NEC · 230.70–230.71

Service Disconnecting Means (230.70)

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.

NEC 2017 2020 2023 Last updated 2026-06-27

What the service disconnect does

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.

Location requirements (230.70(A))

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.

The six-disconnect rule (230.71) and the single-disconnect trend

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.

Emergency disconnect (230.85) and exam angle

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.

Practice questions on this rule

Real journeyman-exam practice questions from Loomi's bank — answer first, then reveal the explanation.

Q1 NEC 230.72

Per 230.72(B), why must additional service disconnecting means for emergency or standby systems be installed remote from the normal service disconnects?

  1. A To keep emergency wiring shorter for reduced voltage drop
  2. B To satisfy the grouping requirement in 230.72(A) for all disconnects on the property
  3. C Because emergency disconnects require a different enclosure rating
  4. D To minimize the possibility of simultaneous interruption of supply
Show answer & explanation

Correct: D — To minimize the possibility of simultaneous interruption of supply

230.72(B) states the reason directly: remote installation minimizes the possibility of simultaneous interruption of supply to both normal and standby/emergency systems. Voltage drop and enclosure ratings aren't the stated rationale, and this is the opposite of the 230.72(A) grouping requirement, which applies only to the normal service disconnects.

Q2 NEC 230.72

A multiple-occupancy building has one disconnect serving several tenant units. Under what condition can that disconnect be restricted to authorized management personnel only, per 230.72(C)?

  1. A When each tenant signs a lease waiving direct access rights
  2. B When building management provides electric service and maintenance under continuous supervision
  3. C When the building has fewer than four occupancies
  4. D Whenever the disconnect is rated above 400 A
Show answer & explanation

Correct: B — When building management provides electric service and maintenance under continuous supervision

230.72(C) permits management-only access specifically when the building management provides electric service and electrical maintenance under continuous supervision. Ampere rating, lease waivers, and occupancy count aren't factors in this exception — without continuous management supervision, each occupant must have access to their own disconnect.

Q3 NEC 230.71

A switchboard is being used to provide six service disconnects, one per vertical section. What additional requirement applies?

  1. A Each vertical section must contain a motor control center unit
  2. B Barriers must be provided between vertical sections to maintain inadvertent contact protection per 230.62
  3. C No more than two of the sections may be adjacent to each other
  4. D Each section must have its own separate metering center
Show answer & explanation

Correct: B — Barriers must be provided between vertical sections to maintain inadvertent contact protection per 230.62

230.71(B)(3) requires barriers between vertical sections of a switchboard with one service disconnect each, specifically to maintain the inadvertent contact protection required by 230.62 when accessed from adjacent sections. Separate metering centers, adjacency limits, and motor control center units aren't part of this switchboard provision.

Q4 NEC 230.70

A homeowner asks if the main service disconnect can be mounted inside the guest bathroom for easy access. What does the NEC say?

  1. A It is allowed only in bathrooms larger than a specified size
  2. B It is allowed if the disconnect is behind a locked cover
  3. C It is allowed only if GFCI protection is provided
  4. D It is not permitted in bathrooms under any circumstance
Show answer & explanation

Correct: D — It is not permitted in bathrooms under any circumstance

230.70(A)(2) flatly prohibits installing the service disconnecting means in bathrooms — there's no exception for locked covers, room size, or GFCI protection.

All Services practice questions (Article 230)

Frequently asked questions

Where must the service disconnect be located?
Section 230.70(A) requires the service disconnecting means to be installed at a readily accessible location — either outside a building or structure, or inside nearest the point of entry of the service conductors. The intent is that anyone who needs to de-energize the building can reach it quickly without going deep into the structure.
How many disconnects are permitted at a service?
Under the long-standing rule in 230.71, not more than six switches or circuit breakers may serve as the service disconnecting means for any one service. Each disconnect must open all ungrounded conductors of the circuit it controls. More recent NEC editions have moved toward a single main disconnect requirement for one- and two-family dwellings — check the edition adopted in your jurisdiction.
What is the outdoor emergency disconnect added in recent editions?
Section 230.85, introduced in the 2020 NEC, requires a readily accessible means of disconnection installed outside one- and two-family dwellings. The intent is to let emergency responders quickly cut power from outside without entering the structure. Later editions refined the marking and interlock requirements for this disconnect.
Related articles
Services (Article 230) Full coverage of Article 230 — the service entrance rules that set the stage for the disconnect. Service & Feeder Calculator Size service conductors and confirm the disconnect rating against the calculated load. Feeders Feeders share the six-disconnect concept — know where the rule crosses over from Article 230 to Article 225. Overcurrent Protection (Article 240) The OCPD that protects service conductors must coordinate with the disconnect rating.
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