The graphic shows a common type of panelboard with an integral main service disconnect. For this panelboard installation, there is a 3-wire service-entrance SEU conductor cable from the meter to the main panelboard. The cable has two ungrounded “hot” conductors and one bare, stranded, ungrounded “neutral” conductor. The bare, stranded, grounded “neutral” conductor connects to the neutral bus bar. The main service disconnect (the main disconnect breaker) is the master switch for the panelboard. It shuts off the power to everything downstream, including the hot bus bars and all breakers mounted to them. The MBJ connects the service neutral wiring to the grounding electrode conductor (GEC) and also to the service panelboard cabinet.