Martindale PD440SX
  • Martindale PD440SX
  • Martindale PD440SX
  • Martindale PD440SX

Martindale PD440SX Proving Unit

Martindale approved distributor and service centre.

Includes: MG3 magnetic hanger, 6 x 1.5V AA alkaline batteries and instruction manual.

Tax excluded
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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 Martindale 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.

Both the PD440SX and the PD690SX ramp output voltage down in a sequence lasting for a duration of 10s, before reducing output voltage to zero.

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.

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.


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 PD Comparison
PD690S PD440SX PD690SX
Maximum Voltage Output 690V AC 440V AC 690V AC.
LED Voltage Thresholds 690V 50V, 120V, 230V, 440V. 50V, 120V, 230V, 400V, 690V.
High Voltage LED Multiple. Multiple.
Low Battery LED
High/Low Z Compatible
CALCHECK Resistance Values
Colour Coded to Match Voltage Indicators
Suitable for Multimeters, voltage testers & Drummond test lamps. Multimeters, voltage testers & Drummond test lamps. Multimeters, voltage testers & Drummond test lamps.

Martindale PD440SX Specifications
Output voltage 440/230/100/50 V nominal.
Output frequency 50 Hz nominal.
Output loading See datasheet.
CALCHECK insulation test resistance 0.5 MΩ (max test voltage 1 kV)
1.0 MΩ (max test voltage 1 kV).
CALCHECK continuity test resistance 0.5 Ω (max test current 200 mA)
1.0 Ω (max test current 200 mA).
Temperature (Operating & Storage) -10°C to 40°C.
Humidity (Operating & Storage) max. 70% R.H.
Altitude up to 2000m.
Pollution Degree 2
Power 6 x 1.5 V, AA alkaline batteries (IEC LR6, NEDA 15A).
Dimensions 150 x 80 x 35 mm.
Weight 350g approx. with batteries.
Martindale PD440SX warranty Two-years.


Martindale PD690SX Datasheet

PDF Specifications of the Martindale PDS & PDSX Proving Units.

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