Best Socket Tester for Fault Finding
Finding a wiring fault in a mains socket can be dangerous without the right tool. A reliable socket tester quickly identifies missing earths, reversed polarity, and other common issues, making it essential for electricians and DIYers.
Quick answer
The best socket tester for fault finding is the Klein Tools RT250 for its clear GFCI testing and robust build. For a budget option, the Sealey VS820 offers reliable basic fault detection at a lower price.
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Research updated June 2026.
Klein Tools RT250
Excellent GFCI trip testing and clear LED indication for fast fault identification.
| Product | Best For | Key Spec | Rating | Price |
|---|---|---|---|---|
| Klein Tools RT250 | Overall / GFCI testing | GFCI trip, 6 fault codes | 4.7/5 | Mid |
| Sealey VS820 | Budget / Basic use | 3 LED indicators | 4.3/5 | Low |
| Bosch GIT 120 | Professional / RCD test | RCD test, voltage display | 4.5/5 | Mid |
| Draper 230V Socket Tester | DIY / Simple checks | 3 LED, no GFCI | 4.1/5 | Low |
| Kewtech KEW 64TR | Comprehensive fault finding | 7 fault codes, RCD test | 4.6/5 | High |
Klein Tools RT250
Best OverallPros
- Built-in GFCI trip test
- Durable construction
- Clear LED fault codes
Cons
- No voltage display
- Higher price than basic models
The Klein Tools RT250 is a professional-grade socket tester that excels in fault finding. It detects six common wiring faults including open ground, reverse polarity, and open neutral. The integrated GFCI test button allows you to verify ground fault protection on circuits.
Owner reviews highlight its rugged build and easy-to-read LED pattern chart on the device. It is a reliable choice for electricians who need a quick and accurate diagnosis without extra features like voltage readouts.
Sealey VS820
Best BudgetPros
- Very affordable
- Simple to use
- Compact size
Cons
- No GFCI test
- Limited fault detection
The Sealey VS820 is a straightforward, no-frills socket tester ideal for basic fault finding. It uses three LEDs to indicate correct wiring or common faults like missing earth and reversed polarity. It is a good entry-level tool for homeowners.
Aggregated reviews note its low price and simplicity as key positives, but some users wish it could test GFCI outlets. It is best for quick checks on standard sockets where advanced features are not needed.
Bosch GIT 120
Best for ProfessionalsPros
- Digital voltage display
- RCD trip test
- Durable rubberized body
Cons
- Higher price point
- Bulkier than basic testers
The Bosch GIT 120 is a more advanced socket tester that adds a digital voltage readout to standard fault detection. It can test RCDs (residual current devices) and display the actual voltage on the circuit. This makes it a valuable tool for professional electricians.
Owner feedback praises its accuracy and build quality, though some note it is larger than simpler models. The digital display helps confirm voltage levels, which is useful for diagnosing intermittent issues.
Draper 230V Socket Tester
Best for DIYPros
- Very low cost
- Simple LED chart
- Lightweight
Cons
- No GFCI/RCD test
- Basic fault detection only
The Draper 230V Socket Tester is a basic tool for DIYers who need to check if a socket is wired correctly. It uses three LEDs to indicate correct wiring or common faults like live/neutral reverse. It is a simple, no-fuss device for occasional use.
Reviews mention its low price and ease of use as main benefits. However, it lacks advanced features like GFCI testing, so it is not suitable for comprehensive fault finding on protected circuits.
Kewtech KEW 64TR
Best ComprehensivePros
- Detects 7 fault conditions
- RCD trip test included
- Professional build quality
Cons
- Premium price
- No digital display
The Kewtech KEW 64TR is a comprehensive socket tester designed for professional fault finding. It can detect seven different wiring faults, including complex issues like phase and earth reversed. The built-in RCD test function adds to its versatility.
User reviews consistently praise its reliability and the clarity of its fault code chart. It is a premium tool that justifies its cost for electricians who need to diagnose a wide range of socket problems accurately.
What to check before buying a socket tester
Before purchasing a socket tester, consider the types of sockets you will be testing. Most testers work on standard 3-pin outlets, but some also support older or non-standard wiring. Check if the tester includes GFCI or RCD testing if you work on protected circuits.
Also look at the number of fault codes the device can identify. Basic models detect three to four faults, while advanced units can identify seven or more conditions. Build quality matters too, as a durable tester will survive drops on job sites.
Mistakes to avoid when using a socket tester
A common mistake is relying solely on a basic tester for comprehensive diagnostics. A simple three-LED tester may not detect all faults, such as a high-resistance ground. Always use a tester that matches the complexity of the job.
Another error is ignoring the GFCI test function. Many users skip this step, but it is vital for verifying safety on outlets in bathrooms and kitchens. Also, never assume a tester is accurate without consulting the fault code chart provided with the device.
FAQs
What is a socket tester used for?
A socket tester is used to quickly identify common wiring faults in mains electrical outlets, such as missing earths or reversed polarity.
Can a socket tester detect a loose neutral?
Yes, many socket testers can detect an open neutral, which is a common cause of intermittent power loss.
Do I need a GFCI test on a socket tester?
Yes, if you are testing outlets in wet areas like kitchens or bathrooms, a GFCI test is essential for safety.
Are cheap socket testers reliable?
Cheap testers are reliable for basic fault detection but may miss more complex issues like high resistance or faulty RCDs.
How do I read a socket tester?
Most testers use a combination of LED lights that correspond to a fault code chart printed on the device or included in the manual.
What does a green light on a socket tester mean?
A green light typically indicates correct wiring, but you should always check the specific LED pattern for your model.
Can a socket tester damage electronics?
No, socket testers are passive devices that only check wiring and do not send harmful signals to connected equipment.
What is the difference between RCD and GFCI?
RCD and GFCI are essentially the same safety device that cuts power when it detects a ground fault; the terms are used in different regions.
How often should I test my sockets?
It is good practice to test sockets annually or whenever you notice flickering lights or tripping breakers.
Can I use a socket tester on a 3-phase outlet?
No, standard socket testers are designed for single-phase residential outlets and should not be used on 3-phase systems.
Our verdict
For most users, the Klein Tools RT250 is the best socket tester for fault finding due to its reliable GFCI testing and durable build. If you are on a tight budget, the Sealey VS820 provides essential fault detection at a lower cost.