NEC Article 230 — Services
Article 230 governs the installation of service conductors and service equipment — from the utility point of attachment to the service disconnect. Covers overhead and underground service entrance conductors, clearances, number of services permitted, and disconnecting means requirements.
One Service Per Building — 230.2
A building or other structure shall be supplied by only one service, with listed exceptions: size or occupancy requires multiple services, different characteristics (voltage, frequency), emergency or standby power, or fire pumps (each requires separate service under 230.2(A–E)).
Overhead Service-Drop Clearances — 230.24
Minimum vertical clearances for service-drop conductors from the point of attachment to the building or structure. Measured at final span after conductor sag.
| Location / Condition | Clearance | NEC Ref |
|---|---|---|
| Above roofs (accessible only by ladder) — conductors ≤ 300V to ground | 3 ft | 230.24(A)(1) |
| Above roofs with slope ≥ 4 in 12 (eave pass-over, ≤ 4 ft horizontal) | 18 in | 230.24(A) Exception 2 |
| Above roof — final span to weatherhead attachment where conductors turn down | 18 in | 230.24(A) Exception 3 |
| Above finished grade (open areas accessible to vehicles) | 18 ft | 230.24(B)(1) |
| Above residential driveways and commercial areas not subject to trucks | 12 ft | 230.24(B)(2) |
| Above residential property, sidewalks, and areas with pedestrian traffic | 10 ft | 230.24(B)(4) |
| Voltage exceeds 150V to ground — same residential locations | 12 ft | 230.24(B)(3) |
Clearances from Building Openings — 230.9
Service conductors installed as open conductors or multi-conductor cable without an overall outer jacket shall have at least the following clearances:
| Item | Clearance |
|---|---|
| Windows, doors, porches, fire escapes | 3 ft |
| Individual meter socket enclosures — insulated conductors | 3 ft |
| Above grade to point of attachment to building | 10 ft minimum |
Service Disconnecting Means — 230.70–230.82
| Requirement | Rule |
|---|---|
| Maximum number of service disconnects | Six disconnects per service (six-throw rule) — 230.71(A). All grouped in one location. |
| Location | Nearest point of entrance of service conductors to building or structure, or nearest readily accessible location — 230.70(A). |
| Marking | Each disconnect must be permanently marked to identify it as a service disconnect — 230.70(B). |
| Rating | Must be rated for the load: minimum 60A for single-family dwelling with >5 2-wire branch circuits OR load > 6 kW — 230.79(C). |
| Simultaneous disconnection | Must disconnect all ungrounded conductors simultaneously — 230.74. |
| Working space | Service equipment must comply with working space requirements of 110.26: minimum 3 ft depth, 30 in width, 6½ ft height. |
Underground Service-Lateral Conductors — 230.30
- • Shall be insulated or covered — bare copper is permitted where directly buried and used for a grounded conductor.
- • Direct-buried service conductors must comply with burial depth requirements of Table 300.5 (minimum 24 in for service-entrance cables, 24 in for rigid conduit, 24 in for direct burial).
- • Where subject to physical damage, must be protected in approved raceway.
- • Conductors entering a building or structure shall be protected by an approved enclosure or raceway from below grade to the service disconnecting means.
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