Every service entering a building must have a means to disconnect all ungrounded conductors — and the exam tests where it goes, how many are permitted, and how recent editions tightened the rules.
The service disconnecting means is the switch or circuit breaker — or group of them — that allows all ungrounded service conductors to be isolated from the premises wiring at a single accessible location. It is the dividing line between the utility's side of the installation and everything an electrician is responsible for. Without a clearly identified, accessible disconnect, cutting power to a building in an emergency means working back through the meter or calling the utility — neither is acceptable under the NEC.
On the journeyman exam, service-disconnect questions cluster around three things: where the disconnect must be placed, how many separate disconnects are permitted, and how the rules have shifted in more recent NEC editions to address emergency access. Getting all three right is the difference between a half-credit answer and a full one.
Section 230.70(A) fixes two acceptable locations for the service disconnect: outside a building or structure, or inside the building at the nearest practicable point to where the service conductors enter. "Nearest practicable point" is not an invitation to run the conductors across the basement — inspectors look for the shortest reasonable path from the service entrance to the disconnect. The underlying policy is that anyone who needs to de-energize the building — a firefighter, a utility worker, or the homeowner — can reach the disconnect quickly without navigating through occupied spaces.
The disconnect must also be in a readily accessible location, meaning it can be reached quickly without climbing over obstacles or removing barriers. A disconnect locked inside a storage closet or installed behind a fixed shelf fails this test. Readily accessible is not the same as accessible — accessible allows removing a panel door or cover; readily accessible means you can get to it immediately.
Additional location restrictions in 230.70(A) keep the disconnect out of bathrooms — a specific prohibition the exam sometimes tests as a distractor choice.
For decades the NEC allowed a single service to be controlled by a group of up to six disconnects at one location. The idea — often called the "six operations of the hand" rule — is that opening no more than six switches or breakers can de-energize the entire service. Each disconnect controls its own set of ungrounded conductors, and together they cover the whole service. All six must be grouped at the same location, and each must be marked to identify the load it serves.
More recent NEC editions have moved away from the grouped-six approach for residential installations, pushing toward a single main disconnect. The 2023 edition, for example, added explicit requirements for one- and two-family dwellings that effectively require a single means of disconnection for those occupancies. Jurisdictions adopt NEC editions on their own schedule, so the applicable rule depends on which edition your state or municipality has enacted — but knowing that the trend is away from grouped disconnects is important context for any edition-neutral exam question.
The 2020 NEC added Section 230.85, which requires one- and two-family dwellings to have a readily accessible means of disconnect installed outside the building. The intent is straightforward: emergency responders arriving at a house fire need a way to cut power without entering the structure. This outdoor disconnect must be permanently marked to identify it as an emergency disconnect, and it must simultaneously disconnect all ungrounded conductors.
The exam may present 230.85 as a separate concept from the service disconnect at 230.70, and the key distinction is purpose: 230.70 governs the main disconnect that the electrician installs as part of the service, while 230.85 specifically addresses the outdoor, emergency-accessible location. In practice, a main service disconnect located outside the dwelling can satisfy both requirements at once — but the two sections have different triggering conditions and markings. Knowing the section numbers and the occupancy types each applies to puts you ahead on exam day.
| Requirement | Section | Key point |
|---|---|---|
| Disconnect location | 230.70(A) | Outside, or inside at nearest point of entry; not in bathrooms |
| Maximum number of disconnects | 230.71 | Not more than six at one location (long-standing rule) |
| Single disconnect (residential) | 230.71 (recent eds.) | More recent editions require a single disconnect for one- and two-family dwellings |
| Emergency disconnect | 230.85 (2020+) | Outdoors, marked, for one- and two-family; added in 2020 NEC |
The service disconnect is also the reference point for sizing. The disconnect rating must be at least equal to the calculated load it controls, and the equipment grounding and bonding requirements of Article 250 connect at the service disconnecting means enclosure. Exam questions often combine disconnect location with grounding and bonding in the same scenario — knowing where the disconnect sits helps you answer both parts.
Loomi turns NEC content into 9,000+ spaced-repetition exam questions built for the journeyman test. Reserve your founders' seat before launch.
Join the waitlist