What primary role do junction boxes play in electrical systems?

Junction boxes play a critical role in electrical systems primarily by providing a secure and organized space for making splices or connecting conductors. These boxes serve several important functions: they protect conductor connections from damage, allow for easier access for maintenance and modifications, and help to contain any potential electrical hazards within the box itself. By housing these connections, junction boxes ensure that the electrical system can be safely expanded or modified without compromising the integrity of the wiring.

While other choices mention tasks related to electrical systems, they do not accurately represent the designated role of a junction box. For instance, housing circuit breakers pertains more to panelboards or subpanels rather than junction boxes, and storing tools is unrelated to any electrical function. Isolating power sources typically involves switches or disconnects, rather than junction boxes, which are specifically intended for splicing connections.