Service Disconnect Rules (NEC 230 Part VI)
Why this matters
A failed inspection on a service-disconnect placement issue costs the contractor a full re-trip, sometimes weeks of utility-coordination delay, and customer relationship damage that is hard to recover. The disconnect rules in NEC 230 Part VI changed materially in 2020 and again in 2023; a contractor whose mental model is the 2014 cycle is making decisions that no longer pass. Six disconnects grouped in one enclosure are out. Emergency-disconnect requirements for one- and two-family dwellings are now mandatory. Knowing the current rules - especially the differences between dwelling and non-dwelling and between the 2020 and 2023 cycles - is what separates the inspector-passing install from the one that comes back with a red tag.
Where the disconnect goes
NEC 230.70(A)(1) requires service disconnects to be:
Installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors.
The key phrases:
- Readily accessible: no ladders, no tools, no doors with locks the customer cannot operate
- Outside the building: legal anywhere on the exterior, no proximity rule
- Inside, nearest the point of entrance: typically interpreted as within 5 to 10 feet of where the service conductors enter the building (specific limit varies by AHJ; some jurisdictions interpret "nearest" strictly)
The contractor's safest play: install outside whenever possible. An outside-mounted disconnect satisfies the rule without the "nearest the point of entrance" debate.
The 2020 emergency-disconnect rule for one- and two-family dwellings
NEC 2020 added 230.85: every one- and two-family dwelling shall have an emergency disconnect located outside, accessible to first responders.
The 2023 NEC retained and clarified this. Three permitted configurations:
- Service disconnect outside (the disconnect itself satisfies the rule)
- Service disconnect inside, with emergency disconnect outside (the emergency disconnect ahead of the service disconnect)
- Meter disconnect outside, with service disconnect inside (the meter combination ahead of inside service disconnect)
Marking required: "EMERGENCY DISCONNECT" (or similar specific language per 230.85). The intent is that a first responder arriving at the scene of a fire can de-energize the home from outside before entering.
This rule is among the most-missed in residential work. A 2020 or later home with no outside disconnect fails inspection.
What the 2020 NEC actually did to the "six-throws" rule
Read this one carefully, because it is widely misstated in the field. NEC 230.71(A) still permits up to six service disconnecting means for a single service. The six-disconnect allowance was NOT eliminated.
What 230.71(B) changed in 2020 is WHERE they can live: two to six service disconnects must now each be in a SEPARATE enclosure, with permanent identification. The six-handle main-lug service panelboard, six breakers grouped in one can, is what went away.
So: one enclosure, one service disconnect. If the job genuinely needs more than one, they go in individual enclosures, marked. Existing six-in-one installs remain grandfathered.
Maximum number of disconnect throws
For a single service:
- New installation post-2020: up to six, but one per enclosure. Most residential work is a single main and should stay that way
- Multi-tenant building (apartment, mixed-use): each tenant unit can have its own service disconnect, but the building has one service-entrance combination per service entering the building
For services with multiple service-entrance taps, each tap requires its own disconnect ahead of branch distribution.
Accessibility requirements
NEC 110.26 working space rules apply to service disconnects:
| Voltage | Working space depth (Condition 1) | Working space depth (Condition 2) | Working space depth (Condition 3) |
|---|---|---|---|
| 0 to 150 V | 3 ft | 3 ft | 3 ft |
| 151 to 600 V | 3 ft | 3 ft 6 in | 4 ft |
Condition 1: exposed live parts on one side, no other live parts on the other side
Condition 2: exposed live parts on one side, grounded parts on the other side
Condition 3: exposed live parts on both sides
Additionally:
- 6 ft 6 inch headroom minimum
- 30 inch width minimum (or width of equipment, whichever is greater)
- Dedicated equipment space above the disconnect (6 ft high, equipment-width) free of foreign systems
A service disconnect in a closet jammed full of household storage violates 110.26. A disconnect behind a furnace where the working space overlaps the furnace clearance violates. Document the access at inspection.
Identification of disconnects
NEC 230.66 requires each service disconnect to be marked indicating its purpose. Engraved phenolic plate, embossed metal tag, or other permanent marking. Sharpie on the cover is not compliant.
For multiple disconnects (legacy installs with the six-throw rule pre-2020), each disconnect must be marked with its specific function.
For multi-tenant buildings, the disconnect marking should identify the unit it serves ("Disconnect for Apt 3B").
Disconnect overcurrent rating
Per NEC 230.90, each ungrounded conductor must have overcurrent protection rated no greater than its ampacity. For service-entrance conductors:
| Service rating | Typical SE conductor | Typical OCPD |
|---|---|---|
| 100A residential | 4 AWG copper SE-U cable | 100A main breaker or 100A fused disconnect |
| 200A residential | 2/0 AWG copper or 4/0 AWG aluminum SE-U | 200A main breaker |
| 400A residential | 600 kcmil aluminum SE-U | 400A main breaker (typically in panelboard or fused disconnect) |
| Commercial 600A+ | Per design | Per design, often fused switch |
The OCPD must also satisfy the available fault current (AIC rating) per the utility-supplied figure.
Ground-fault protection (commercial)
NEC 230.95 requires ground-fault protection on services 1000A or greater at 150 to 1000V. The ground-fault sensor and relay are installed at the service-entrance equipment. Residential below 1000A is not covered by this rule.
For services that include it, NEC 230.95(C) requires a performance test when the system is first installed on site, with the written record given to the AHJ. Periodic retesting after that is a maintenance practice (NFPA 70B territory), not an NEC mandate, so do not tell a customer the code requires an annual test.
Disconnect for one- and two-family dwellings: practical examples
Standard install: outside service disconnect
This is the default build on a new or replacement 200 A residential service, and the one that starts the fewest arguments with an inspector.
On the exterior wall: a meter-main combination, meter socket and 200 A main breaker in one listed enclosure, set so the meter reads at roughly eye height and the handle is operable from grade. That single main breaker is the service disconnect, and with the correct field marking it also satisfies 230.85, so no second outside device is needed.
From the meter-main, a four-wire feeder (two ungrounded, one grounded, one equipment grounding conductor) runs to the indoor panelboard. That indoor panel is now a subpanel, not service equipment: neutral bar isolated from the can, equipment grounds on their own bar, no main bonding jumper.
The grounding electrode conductor lands at the outside disconnect enclosure, not at the indoor panel. Ground rods and the water-pipe bond terminate there as well.
Working space per 110.26 is 3 feet deep in front of the disconnect, 30 inches wide, and headroom clear. Walk the wall before you set the enclosure: condenser, hose bib, downspout, gas meter, and the spot where the trash cans live all eat that space, and the inspector measures it as-found, not as-drawn.
Marking: the equipment carries the manufacturer's mark identifying it as suitable for use as service equipment per 230.66, and the field label required by 230.85 goes on the outside disconnect. The indoor panel gets a full circuit directory plus a label naming what feeds it.
What this build buys you: no debate about "nearest the point of entrance," no unprotected service conductors running through finished space, a de-energization point first responders can find, and a clean path later if the customer adds a generator interlock or PV at the indoor panel.
References
- NFPA 70 (NEC) 2023, Article 230, Part VI (Service Equipment Disconnecting Means).
- NFPA 70 (NEC) 2023, Section 230.66 (Marking).
- NFPA 70 (NEC) 2023, Section 230.70 (Disconnecting Means location and accessibility).
- NFPA 70 (NEC) 2023, Section 230.85 (Emergency Disconnects).
- NFPA 70 (NEC) 2023, Section 230.95 (Ground-Fault Protection of Equipment for Services).
- NFPA 70 (NEC) 2023, Article 110.26 (Spaces about Electrical Equipment).
- NFPA 70 (NEC) 2023, Article 225 (Outside Branch Circuits and Feeders).
- UL 67 (Panelboards) and UL 50 (Enclosures).
- Local jurisdiction amendments to NEC (varies; check with AHJ).
- Manuall internal: Electrical Service Entrance Meter Base, Electrical Service Panel Upgrade, Electrical Commercial Three-Phase Service Entrance.