Knowledge article · Pillar
Electrical Testing Explained
Electrical testing covers fixed-wire inspection, portable appliance testing and specialist checks that prove an installation and its equipment are safe and compliant.
Electrical testing is the umbrella term for the inspections and measurements that prove an electrical installation, and the equipment connected to it, remain safe to use. It ranges from full fixed-wire inspection to portable appliance testing and specialist checks such as thermographic surveys.
The two pillars: fixed and portable
The two most common forms of testing serve different purposes:
- Fixed-wire testing examines the permanent installation — the incoming supply, distribution boards, circuits, protective devices and accessories. It is documented on an Electrical Installation Condition Report (EICR).
- Portable appliance testing (PAT) checks equipment that plugs into the installation — from kettles to IT equipment — combining a visual inspection with electrical tests where appropriate.
Together they give a complete picture: the wiring that carries the power, and the appliances that draw it.
Why testing is risk-based, not calendar-based
There is a common myth that the law fixes a single testing interval. In reality, the Electricity at Work Regulations 1989 require installations and equipment to be maintained in a safe condition, and the practical way to demonstrate that is periodic inspection at an interval justified by risk. A busy commercial kitchen and a low-use office store room do not need the same frequency. The correct approach is to let the previous report — or a documented risk assessment — set the interval.
What a competent inspection involves
- A combination of visual inspection and dead and live testing using calibrated instruments.
- Measurement of key values such as earth fault loop impedance, insulation resistance and RCD trip times against the limits in BS 7671.
- Clear coding of any issues and a plain-English report so duty holders can act.
Turning results into action
Testing only adds value if the findings are acted on. Where an EICR is unsatisfactory, the remedial priorities should be addressed and re-certified by a competent person. Where portable appliances fail, they should be removed from service until repaired or replaced.
Building a testing programme
Across a property or portfolio, the most effective approach is a single testing programme that schedules fixed-wire testing, PAT, emergency lighting and fire alarm checks together, with due dates tracked centrally. That coordinated view keeps a building demonstrably safe and avoids the gaps that arise when each system is managed in isolation.
Frequently asked questions
What is the difference between fixed-wire testing and PAT?
Fixed-wire testing (an EICR) inspects the permanent installation — the wiring, distribution boards and accessories. Portable appliance testing checks plug-in equipment. Both are part of a complete electrical testing regime, and both are risk-based rather than fixed by law to a single interval.
How often should electrical testing be carried out?
Frequencies are risk-based. Fixed-wire testing is commonly every five years for commercial premises and at change of tenancy or every five years for rented homes, while portable appliances are tested on a schedule set by risk. The previous report or a formal risk assessment should always set the actual interval.
This article provides general guidance and distinguishes legislation, British Standards and good practice. It is not legal advice. Always confirm the specific duties applying to your property and tenure.