire testing outside peak times or in stages

• PAT testing during quieter periods or department-by-department

This reduces downtime and improves efficiency.

Document All Results

For compliance, each task should generate:

• An updated asset register

• A PAT report

• Pass/fail details

• EICR documents

• Retest dates

• Repair and remedial logs

Follow Up on Remedial Work

Any defects identified in the EICR or PAT report must be addressed quickly. This may include:

• Rewiring or circuit repairs

• Replacement of outdated boards

• Upgrading protective devices

• Repairing or retiring faulty appliances

Common Misunderstandings About Electrical Testing

Even experienced duty holders misunderstand the purpose of each type of test. Here are some misconceptions.

“PAT testing covers the whole building”

PAT testing only covers portable appliances. It does not check wiring or circuits.

“Fixed wire testing will find all electrical faults”

It does not detect damage to individual appliances.

“We only need electrical testing once every few years”

Appliances deteriorate far more quickly than wiring. PAT testing must be more frequent.

“New equipment doesn’t need testing”

Even new appliances should undergo visual checks before use.

“If the lights work, the wiring must be fine”

Circuit faults do not always cause visible symptoms. Testing is essential.

How Global Compliance UK Supports Your Electrical Safety Programme

Global Compliance UK provides comprehensive testing services for organisations of all sizes. Our goal is to ensure both the installation and the appliances connected to it remain safe, compliant and well-maintained.

What We Provide

• Fixed wire testing by qualified inspectors

• Detailed EICR reporting

• Portable Appliance Testing for all appliance classes

• Support with asset registers and test scheduling

• Clear pass/fail reporting and labelling

• Advice on risk-based testing intervals

• Remedial work recommendations

• Professional documentation suitable for audits and insurance

To book electrical testing or request assistance, use our contact page.

Conclusion

Fixed wire testing and PAT testing work together to create a complete electrical-safety system. One protects your building, the other protects the appliances your people use every day. Both are essential for compliance, accident prevention and responsible management. If you want a fully managed, risk-based electrical-safety programme for your business or property, the team at Global Compliance UK is ready to support you through our contact page.