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 PD440SX 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.
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.