In applications such as sound reinforcement for a concert, however, it is difficult to ensure all equipment shares a common ground reference.
[1] Professional audio equipment intended for use with balanced lines may have a ground lift switch for the cable shield.
The switch disconnects pin 1 on the XLR jack, which is connected to the braid or foil shield in the cable and acts as the ground point of the circuit.
Removal of the safety ground connection on equipment can expose users to an increased danger of electric shock and may contradict wiring regulations.
Many other musicians have experienced electric shock due to ungrounded or improperly grounded equipment with less severe consequences.