AUSTIN ENERGY’S OVERHEAD ELECTRICAL LINE CLEARANCES

UNDERSTANDING COMMON POLE TYPES AND THE BUILDABLE AREA AROUND THEM

Written by Okkem Design

When designing structures in Austin, it is essential to understand and comply with Austin Energy’s overhead electrical line clearances. During permitting, Austin Energy (AE) requires that if an overhead electrical line exists on a property—excluding the service drop to the building—an elevation drawing must be provided to confirm that no part of any structure encroaches upon the required clearances. These regulations help maintain safety, prevent accidental contact, and ensure the continued reliability of the electrical grid. Understanding and maintaining proper clearance in real-world conditions prevents potential conflicts and redesign issues.

Utility poles on a property can support different types of electrical lines, and understanding these distinctions is essential for evaluating clearance requirements. Single-phase lines, which are common in residential areas, consist of a neutral line and a single energized (live) line. Two-phase and three-phase lines are more common near commercial and industrial areas, and consist of a neutral line and multiple energized lines, often arranged along a cross arm. On any pole type, there may be additional cables below the neutral line such as phone, fiber, cable, and internet lines, though these do not impact the electrical clearance requirements. The neutral line is always positioned below the primary (live) line(s), which are generally the highest wire(s) on the pole.

Utility poles themselves vary in height, typically ranging from 40’ to 55’, and their design can differ depending on the type of equipment they support. In addition to a regular single-phase pole, multi-phase lines can be run across poles with standard cross arms or narrow profile cross arms. Other poles may accommodate transformers and additional electrical components, which can alter required clearances.

To comply with clearance regulations, structures must maintain the following clearances: a 7’-6” horizontal sky-to-ground clearance from both sides of overhead primary, neutral, and secondary conductors; a 15’ radius around the neutral line; and a 15’ radius around all primary (live) lines. For multi-phase lines, the presence of multiple energized wires along the cross arm means that each line requires its own clearance radius. This means that a pole supporting a three-phase line will have three separate primary radius clearances to consider, each extending 15’ from its respective energized line. These overlapping clearance zones, in addition to the neutral radius and sky-to-ground clearance, can significantly impact the amount of buildable area around an overhead electrical system. 

The required clearances ensure that no part of a structure—including eaves, balconies, or overhangs—encroaches into the designated safe zone. However, it is crucial to acknowledge that these standard clearances can change depending on the presence of transformers and/or additional pole-mounted equipment. In such cases, the actual clearance requirements may be greater than the standard distances, requiring additional verification.

Since Austin Energy provides standard clearance diagrams illustrating common pole heights and configurations, it may be tempting to use them as definitive measurements for every project. However, field verification is necessary to avoid miscalculations due to site-specific factors rather than relying solely on standard drawings. Clearance distances should be measured and confirmed in real-world conditions because utility poles are rarely installed with absolute precision. Utility poles are not always perfectly upright, and even slight leaning or shifting over time can affect clearance measurements. Real-world conditions, including pole tilt, variations in wire sag, and non-standard spacing/mounting construction must be accounted for in any clearance evaluation.

By taking the time to evaluate the real-world clearances on a site during the design phase, project teams can prevent issues during permitting and construction and ensure compliance with Austin Energy’s requirements. Factoring in all clearance considerations early in the design process not only prevents conflicts but also minimizes risks associated with working near high-voltage electrical lines. Knowing the requirements and limitations of your site can save time and budget by avoiding re-designs during permitting and getting correct bids the first time.

For more detailed information, refer to Section 1.10 of the Austin Energy Design Criteria Manual or consult directly with Austin Energy to verify site-specific conditions.

Non-buildable area around single phase pole, leaning single phase pole, and three-phase pole