Regarding emergency systems, which of the following statements is true?

The statement regarding batteries maintaining the total lamp load at a voltage of at least 87 ½% is correct because emergency systems are designed to provide reliable power during a failure of the primary electrical supply. This voltage level is critical as it ensures that the emergency lighting operates effectively, providing adequate illumination to facilitate safe egress and operation during a power outage.

Maintaining the voltage at this level allows the emergency lamps to function properly and fulfill their safety role. If the voltage drops below this threshold, the effectiveness of the emergency lighting could be compromised, potentially leading to dangerous situations in case of an emergency.

In contrast to this, one might consider that the capacity for batteries to maintain only 70% of the lamp load would not provide sufficient illumination for safe egress. Similarly, while branch circuits could theoretically be part of a multiwire circuit, safety codes often dictate the separation of emergency circuits to prevent failures in one from impacting the other. Finally, emergency systems do require appropriate overcurrent protection to ensure they operate safely without risk of electrical faults or fires during emergencies.