When dielectric tests are carried out on cables or at fault location with high direct voltage, the circuit under test is charged due to its own capacity and stores a dangerous amount of energy; this energy can be calculated by the following formula: W = ½ x CV2

Once the test is finished, and before the operator can disconnect, it is necessary to discharge that stored energy preferably in a buffered form and once the discharge has been carried out it is necessary to ground the circuit using the earth rod, it must remain connected until all the disconnection procedures of the test equipment is completed.