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Martindale PD440SX Proving Unit with CALCHECK

Original price was: £135.00.Current price is: £83.82. Inc VAT: £100.58

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    Martindale PD440SX Proving Unit with CALCHECK

    The Martindale PD440SX Proving Unit with CALCHECK has all the capabilities of the standard PD440S proving unit plus a unique CALCHECK feature for use with installation testers and 4 stepped voltage thresholds matched to common two pole tester thresholds.

    Safe electrical working requires the use of a voltage indicator that has been proven with a suitable proving device before and after use to ensure the instrument is working correctly in accordance with the Electricity at Work Regulations.

    The CALCHECK feature makes it easy to verify the insulation and low resistance ranges on 18th Edition multifunction instruments and single function insulation testers on-site, making it ideal for identifying potential calibration issues with a multifunction tester prior to certifying a new wiring installation or carrying out a condition report. It’s also a valuable procedure recognised by electrical contractor assessment bodies.

    It’s easy to keep a record of periodic CALCHECK results and equipment serial numbers for assessments using the form in the user guide or downloading copies from this page.  The individual reference resistance test pads with nominal values of 0.5Ωand 1.0Ω for continuity measurements and 0.5MΩ and 1.0MΩ for insulation resistance make it simple to check and identify calibration drift and remain confident in your test results wherever you are working.

    The proving unit output voltages are stepped with individual LED indicators for each voltage threshold from 50V to 440V matched to common two pole tester thresholds, ideal for identifying potential voltage tester calibration issues. On contact, the proving unit outputs the highest voltage first instantaneously checking all LEDs up to 440V and proving the tester for safe isolation use, it then steps down through each level automatically. At the end of the proving test, a low resistance appears across the terminals to verify the continuity function of two pole testers.

    It’s good practice to match the output voltage of the proving unit with the voltage range of the instrument to be proved. The new S and SX Series simplify matching devices as they are colour coded with Martindale voltage indicators.


    Output voltage440/230/100/50V nominal
    Output frequency50Hz nominal
    Output loadingSee datasheet
    CALCHECK insulation test resistance0.5MΩ (max test voltage 1kV)
    1.0MΩ (max test voltage 1kV)
    CALCHECK continuity test resistance0.5Ω (max test current 200mA)
    1.0Ω (max test current 200mA)
    Temperature (Operating & Storage)-10°C to 40°C
    Humidity (Operating & Storage)max. 70% R.H.
    Altitudeup to 2000m
    Pollution Degree2
    Power6 x 1.5V, AA alkaline batteries (IEC LR6, NEDA 15A)
    Dimensions150 x 80 x 35mm
    Weight350g approx. with batteries
    • Safely proves the operation of voltage indicators and test lamps up to 440V
    • Unique CALCHECK function for multifunction installation tests
    • Individual LED indicators matched to voltage indicator thresholds
    • Long battery life with low battery indicator
    • Includes MAG3 high strength magnetic hanger
    • Colour coded for voltage output
    • Martindale PD440SX 690V Proving Unit with CALCHECK
    • Martindale MG3 Magnetic Hanger
    • 6 x 1.5V AA Alkaline Batteries
    • Instruction Manual