Proving Units (28 Products)

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  1. Martindale PD240 pocket Sized Proving Unit - Kit All Martindale Products
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    Martindale PD240 pocket Sized Proving Unit for use with Voltage Indicators
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    • Maximum output current of 2mA
    • Maximum output voltage of 240V
    • Compact body made from flame-retardant ABS for safety
    102 Reward Points
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    SKU: MARPD240
  2. Martindale PD440 440V Proving Unit kit All Martindale Products
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    Martindale PD440 440V Proving Unit
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    • Works with products from other manufacturers
    • Checks for all safety regulations
    • Requires six 1.5 V batteries.
    146 Reward Points
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    SKU: MARPD440
  3. Martindale PD690 Proving Unit - Kit All Martindale Products
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    Martindale PD690 Proving Unit for use with Voltage Indicators
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    156 Reward Points
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    SKU: MARPD690
  4. Martindale PD700 50V and 700V high Current Indication Proving Unit All Martindale Products
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    Martindale PD700 Proving Unit
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    • Can be used with two pole voltage testers
    • Used with LED and LCD indications
    • Checks for full safety compliance
    176 Reward Points
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    SKU: MARPD700
  5. Martindale PD440S 440V Proving Unit - Kit All Martindale Products
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    Martindale PD440S 440V Proving Unit
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    £114.00 £95.00
    • Prove multimeters, voltage indicators, Drummond test lamps and two-pole testers
    • Lightweight, compact and rugged with a magnetic hanger
    • Long battery life with Auto Power Off and a low battery indicator
    190 Reward Points
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    SKU: MARPD440S
  6. Martindale PD430 50V & 440V Proving Unit - Kit All Martindale Products
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    Martindale PD430 50V and 440V Proving Unit
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    • Compact and portable yet durable and sturdy
    • Capable of both low and high checks
    • Easy to understand LED indication system
    190 Reward Points
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    SKU: MARPD430
  7. Martindale PD690S 690V Proving Unit All Martindale Products
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    Martindale PD690S 690V Proving Unit
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    £118.80 £99.00
    • Single voltage output: 690V AC
    • Applies the full voltage upon contact with the instrument-under-test
    • Prove multimeters, voltage indicators, Drummond test lamps and two-pole testers
    198 Reward Points
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    SKU: MARPD690S
  8. Martindale PD710 700V DC Proving Unit All Martindale Products
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    Martindale PD710 700V DC Proving Unit
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    • DC proving unit
    • Generates 700V
    • LED indicators
    200 Reward Points
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    SKU: MARPD710
  9. Martindale PD440SX 440V Proving Unit with CALCHECK - With Accessories All Martindale Products
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    Martindale PD440SX 440V Proving Unit with CALCHECK
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    £138.00 £115.00
    • Stepped voltages for checking two-pole voltage testers for calibration issues
    • CALCHECK: verify insulation and low-resistance ranges on 18th Edition multifunction testers
    • Prove multimeters, voltage indicators, two-pole voltage testers and Drummond test lamps
    230 Reward Points
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    SKU: MARPD440SX
  10. Martindale PD690SX 690V Proving Unit with CALCHECK - With Accessories All Martindale Products
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    Martindale PD690SX 690V Proving Unit with CALCHECK
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    £142.80 £119.00
    • CALCHECK: verify the insulation and low-resistance ranges on 18th Edition multifunction testers
    • Stepped voltages correspond to the LED thresholds of two-pole testers
    • Check 18th Edition multifunction testers and voltage testers for calibration faults
    238 Reward Points
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    SKU: MARPD690SX
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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 time 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 afterwards.

Proving units come in many different forms in order to accommodate for 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 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 compromisation of measurement accuracy. Other factors such as knocks and bumps, dust, water and other forms of natural contaminants can also effect the accuracy of a tester over a time period 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 - simply give us a call on the numbers at the top of this page and we'll help you out choosing the right proving unit for use with your voltage tester.

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