By Mike Holt
NEC^® Consultant

Note: This article is based on the 2026 NEC^®.

Do you know the rules for branch circuits and feeders installed outdoors?

Introduction
Outdoor conductors can serve many purposes, such as providing lighting, power for outdoor equipment, or power to separate buildings. Outside installations are subject to physical damage and they are exposed to the environment.

Article 225 contains the requirements for outside branch circuits and feeders installed on or between buildings, structures, or poles. Figure 01

The requirements in Article 225 are in addition to the requirements contained in Article 210 for Branch Circuits and Article 215 for Feeders.

Note: The requirements for outdoor service conductors are contained in Article 230.

Outdoor Conductor Size and Support
The sizing of overhead conductors is based on the need for adequate mechanical strength to support the weight of the conductors. These conductors must withstand wind, ice, and other adverse conditions.
Conductor Spans. The minimum sizing are as follows:

• Up to 50 ft of conductor span, 10 AWG
• Over 50 ft of conductor span, 8 AWG, unless supported by a messenger wire [225.6(A)]
  

Point of Attachment. The point of attachment to a building for overhead conductors must be at least 10 ft above the finished grade [225.16(A)]. Open conductors must be attached to buildings by fittings identified for use with conductors, or noncombustible/nonabsorbent insulators securely attached to the building [225.16(B)].

You can't use trees or other vegetation to support overhead conductors [225.26]. Masts for supporting overhead conductors must have adequate strength, braces, or guy wires to safely withstand the strain caused by the overhead conductors [225.17(A)].

Overhead conductors are not permitted to be attached to the mast above a coupling located above the roof or last point of securement [225.17(B)].

Overhead Conductor Clearances
Vertical Clearance
Overhead conductor spans must maintain a vertical clearance as follows:

• 10 ft above finished grade, sidewalks, platforms, or projections that permit personal contact for conductors supplied by 208Y/120V or 120/240V circuits [225.18(1)].
• 12 ft above residential property and commercial areas not subject to truck traffic for conductors supplied by 120/240V, 208Y/120V, or 480Y/277V circuits [225.18(2)].
• 15 ft above the "item 2" areas, where the voltage exceeds 300V to ground [225.18(3)].
• 18 ft above public streets, alleys, parking areas subject to truck traffic, non-residential driveways, and other areas traversed by vehicles [225.18(4)].
• 24.5 ft above railroads [225.18(5)].
  

Note: Overhead conductors above pools, hot tubs, diving structures, observation stands, towers, or platforms must comply with the requirements contained in 680.9.

Above Roofs. Conductors over a room must maintain a vertical clearance of 8 1/2 ft above the roof surface for not less than 3 ft from the roof edge [225.19(A)].

The conductor clearances from the roof can be reduced to 3 ft if the slope of the roof meets or exceeds 4 in. vertical rise for every 12 in. of horizontal run [225.19(A) Ex 2].

Other Structures. Overhead conductors must maintain a clearance of at least 3 ft from signs, chimneys, radio/television antennas, tanks, and other nonbuilding structures [225.19(B)].

Horizontal Clearances
Overhead conductors must be at least 3 ft horizontally from buildings [225.19(C)].

Overhead conductors must maintain a clearance of at least 3 ft from windows that open, doors, porches, balconies, ladders, stairs, fire escapes, or similar locations [225.19(D)(1)]. The final span of overhead conductors above a window are not required to maintain the 3-ft distance from the window [225.19(D) Ex].

Overhead conductors within 3 ft measured horizontally from the platform, projection, or surface from which they might permit personal contact must have a vertical clearance of 10 ft [225.19(D)(2)].

Overhead conductors cannot be installed under an opening through which materials might pass or obstruct an entrance to these openings [225.19(D)(3)].

Outside Raceways
Raceways on exterior surfaces of buildings or structures must be arranged to drain [225.22]. Figure 02

Note: Get with your AHJ on this rule!

Where an outside raceway enters a building, it must be sealed with a sealant that is identified for use with the conductor insulation [225.27].

Note: The sealing compound is intended to seal the raceway to prevent condensation from entering the equipment through the raceway.

Number of Feeders to a Building
A building can only be supplied by one feeder, except as follows:

Special Conditions. More than one feeder is permitted to supply the following [225.30(A)]:

• Fire pumps
• Emergency systems, Legally required standby systems, or Optional standby systems
• Parallel power production sources
• Systems designed for connection to multiple sources of supply for the purpose of enhanced reliability
• Electric vehicle power transfer systems
• Docking facilities
  

Common Supply Equipment. Up to six feeders originating in the same panelboard or distribution equipment are permitted to a building if the disconnects are grouped at the separate building [225.30(B)].

Special Occupancies. With special permission, more than one feeder can supply multiple-occupancy buildings where there is no space for supply equipment that is accessible to all occupants; and for buildings so large that two or more supplies are necessary [225.30(C)].

Capacity Requirements. Where the capacity requirements exceed 2000A, more than one feeder is permitted [225.30(D)].

Different Characteristics. For different voltages, frequencies, or uses (such as controlling outside lighting from multiple locations) more than one feeder is permitted [225.30(E)].

Documented Switching Procedures. Where documented safe switching procedures are established and maintained more than one feeder is permitted [225.30(F)].

Disconnecting Means
A disconnecting means is required for all feeders that supply a building or structure [225.31(A)].
Figure 03

Inside. The feeder disconnect can be located inside the building nearest the point of entrance of the feeder conductors [225.31(B)].

Outside. If the feeder disconnect is located outside of the building, the disconnecting means can be on or within sight of and not more than 50 ft from the building [225.31(B)].

Feeder conductors under at least 2 in. of concrete or encased in at least 2 in. of concrete are considered outside a building [225.31(B)].

Grouped. The feeder disconnecting means can consist of no more than six switches/circuit breakers in a single enclosure or in separate enclosures grouped together [225.33(A)].

If there's more than one disconnect, they must be grouped in one location and marked to indicate the loads they serve [225.34(A)].

Remote. The disconnects for fire pumps, emergency systems, legally required standby systems, or optional standby systems must be installed remotely from the normal power disconnect [225.34].

Plaque. If a building is supplied by more than one feeder or a feeder(s) and service(s), a permanent plaque or directory must be installed at each feeder and service disconnect location. The plaque(s) must identify all other feeders/services supplying the building, plus the area served by each disconnect [225.37].

Disconnect Rating
The feeder disconnecting means must have an ampere rating of at least:

• 15A, for a single branch circuit [225.39(A)].
• 30A, for two 2-wire branch circuits [225.39(B)].
• 100A, for a one-family dwelling [225.39(C)].
• 60A, for all other installations [225.39(D)].
  

Dwelling Unit Emergency Disconnect
Location. An emergency disconnect is required for one- and two-family dwellings supplied by an outside feeder. The emergency disconnect must be readily accessible and located outdoors either on the dwelling unit or within sight of and within 50 ft from the dwelling unit [225.41(A)(1)].

The service disconnect for a one- and two-family dwellings required by 230.70(A)(1) satisfies this outdoor emergency feeder disconnect requirement [225.41(A)(1) Ex].

Multiple Disconnects. If a one- and two-family dwellings has more than one emergency disconnect, those disconnects must be grouped [225.41(A)(3)].

Disconnect Marking. The emergency disconnect enclosure must be marked "EMERGENCY DISCONNECT." The marking must be of sufficient durability to withstand the environment, cannot be handwritten, and must be permanently affixed to the equipment [225.41(C)].

The marking or label must be on the outside front of the disconnect enclosure with a red background and white text. And the lettering must be at least 1/2 in. high [225.41(C)].

Getting Outside Circuits Right
Outside branch circuits and feeders require more than choosing the right conductor size.

• Before the job begins, verify the overhead clearances, conductor support, raceway sealing, and the location and rating of the building disconnect.
• If supplying a separate building with a feeder, determine how many supplies are permitted and where the building disconnect is required to be located.
• Plan these details before installation to prevent failed inspections, costly rework, and unsafe conditions.