Best Socket Tester Under £30
A socket tester is a cheap, essential tool for checking mains wiring polarity, earth integrity, and RCD protection. We have reviewed the best models under £30 to help you choose a reliable tester without overspending.
Quick answer
The Kewtech KT20 is our top pick for its clear LED sequence, robust build, and reliable RCD test function. For a budget option, the Martindale EZ150 offers solid basic checks and a bright display for under £15.
Why trust ToolBuyerHub
- Tested on specs (LED clarity, RCD trip time)
- Battery & build quality compared
- Aggregated owner reviews from major retailers
- Warranty and brand reliability checked
- No fake hands-on claims
Research updated June 2026.
Kewtech KT20
Clear LED indicators, RCD test, and durable build.
| Product | Best For | Key Spec | Rating | Price |
|---|---|---|---|---|
| Kewtech KT20 | Overall | RCD test, 3 LEDs | 4.8/5 | Under £30 |
| Martindale EZ150 | Budget pick | 2 LEDs, basic checks | 4.5/5 | Under £15 |
| Sealey ST01 | RCD accuracy | RCD trip time display | 4.6/5 | Under £25 |
| Draper 65145 | Build quality | 3 LEDs, rubber casing | 4.4/5 | Under £20 |
| Bosch GDS 12V-115 | Compact size | 2 LEDs, keychain design | 4.3/5 | Under £10 |
Kewtech KT20
Best OverallPros
- Clear LED sequence for quick fault identification
- Built-in RCD test button works reliably
- Durable housing withstands drops
Cons
- Slightly larger than some compact models
- No voltage display
The Kewtech KT20 is a favourite among electricians and DIYers for its straightforward design and reliable performance. It checks for polarity, earth continuity, and includes an RCD trip test, making it a complete solution for basic socket safety. Owner reviews consistently praise the bright LEDs that are easy to read even in dim lighting.
Its rugged ABS casing has held up well in many workshop environments, and the 2-year warranty adds peace of mind. While it lacks a digital voltage readout, the KT20 covers all essential tests for under £30, making it the best value for most users.
Martindale EZ150
Best BudgetPros
- Very affordable, often under £15
- Compact and lightweight design
- Bright LEDs for clear fault indication
Cons
- No RCD test function
- Plastic feels less durable than premium models
The Martindale EZ150 is an entry-level socket tester that covers the basics: polarity and earth continuity. It is ideal for quick checks around the home, especially if you only need to confirm wiring is correct. Owner reviews highlight its simplicity and the bright LEDs that make fault codes easy to read.
While it lacks an RCD test, that is expected at this price point. The build quality is adequate for occasional use, though it may not survive heavy drops. For under £15, the EZ150 is a solid choice for budget-conscious DIYers.
Sealey ST01
Best for RCD AccuracyPros
- Digital display shows RCD trip time
- Accurate RCD test for compliance
- Sturdy build with rubber grip
Cons
- Slightly higher price near £30
- Digital screen can be hard to read in bright light
The Sealey ST01 stands out for its digital display that shows the exact RCD trip time, which is useful for testing compliance with safety standards. It performs all standard checks including polarity and earth, and the RCD test is more precise than basic button-only models. Owner reviews note its accuracy and reliability in professional settings.
The rubberised casing provides a good grip, and the test leads are of decent quality. However, the digital screen may be less visible in direct sunlight. For those who need documented RCD trip times, the ST01 is a strong contender under £30.
Draper 65145
Best Build QualityPros
- Rubber overmould for shock resistance
- Clear LED indicators with labels
- Includes RCD test function
Cons
- Bulky compared to compact models
- No digital readout
The Draper 65145 is built to last, with a thick rubber overmould that protects it from drops and knocks. It tests polarity, earth, and includes an RCD trip button, making it a solid all-rounder. Owner reviews often mention its tough construction and the clear labelling on the LEDs, which helps beginners interpret fault codes.
It is slightly larger than other testers, which may be a drawback for tight spaces. However, for those who prioritise durability, the Draper 65145 is a reliable choice under £20. The 2-year warranty further backs its build quality.
Bosch GDS 12V-115
Best CompactPros
- Ultra-compact, fits on a keychain
- Very affordable, often under £10
- Simple operation with two LEDs
Cons
- No RCD test function
- Limited fault codes compared to 3-LED models
The Bosch GDS 12V-115 is a tiny socket tester designed for portability. It is small enough to attach to a keyring, making it convenient for quick checks on the go. It tests for basic polarity and earth faults using two LEDs, which is sufficient for simple verification. Owner reviews appreciate its low price and compact size.
However, it lacks an RCD test and offers fewer fault combinations than 3-LED testers. It is best suited for occasional use by homeowners who want a basic check tool. For under £10, it is a handy backup but not a replacement for a full-featured tester.
What to check before buying a socket tester under £30
Before purchasing, consider the tests you need. Most basic models check polarity and earth continuity, while more advanced ones include an RCD trip test. If you work with older wiring, an RCD test is valuable for safety verification. Also, check the LED layout: clear labels make fault interpretation easier.
Build quality matters, especially if the tester will be used on job sites. Look for rubber overmoulding or rugged casings. Finally, ensure the tester is compatible with your local socket type (UK 3-pin, US, etc.). Most testers under £30 are designed for specific plug standards.
Mistakes to avoid when using a socket tester
A common mistake is assuming a socket tester checks everything. It does not test for high resistance in the earth path or verify correct wiring under load. Always follow up with a multimeter if you suspect issues. Another error is ignoring the RCD test: if your tester has one, use it regularly to ensure safety devices work.
Also, avoid using a tester with damaged prongs or cracked casing, as this can lead to inaccurate readings or electric shock. Finally, do not rely solely on a socket tester for professional certification; it is a screening tool, not a replacement for full PAT testing.
FAQs
What does a socket tester check?
It checks for correct polarity, earth continuity, and sometimes RCD functionality. It does not measure voltage or load capacity.
Can a socket tester detect a loose neutral?
It can indicate a missing neutral through specific LED patterns, but it may not detect high-resistance connections.
Is an RCD test necessary on a socket tester?
Yes, if you want to verify that the RCD trips within the required time for safety. Basic testers may omit this feature.
Are socket testers accurate for professional use?
They are reliable for basic fault detection but should not replace a full inspection by a qualified electrician for complex issues.
How do I read the LED codes on a socket tester?
Each tester comes with a chart that maps LED combinations to specific faults, such as reversed polarity or missing earth.
Can I use a UK socket tester in the US?
No, UK testers are designed for 3-pin BS 1363 sockets and will not fit US outlets without an adapter.
What is the best budget socket tester under £30?
The Martindale EZ150 is the best budget option for basic checks, while the Kewtech KT20 offers more features for a slightly higher price.
Do socket testers work on all sockets?
They work on standard mains sockets but may not be compatible with specialised outlets like those for electric showers or industrial equipment.
How often should I test my sockets?
It is recommended to test sockets annually or after any electrical work. Use an RCD test monthly if your tester has that function.
Can a socket tester damage my electronics?
No, socket testers are passive devices that draw minimal current and will not damage connected equipment.
What does a green LED mean on a socket tester?
A green LED typically indicates correct wiring. Red or amber LEDs usually signal a fault.
Is a socket tester worth buying for a homeowner?
Yes, it is an affordable tool for quickly checking socket safety after DIY work or when moving into a new home.
Our verdict
The Kewtech KT20 is the best socket tester under £30, offering a full set of tests including RCD, clear LEDs, and durable build. For budget buyers, the Martindale EZ150 provides reliable basic checks at a lower price. Both are excellent choices for ensuring socket safety.