Final answer:
The statement is False; disconnect switches are not intended to open fault current but to de-energize circuits for safety. It is circuit breakers and fuses that are designed to interrupt excessive currents to prevent hazards.
Step-by-step explanation:
The statement that disconnect switches or breaker isolation switches are designed to open fault current is False. The purpose of disconnect switches is to safely de-energize circuits for maintenance or in emergency situations, not to interrupt fault current under normal operational conditions. For this reason, circuit breakers and fuses are used because they are specifically designed to interrupt excessive currents to prevent thermal hazards like fires. In contrast, large circuit breakers in power-distribution systems do address the challenge of interrupting high-voltage electricity and employ insulating gas and even use jets of gas to blow out sparks that may occur when trying to break the circuit.
An isolation transformer, on the other hand, provides electrical isolation and prevents shock by insulating the device being powered from the original source. Similarly, a ground fault interrupter (GFI) prevents shock by detecting the loss of current to unintended paths and is able to open the circuit quickly in the event of a fault. It is important to note that these devices are all part of larger systems designed to ensure electrical safety by preventing thermal and shock hazards.