Electrical equipment arranged in the roof of an electrically powered railway vehicle

The electric equipment (2) has an alternating current (AC) supply source (6) connected to an AC supply line (12). An AC circuit breaker (14) i.e. vacuum circuit breaker, is arranged on the line to isolate a high voltage equipment from the source when it is opened. A grounding disconnecting switch (20) is moved between opened and closed positions. A disconnecting device (28) is moved between a closed position in which current circulates on the line and an opened position in which a connection between the source and the breaker or the breaker and the high voltage equipment is interrupted.