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Understanding CAN/CSA C22.3 No. 6-13:2017: Electrical Clearance Requirements for Power Lines in Built‑Up Areas
A guide to the Canadian standard for safe clearances of overhead and underground electric transmission and distribution lines in urban and suburban environments.
Scope and Purpose
CAN/CSA C22.3 No. 6-13:2017, titled Electric Power Lines in Built‑Up Areas – Minimum Electrical Clearances, is a key component of the CSA C22.3 series on electric power transmission and distribution systems. This standard specifies the minimum electrical clearances required for overhead and underground power lines that operate at voltages above 750 V and are located within built‑up areas — i.e., urban, suburban, and other densely populated zones where public access is unrestricted.
The purpose of the standard is to protect life and property by ensuring that live parts are separated from buildings, bridges, signs, trees, and other objects by distances sufficient to prevent flashovers, inductive coupling, and accidental contact. It addresses both vertical and horizontal clearances, taking into account line sag, swing due to wind, ice loading, and temperature effects.
While the standard is primarily intended for use by electric utilities, it is also referenced by municipal planners, design engineers, and regulatory authorities across Canada. It harmonizes with the Canadian Electrical Code, Part III (C22.3 series) and supplements the general safety requirements of CSA C22.1 (Canadian Electrical Code, Part I).
Success: By adopting the clearance rules of CAN/CSA C22.3 No. 6-13:2017, utilities can reduce the risk of electrical accidents and improve the reliability of power delivery in densely built environments.
Technical Requirements
The standard defines clearance values that depend on the nominal phase‑to‑phase voltage, the type of conductor, the location category (e.g., roadway, sidewalk, building), and whether the line is overhead or underground. Clearances are expressed as minimum distances in metres under specified loading conditions.
Overhead Line Clearances
For overhead conductors, the standard provides vertical clearances above ground, roofs, balconies, and signs, as well as horizontal clearances from walls, windows, and other structures. The values are adjusted for:
- Voltage class: from 750 V up to 300 kV and higher.
- Conductor temperature: clearances are based on the conductor at 50 °C (or the maximum operating temperature, whichever is higher).
- Wind and ice loading: extreme wind (1‑in‑50‑year event) and heavy ice loads are considered when calculating sag and blow‑out.
Warning: The clearance values in this standard are minimum distances. Local jurisdictions may require greater clearances, particularly in areas subject to seismic activity or heavy snow accumulation.
Underground Line Clearances
For underground cables, the standard mandates separation distances from other buried utilities (gas, water, telecom), building foundations, and structures. Key requirements include:
- Minimum cover depth for direct‑buried cables (typically 0.75 m for roads and 0.6 m for private property).
- Horizontal clearances from building footings (usually 0.6 m).
- Separation from other utilities to minimize corrosion interference and facilitate maintenance.
| Nominal Voltage (kV) | Location | Minimum Vertical Clearance (m) | Minimum Horizontal Clearance (m) |
|---|---|---|---|
| 0.75 – 75 | Roadways & streets | 6.0 | 1.5 |
| 0.75 – 75 | Walkways & private property | 5.0 | 1.0 |
| 75 – 150 | Roadways & streets | 7.0 | 2.0 |
| 75 – 150 | Over buildings (roofs) | 5.5 | 2.5 |
| 150 – 300 | Roadways & streets | 8.5 | 3.0 |
| 150 – 300 | Over buildings (roofs) | 7.0 | 3.5 |
The values above are for bare conductors operated at 50 °C. For covered conductors or higher temperatures, additional clearance increments apply (refer to the standard’s annexes for detailed adjustment factors).
Implementation Highlights
When applying CAN/CSA C22.3 No. 6-13:2017, engineers and planners should focus on the following practical aspects:
- Route selection: Use the clearance tables early in the design phase to avoid conflicts with new development or existing structures.
- Field measurements: After construction, verify clearances using calibrated instruments (e.g., laser distance meters) and document them for compliance records.
- Vegetation management: The standard also indirectly governs tree trimming near overhead lines. Although specific horticultural methods are outside the scope, the clearance distances dictate where pruning is required.
- Maintenance upgrades: For existing lines that do not meet the 2017 edition’s requirements, a pre‑existing installation may be allowed to continue operating if a safety assessment, per Clause 9 of the standard, demonstrates equivalent safety.
Tip: When upgrading an older line to the 2017 clearance rules, consider using spacers for bundled conductors or replacing bare wire with covered conductors. This can reduce the required horizontal clearances and avoid relocation of utility poles.
Compliance Notes
CAN/CSA C22.3 No. 6-13:2017 is referenced in provincial and territorial electrical safety regulations across Canada. Utilities must demonstrate compliance through design calculations, field verification, and periodic audits. Key compliance points include:
- Documentation: Maintain a clearance calculation sheet for each line segment, showing input assumptions (conductor type, temperature, ice, wind) and the resulting clearances compared to the standard’s minima.
- Third‑party review: For new lines in built‑up areas, many jurisdictions require a professional engineer’s seal on the clearance plan.
- Re‑assessment: Any modification that could affect clearances (e.g., raising voltage, changing conductor size) triggers a re‑assessment against the current edition of the standard. The 2017 edition is reaffirmed until a new edition is published (typically every five years).
- Harmonization: The standard is aligned with IEEE Std 516 (live‑line work clearances) and CSA C22.3 No. 1 (overhead systems), but always take the most restrictive requirement applicable.
Danger: Non‑compliance with the minimum clearances can lead to electrocution, fires, and service interruptions. In addition, regulators may impose penalties or require immediate corrective action, such as temporary line de‑energization until clearances are restored.
Frequently Asked Questions
Q: Does CAN/CSA C22.3 No. 6-13:2017 apply to communication cables mounted on the same poles as power lines?
A: It specifically covers clearances for power lines. However, Clause 5.3 recommends that communication cables maintain a minimum 1 m vertical separation from power conductors when jointly used, and follow the coordination rules of CSA C22.3 No. 5.
A: It specifically covers clearances for power lines. However, Clause 5.3 recommends that communication cables maintain a minimum 1 m vertical separation from power conductors when jointly used, and follow the coordination rules of CSA C22.3 No. 5.
Q: Are these clearances mandatory for temporary construction lines or emergency repairs?
A: Yes, the standard applies to all electric power lines in built‑up areas, including temporary installations. Emergency repairs are expected to restore clearances as soon as reasonably practicable, with a documented risk assessment retained on file.
A: Yes, the standard applies to all electric power lines in built‑up areas, including temporary installations. Emergency repairs are expected to restore clearances as soon as reasonably practicable, with a documented risk assessment retained on file.
Q: How does the standard treat lines that pass near buildings before they are constructed?
A: The standard requires that clearances be evaluated based on the final configuration of the surrounding environment. If a building is planned, the utility must ensure that the line either meets the required clearance to the future building or that the building is set back enough to maintain the distance. Developers are often required to coordinate with utilities during permitting.
A: The standard requires that clearances be evaluated based on the final configuration of the surrounding environment. If a building is planned, the utility must ensure that the line either meets the required clearance to the future building or that the building is set back enough to maintain the distance. Developers are often required to coordinate with utilities during permitting.
Q: Where can I obtain the official text of CAN/CSA C22.3 No. 6-13:2017?
A: The standard is available from CSA Group’s store (store.csagroup.org). It is protected by copyright and must be purchased; however, many utilities and libraries have copies for reference. Always use the latest published edition.
A: The standard is available from CSA Group’s store (store.csagroup.org). It is protected by copyright and must be purchased; however, many utilities and libraries have copies for reference. Always use the latest published edition.
Last updated: 2026