Proving Units

An essential accompaniment to a voltage tester, proving units verify that the tester remains accurate both before and after testing. Both the NICEIC and NAPIT strongly recommend using these regularly when testing. Read More about Proving Units
  1. Kewtech KTP1 Proving Unit for Non-contact Voltage Testers
    Kewtech logo
    Lead Time: 1-2 Weeks
    Kewtech KTP1 Proving Unit for Non-contact Voltage Testers
    (no reviews)
    £63.59 £52.99
    • Test the functionality of non-contact voltage testers before and after use
    • Indicates functionality via a visual LED alert
    • Rugged design, drop tested from 1m
    52 Reward Points
    Price Match Guarantee
    KEWKTP1
  2. DiLog PU690 690V AC Proving Unit
    DiLog logo
    Only 1 In Stock
    DiLog PU690 690V AC Proving Unit
    (no reviews)
    £75.60 £63.00
    • Compact and lightweight
    • Suitable for proving high and low impedance instruments
    • Inbuilt 200kΩ load limits the current to 3.5mA at 690V
    63 Reward Points
    Price Match Guarantee
    PU690
  3. Martindale PD240 Pocket Sized Proving Unit
    Martindale logo
    In Stock
    Martindale PD240 Pocket Sized Proving Unit
    (1)
    £77.94 £64.95
    • Maximum output current of 2mA
    • Maximum output voltage of 240V
    • Compact body made from flame-retardant ABS for safety
    64 Reward Points
    Price Match Guarantee
    MARPD240
  4. Kewtech KEWPROVE3 Proving Unit
    Kewtech logo
    In Stock
    Kewtech KEWPROVE3 Proving Unit
    (3)
    £80.40 £67.00
    • Simple Design
    • Robust Casing
    • Magnet within the base
    67 Reward Points
    Price Match Guarantee
    KEWCB2
  5. Socket & See SP200 Professional Proving Unit
    Socket and See logo
    2 In Stock
    Socket & See SP200 Professional Proving Unit
    (2)
    £100.80 £84.00
    • Step voltage indication
    • First proving unit to generate an AC voltage waveform
    • Compact design
    84 Reward Points
    Price Match Guarantee
    SP200
  6. Martindale PD230SRD – 230V AC/DC Proving Unit with 3 Ranges
    Martindale logo
    Martindale PD230SRD – 230V AC/DC Proving Unit with 3 Ranges
    (no reviews)
    £100.80 £84.00
    • 3 ranges
    • Switchable AC / DC output mode
    • Suitable for use with voltage indicators up to 230V
    84 Reward Points
    Price Match Guarantee
    MARPD230SRD
  7. Megger MPU690 690v Proving Unit
    Megger logo
    In Stock
    Megger MPU690 690v Proving Unit
    (4)
    £102.00 £85.00
    • 5 stepped nominal output voltages
    • Automatic operation
    • High output power suitable for test lamps
    85 Reward Points
    Price Match Guarantee
    MPU690
  8. Martindale PD440S 440V Proving Unit
    Martindale logo
    In Stock
    Martindale PD440S 440V Proving Unit
    (no reviews)
    £106.80 £89.00
    • Auto Power Off
    • Lightweight, compact, and rugged 
    • Long battery life
    • Low battery indicator
    89 Reward Points
    Price Match Guarantee
    MARPD440S
  9. Kane PU690V 690V AC Proving Unit
    Kane logo
    Kane PU690V 690V AC Proving Unit
    (no reviews)
    £112.44 £93.70
    • Compact and lightweight voltage-proving unit
    • AC output up to 690V
    • High- and low-Z impedance compatibility
    93 Reward Points
    Price Match Guarantee
    KANE-PU690V
  10. Martindale PD690S 690V Proving Unit
    Martindale logo
    In Stock
    Martindale PD690S 690V Proving Unit
    (no reviews)
    £112.80 £94.00
    • Single voltage output: 690V AC
    • Applies full voltage upon contact
    • Auto Power Off function
    • Long battery life
    94 Reward Points
    Price Match Guarantee
    MARPD690S
  11. Socket & See SP400 Proving Unit
    Socket and See logo
    2 In Stock
    Socket & See SP400 Proving Unit
    (no reviews)
    £121.20 £101.00
    • Verify the functionality of multimeters, two-pole voltage indicators and non-contact voltage detectors
    • Intelligent voltage ramp: 50V, 100V, 230V, 400V and 690V
    • Able to synthesise tests at an AC mains supply frequency
    101 Reward Points
    Price Match Guarantee
    SP400
  12. Martindale PD440SX 440V Proving Unit with CALCHECK
    Martindale logo
    Only 1 In Stock
    Martindale PD440SX 440V Proving Unit with CALCHECK
    (no reviews)
    £123.60 £103.00
    • Stepped voltages
    • CALCHECK
    • Auto Power Off function
    • Low battery indicator
    103 Reward Points
    Price Match Guarantee
    MARPD440SX
  13. Martindale PD690SX 690V Proving Unit with CALCHECK
    Martindale logo
    3 In Stock
    Martindale PD690SX 690V Proving Unit with CALCHECK
    (no reviews)
    £126.00 £105.00
    • CALCHECK
    • Low battery indicator
    • Long battery life
    • Auto Power Off function
    105 Reward Points
    Price Match Guarantee
    MARPD690SX
  14. DiLog DLPK6780 CombiVolt 1 & PU690V Proving Unit Kit
    DiLog logo
    In Stock
    DiLog DLPK6780 CombiVolt 1 & PU690V Proving Unit Kit
    (no reviews)
    £130.80 £109.00
    • Bespoke pouch means the kit can be carried on the user’s person
    • Three-in-one voltage, continuity and phase tester
    • Proving unit for maintaining compliance with safe isolation procedures

     

    109 Reward Points
    Price Match Guarantee
    DLPK6780
  15. Martindale PD440SRD – 440V AC/DC Proving Unit with 4 Ranges
    Martindale logo
    Lead Time: 1-2 Weeks
    Martindale PD440SRD – 440V AC/DC Proving Unit with 4 Ranges
    (no reviews)
    £133.20 £111.00
    • 4 ranges
    • Switchable AC / DC output mode
    • Suitable for use with voltage indicators up to 440V
    111 Reward Points
    Price Match Guarantee
    MARPD440SRD
  16. Martindale PD440SRDX – 440V AC/DC Proving Unit with 4 Ranges & CALCHECK
    Martindale logo
    Martindale PD440SRDX – 440V AC/DC Proving Unit with 4 Ranges & CALCHECK
    (no reviews)
    £138.00 £115.00
    • CALCHECK
    • 4 ranges
    • Compatible with S-series magnetic hanger
    115 Reward Points
    Price Match Guarantee
    MARPD440SRDX
  17. DiLog DLPK6790 CombiVolt 2 & PU690V Proving Unit Kit
    DiLog logo
    3 In Stock
    DiLog DLPK6790 CombiVolt 2 & PU690V Proving Unit Kit
    (no reviews)
    £141.60 £118.00
    • Bespoke pouch means the kit can be carried on the user’s person
    • Three-in-one voltage, continuity and phase indicator
    • Proving unit suitable for testing high and low impedance instruments
    118 Reward Points
    Price Match Guarantee
    DLPK6790
  18. Martindale PD690SRD – 690V AC/DC Proving Unit with 5 Ranges
    Martindale logo
    Lead Time: 1-6 Days
    Martindale PD690SRD – 690V AC/DC Proving Unit with 5 Ranges
    (no reviews)
    £142.80 £119.00
    • 5 ranges
    • Switchable AC / DC output mode
    • Suitable for use with voltage indicators up to 690V
    119 Reward Points
    Price Match Guarantee
    MARPD690SRD
  19. Martindale PD690S-C 690V AC Proving Unit & TC71 Carry Case
    Martindale logo
    Lead Time: 1-6 Days
    Martindale PD690S-C 690V AC Proving Unit & TC71 Carry Case
    (no reviews)
    £150.00 £125.00
    • Low-profile, durable proving unit
    • 690V test voltage
    • Heavy denier nylon case with a shoulder strap and clear front pocket
    125 Reward Points
    Price Match Guarantee
    MARPD690S-C
  20. Fluke PRV240FS Proving Unit
    Fluke logo
    In Stock
    Fluke PRV240FS Proving Unit
    (1)
    £152.28 £126.90
    • Performs TBT tests, providing a known voltage against which Fluke’s T6 Electrical Testers, FieldSense measurement function, and other high impedance products can be checked
    • Simple-to-use single switch operation system with LED lights for functionality indication
    • Protects the user from risks of shock and arc flash
    126 Reward Points
    Price Match Guarantee
    4910310
  21. Fluke PRV240 Proving Unit
    Fluke logo
    4 In Stock
    Fluke PRV240 Proving Unit
    (no reviews)
    £162.00 £135.00
    • Generates both AC/DC voltage to 240V
    • LED indicator
    • Ideal for use with clamp meters and multimeters, as well as two-pole voltage testers
    135 Reward Points
    Price Match Guarantee
    4566209
  22. KANE-VCT KIT Voltage & Continuity Tester with 690 volt AC Proving Unit
    Kane logo
    Only 1 In Stock
    KANE-VCT KIT Voltage & Continuity Tester with 690 volt AC Proving Unit
    (no reviews)
    £168.00 £140.00
    • KANE-VCT Voltage Tester
    • KANE-PU690V Proving Unit
    • Kit Carry Pouch
    • Batteries
    140 Reward Points
    Price Match Guarantee
    KANE-VCTKIT
  23. Martindale VIPD138-S Voltage Indicator & Proving Unit Kit
    Martindale logo
    In Stock
    Martindale VIPD138-S Voltage Indicator & Proving Unit Kit
    (no reviews)
    £178.80 £149.00
    • PD440S: 440V industry-leading proving unit
    • VI13800 Voltage tester range: 50V to 600V AC/DC
    • TC71 Combination Carry Case
    149 Reward Points
    Price Match Guarantee
    MARVIPD138-S
  24. Kewtech KEWISO3 Safety Isolation Kit - Voltage Tester, Proving Unit, MCB Lockout & Case
    Kewtech logo
    2 In Stock
    Kewtech KEWISO3 Safety Isolation Kit - Voltage Tester, Proving Unit, MCB Lockout & Case
    (no reviews)
    £190.80 £159.00
    • Ultimate solution for safety isolation procedures
    • The KEWLOK padlock small size fits perfectly in pockets or tool kits
    • KEWPROVE 3 works directly with the KT1795
    159 Reward Points
    Price Match Guarantee
    KEWISO3

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About Proving Units

Proving units are portable, lightweight calibration tools that are designed for use with two-pole voltage testers. The function of a proving unit is to evaluate that the internal components of the voltage tester are working correctly and that measurement accuracy is maintained.

Although regular, formal calibration is still a priority, using a proving unit in combination with a two-pole voltage tester is an ideal way to ensure measurement accuracy is maintained in the period between official calibration procedures. Most manufacturers recommend that a proving unit is used both before and after testing using a voltage tester; this way, damage to the machine during transportation can be detected before testing, or damage to the machine during the actual testing procedure can be detected afterward.

Proving units come in many different forms to accommodate the vast voltage range spectrum that can be applied to two-pole testers. Some proving units might be designed for measuring low voltage testers, while others may be designed for higher voltage. Some may also be suitable for both low and high-voltage testers, measuring across the entire spectrum. A common function found on these units is ramp voltage. The proving unit applies several different voltages to the two-pole voltage tester that is inserted into ports on the proving unit and the device measures whether everything is working correctly with the applied voltage. The indicators are usually expressed via the use of LED lights and if everything is correct the LED light indicators should tell you that this is the case.

Stepped voltages again vary depending on the proving unit being used.

Using a proving unit to maintain accuracy is particularly important as frequent usage of a tester can result in the compromise of measurement accuracy. Other factors such as knocks and bumps, dust, water, and other forms of natural contaminants can also affect the accuracy of a tester over time and if these inaccuracies go unnoticed it can make the tester unsafe and also produce incorrect readings when used on a system.

Our range of proving units come from many different manufacturers, including Kewtech, Martindale, Megger, Seaward, and Socket and See. As mentioned earlier their capabilities vary from tester to tester, so knowing which unit you need before making a purchase is highly recommended. If you're confused about which unit you need we're more than happy to help you make a decision - get in touch and we'll help you out choosing the right proving unit for use with your voltage tester.

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