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Electrical safety is often taken for granted until something goes wrong. Whether you’re fault finding in a domestic property or carrying out maintenance in a commercial building, the safe use of test equipment is important. That’s where GS38 comes in.

GS38, officially titled Electrical test equipment for use on low voltage electrical systems, is a guidance note published by the Health and Safety Executive (HSE). It’s not a legal requirement in itself, but it supports compliance with the Electricity at Work Regulations 1989. Essentially, GS38 offers practical advice on how to safely use voltage detectors, test lamps, multimeters, and other electrical testing gear in low-voltage environments.

It’s not just theory either, GS38 has very real consequences in terms of safety. Following it helps prevent electric shocks, burns, and other injuries that could occur from using faulty or unsuitable equipment.

The HSE (Health and Safety Executive) issues GS38, and it’s widely recognised across the electrical industry. Many employers, training centres, and inspection bodies treat GS38 as the minimum acceptable standard for anyone working on or near live electrical equipment.

You can find out more and download the file directly from the HSE site: 

https://www.hse.gov.uk/pubns/books/gs38.htm

Testing electrical installations is inherently risky. Even something as simple as checking for voltage on a socket faceplate could be hazardous without proper equipment. GS38 helps reduce these risks by setting clear expectations for what constitutes safe equipment and safe working practices.

One of GS38’s core principles is protecting the user from electric shock. This doesn’t just mean using insulated tools, but also ensuring that test leads and probes do not expose more live parts than absolutely necessary. A small oversight can make all the difference when dealing with potentially fatal voltages.

According to GS38, test probes should be designed to limit exposure to conductive parts. Tips should be as short as practical no more than 4mm of exposed metal and well-shrouded. Leads should also be robust and resistant to mechanical damage, with good strain relief at both ends.

GS38 doesn’t just focus on protecting the person using the tester it also aims to protect the equipment under test. Poorly designed probes can slip and cause a short circuit between conductors, leading to arcing, blown fuses, or even more serious equipment failure. Safe design reduces these risks significantly.

GS38 strongly recommends the use of two-pole voltage indicators over simple neon screwdrivers or single-pole testers, which can be misleading or even dangerous. Two-pole testers should be CAT III or CAT IV rated, depending on the installation being tested.

Multimeters can be used, but only if they’re of the right quality. They must be fused, properly rated, and ideally fitted with GS38-compliant test leads. Cheaper models sold online often don’t meet these requirements and that’s where risk creeps in.

Clamp meters, used to measure current without direct contact, generally fall outside the stricter GS38 probe requirements, but their leads should still be inspected for insulation integrity.

To verify that a voltage indicator is working correctly, GS38 advises the use of a proving unit. This is vital before and after testing a circuit to confirm your tester wasn’t faulty. Test lamps are allowed but should comply with specific GS38 criteria regarding voltage rating and probe design.

Leads and probes must be fully insulated, leaving only a very short metal tip exposed. This limits the chance of the probe contacting anything it shouldn’t.

One of the most quoted elements of GS38 is the limit of 4mm maximum exposed metal on probes. More than that, and you’re increasing your risk unnecessarily especially in confined or awkward testing spaces.

Probes must include finger guards to prevent the user’s hand from slipping forward. Equally important is the design of grip areas. Smooth, round probes that are difficult to hold can lead to unsteady hands, which is the last thing you want during a live test.

GS38 insists on regular inspection of test leads for damage, wear or degradation. Leads must also have the appropriate overvoltage category rating CAT III for distribution-level testing or CAT IV for testing at the origin of the supply.

GS38 is primarily aimed at low voltage systems, defined in the UK as systems not exceeding 1000V AC or 1500V DC. This includes most domestic and commercial installations.

From rewiring a home to maintaining a commercial distribution board, GS38 applies across the board. It’s not just for big industrial jobs anyone working with electrical test equipment should be aware of the guidance.

Although live working should be avoided where possible, GS38 becomes essential when it cannot be. If the power must stay on, your safety procedures and your tools need to be watertight.

Always test your tester first (using a proving unit), then test the circuit, and then test the tester again. This three-step process confirms your device is functional throughout.

Look for frayed wires, cracked insulation, and loose connections. Just because a tester worked yesterday doesn’t mean it’s safe today.

Never rely on a neon screwdriver. Don’t use damaged or DIY leads. And never assume a circuit is dead without testing that’s how accidents happen.

Understanding GS38 isn’t just about reading a guide. Electricians must be trained and competent to recognise the risks and apply safe testing methods in practice.

Incorporate regular inspection of test equipment into your job routine. Many organisations include it in tool sign-out procedures or toolbox talks for good reason.

Although GS38 itself doesn’t require formal documentation, your electrical safety procedures including risk assessments and method statements should clearly reflect GS38 principles.

GS38 vs Other Electrical Safety Standards

BS7671 covers how electrical installations are designed and installed, while GS38 zeroes in on the safe use of test instruments. They complement one another but serve different purposes.

The Electricity at Work Regulations 1989, made under the Health and Safety at Work Act, are the legal framework. GS38 provides the practical interpretation of how to stay compliant with those laws.

Even if a manufacturer says their leads are safe, if they don’t meet GS38 criteria (like the 4mm rule), you’re still better off using something that does. Manufacturer claims aren’t always aligned with UK safety standards.

GS38 isn’t just another set of rules buried in a dusty folder. It’s a practical, safety-focused guide that exists because real people have suffered real harm when testing equipment wasn’t up to scratch.

Whether you’re a seasoned professional or a trainee just starting out, working to GS38 standards helps protect not just you, but also the people and properties around you. When electricity is involved, there’s no margin for guesswork, and GS38 helps ensure there doesn’t have to be.

Guide to GS38: Safe Use of Electrical Test Equipment

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