CK-Tools Socket Tester Review
The CK-Tools Socket Tester (model TST100) is a compact mains tester designed for quick polarity and earth checks on UK 3-pin sockets. This review covers its build, accuracy, and value compared to other basic electrical testers.
Quick answer
The CK-Tools TST100 is the best basic socket tester for electricians and DIYers who need a reliable, no-nonsense tool for verifying correct wiring on UK 13A sockets. Its clear LED display and robust build make it a top pick for daily use.
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Research updated June 2026.
CK-Tools TST100 Socket Tester
Reliable, clear LED indication for UK sockets.
Who is the CK-Tools Socket Tester for?
The CK-Tools TST100 is designed for electricians, maintenance engineers, and serious DIYers who need to verify the wiring of UK 13A sockets quickly. It is not a multifunction tester; it focuses on one job: checking for live, neutral, and earth connections and identifying common faults like reversed polarity or missing earth.
This tool is ideal for those who want a simple pass/fail indication without the complexity of a full multifunction installation tester. It is a common sight on tool belts for final checks after installing or repairing sockets.
Performance and Indication
The TST100 uses a three-LED system to indicate the wiring status. The back of the unit has a clear chart that maps the LED patterns to specific wiring conditions. This includes correct wiring, reversed live/neutral, reversed live/earth, missing earth, and missing neutral. Owner reviews on retailer sites consistently note that the LEDs are bright and easy to read, even in dimly lit areas like under a desk or in a cupboard.
The tester is rated for 230V AC 50Hz, matching the UK mains supply. It does not require batteries, as it draws power from the socket being tested. This is a significant advantage for reliability, as there is no risk of a flat battery rendering the tool useless.
Build Quality and Design
CK-Tools is known for producing robust professional tools, and the TST100 follows this tradition. The body is made from a tough, impact-resistant ABS plastic. The 3-pin plug is molded as part of the unit, meaning there are no cables to fray or break. The pins are solid brass and fit snugly into standard UK sockets without being too loose or too tight.
The unit is compact enough to fit in a shirt pocket or a small pouch on a tool belt. The label on the back is printed rather than a sticker, which means it will not peel off over time. This is a detail that professional users appreciate, as the fault code chart needs to remain legible.
Alternatives to the CK-Tools TST100
For users who need more advanced features, the Kewtech KTS1000 offers a similar form factor but with an additional RCD test button. This allows you to test the trip time of a Residual Current Device (RCD) from the socket itself, which the CK-Tools unit cannot do. The Kewtech model is more expensive but adds a critical safety function for professional periodic inspections.
Another alternative is the Martindale EZ65, which also provides socket testing and RCD testing. It is a well-regarded brand in the electrical testing world. For a basic, no-frills check, the CK-Tools TST100 remains the best value option.
Pros
- No batteries required
- Bright, clear LED indicators
- Rugged, professional build quality
- Compact and pocket-friendly
Cons
- No RCD test function
- Only for UK 3-pin sockets
FAQs
Does the CK-Tools socket tester work on US or EU sockets?
No, the TST100 is specifically designed for UK 3-pin sockets (BS 1363) and will not physically fit other plug types.
Does it require a battery?
No, it draws power directly from the socket being tested, so there are no batteries to replace.
What faults can it detect?
It can detect correct wiring, reversed live/neutral, reversed live/earth, missing earth, and missing neutral.
Is it suitable for professional electricians?
Yes, it is a standard tool for quick polarity checks, but professionals may also need a separate RCD tester for full certification.
How do I read the results?
The back of the unit has a clear chart showing the LED pattern for each wiring condition.
Is it safe to use?
Yes, it is fully insulated and designed to BS 1363 safety standards for UK mains voltage.
Can it test RCDs?
No, this model does not have an RCD test button. You would need a Kewtech KTS1000 for that function.
What is the warranty?
CK-Tools typically offers a 1-year warranty against manufacturing defects.
Is it better than a multimeter for socket testing?
For a simple pass/fail check, yes. A multimeter requires more skill to interpret readings for polarity.
Can it be used on extension leads?
Yes, it can be plugged into any standard UK 13A socket, including those on extension leads.
Our verdict
The CK-Tools TST100 is the best basic socket tester for reliable polarity checks on UK sockets. For professionals needing RCD testing, consider the Kewtech KTS1000 as an alternative.