Electrical Test Equipment

Socket and See Vehicle Mounted Proving Unit

The Socket & See VP400L Proving Unit provides a safe and reliable means of checking the correct functioning of Multimeters and two pole Voltage Indicators  before and after use as advised in the Working Practice for electricians. 

Additionally they have the capability of checking the operation of Non-contract voltage detectors.

VP400 is designed to be permanently mounted and powered from a 12V vechile supply.  The VP400 unit has a unique and logical safety function:  the test voltage generated is at 50Hz to synthesise a genuine test at AC mains supply frequency. So it will always read correctly when using the AC range of your Tester or Multimeter.

The VP400 will also test two-pole voltage tester that use small incandescent lamps to indicate that voltage is present. 


  • Intelligent voltage ramp for testing multimeters and Voltage Indicators
  • Generates from 50-690V with a true AC waveform output
  • Non-contract voltage indicator test feature
  • Powerful enough to light old filament style test lamps
  • Automatic operation and turn-off


Output voltage: 50 - 690V in five steps of 50V, 100V, 230V, 400V and 690V
Power supply: 12V Vehicle Supply
Operating conditions: -10 to +35c at 95% RH, non-condensing
Output frequency: 50Hz pseudo sine wave
Maximum Output power: 10W
Weight 346g
Dimensions: 130mm (W) x 68mm (H) x 48mm (D)
LVD: BSEN 61010-1 (2010)
EMC: 61326-1 (2006)

Electrical safety code of practice 2013

Managing electrical risks in the workplace

9.4 Test instruments

Testing equipment used for detecting an energised source should be checked to prove that it is functioning correctly immediately before and after the test has taken place. The standard test regime is to test a known source of energy, test the de-energised circuit for zero volts then test the known source again.

Part No. VP400L