What type of switch is depicted by the NEMA symbol at location II?

The type of switch indicated by the NEMA symbol at location II is correctly identified as a normally closed switch. A normally closed switch is designed to be in the 'on' position or conducting state when it is not being activated or engaged by an external force. This means the electrical circuit is completed until the switch is physically opened or toggled.

In practical applications, normally closed switches are often used in safety circuits or emergency stop functions, where it is crucial for the circuit to remain active until a specific action is taken to interrupt it. This functionality ensures that the system remains operational under normal conditions and can only be shut down when necessary, which is fundamental in various industrial and safety-related contexts.

The other options represent different switch configurations but do not match the characteristics of the normally closed switch. Normally open switches only allow current to pass when they are activated, while single-pole and double-throw designations refer to the switch's configuration rather than its default closed or open state. Understanding these distinctions is key to identifying switch types based on their NEMA symbols.