Martindale vt12 voltage tester and pd690 proving device martindale vt12pd the martindale vt12pd kit includes a vt12 voltage tester and a pd690 proving device which enables the user to comply with health and safety recommendations for safe working by proving the functionality of the voltage tester before and after usethe vt12 is a two pole voltage tester which complies with bs en61243 32010 and provides clear indication of ac and dc voltages from 12 to 690v it is durable enough for both d