To measure the electrostatic voltages generated on a person getting out of a car

1) Electrostatic voltmeter with analogue and/or serial data output, with ability to measure voltages to at least 20kV with a resolution of 50V or better, a leakage resistance 10¹⁴ ohms or greater at voltages over 10kV, an internal capacitance less than 10pF and a response time below 0.1s.

2) Signal recording equipment capable of storing data with time resolution of 0.1s or better

3) Springy or coiled HV lead with high quality insulation cover to connect the electrostatic voltmeter to the person. This needs to provide no noticeable impediment to personal movement in getting out of the car and no dragging over surfaces during such actions and providing a leakage resistance 10¹⁴ ohms or better at 10kV.

4) Sheet of good quality insulation to place on the ground at the point of contact of the feet with the ground and for standing after getting out of the car. This needs to provide 10¹⁴ ohms isolation at voltages up to 20kV.

5) For assessing the characteristics of the materials of the seating and the clothing:

The temperature and humidity in the car at the time of testing are to be measured - for example using a Whirling Hygrometer. Because the characteristics of materials can be strongly influenced by absorbed moisture the car, any alternative seating materials and all clothing worn shall be exposed to the test conditions for several hours before the start of testing.

For standardised studies measurements are to be made at 23C 50%RH and at 23C 12%RH. The test garments and the car shall be under these conditions for 24 hours before starting tests.

Place the electrostatic voltmeter on the other seat than that to be used for testing and link it to the signal recording equipment. Bond the earth connection of the voltmeter to the metal bodywork of the car. Link the HV connection from the electrostatic voltmeter to the tester - for example to a wristband or metal watch strap.

Place the sheet of good quality insulation on the ground at the point of contact and covering the position of standing after getting out of the car.

Perform a test action of getting out of the car to check that the HV connection lead moves freely and does not impede activity.

Switch on the electrostatic voltmeter and signal recording equipment and check operating satisfactorily. Record relevant test parameters and the date and time.

Perform at least 3 activities of getting out of the car in a normal manner from the selected seat with each set of test conditions. Leave the car without the body touching the metal bodywork and with the feet impacting squarely on the layer of insulation on the ground. Avoid any sliding or scuffing action of the feet on the insulation. After leaving the car stand still on the insulation for at least 5s to allow recording of the natural rate of voltage decay.

Where studies are made on a number of different seat fabrics and/or wearing various clothing the sequence of tests shall preferably start and finish with standard or reference combinations of materials. If significant changes are observed then additional tests shall be performed to establish if the changes are due to changes in ennvironmental conditions, transfer of fabric finish or other factors.

The following information shall be reported:

- peak and plateau values of body voltages observed shall be listed

- description of the make and model of the car and the seat used for testing

- the seat material

- the type and fabric of clothing worn (including component fibers and weave if possible)

- the charge decay times of seat area of clothing worn with open and earthed backing and of the car seat surface in situ (front and rear areas)

- the surface resistivity of the seat area of clothing worn and of the car seat surface in situ (front and rear areas)

- the temperature and humidity in the vehicle.

The performance with a particular set of test conditions shall be in terms of the highest value of the peak voltage value observed - not the average. If a larger number of tests are performed under particular test conditions, say at least 5, then it will also be appropriate to calculate the mean of the values observed and the standard deviation.

The description and type numbers of the instrumentation and the data recording equipment used shall be recorded together with the serial numbers and date of most recent calibration.