Engineering Technical Bulletin
Overhead Electrical Infrastructure Clearances
Communication between all parties involved in the design, construction, renovation, for the use and maintenance of buildings near overhead electrical infrastructure is key. Planners, architects, developers / contractors, and property owners must be informed and work together to ensure all laws, regulations and local requirements are met for the safety of workers and occupants.
New Buildings or Additions to Buildings
It is essential that Burlington Hydro is notified on proposed projects early in the design phase to review and provide feedback. Site plan applications should be provided, including the drawings, to capture any conflicts before any permit is issued by the municipality. Ideally, Burlington Hydro will be asked to provide pre-design input.
For any new building or additions to existing buildings, there are several codes and regulations that govern the proximity to overhead electrical infrastructure that must be adhered to by all stakeholders. The Ontario Building Code (OBC), Ontario Electrical Safety Code (OESC), and Ontario Regulation 22/04 – Electrical Distribution Safety all have the same requirements regarding clearances. These clearances take into account the swing of power lines / conductors as per the OBC and apply to the outermost part of the building, which includes balconies, fire escapes, flat roofs, or other projections beyond the face of the building as shown in Figure 1.
The OBC regulates the design and construction of all new buildings as well as additions, alterations and the change of use of existing buildings. Applying Article 3.1.19.1, Above Ground Electrical Conductors; Clearances to Buildings, minimum horizontal clearances to overhead electrical infrastructure are as follows:
Overhead Clearances
| Clearance from overhead power lines | <750 volts | >750 volts |
|---|---|---|
| Radial to conductor | 3 metres (10 feet) | 5 metres (16.5 feet) |
| 0-750 volts | 1.5 metres (5 feet) | 1.0 metres (~3 feet) |
| Along the overhead pole line (from a vertical line drawn from power line to ground level) | 2 metres (6.5 feet) | 5 metres (16.5 feet) |
All stakeholders should contact Burlington Hydro to determine the requirements for any specific design scenario. According to CSA C22.3 No. 1, permanent or temporary structures / buildings or their extensions, should not be over or underneath overhead electrical infrastructure.
Examples of instances when these clearances become necessary for workers and occupants:
- Workers: Using scaffolding during construction, putting up signs and lighting, or other equipment to maintain the building, i.e. resurfacing, window washing or use of cranes.
- Occupants: Hanging clotheslines, business signs, flags, or general reach from a balcony
Burlington Hydro should be contacted prior to any activity that will come within 3 metres of the overhead electrical infrastructure, such as tree trimming or working on the sides of a building. According to Ontario’s Occupational Health and Safety Act and the Electrical Safety Code, only Burlington Hydro's employees or approved contractors can work in proximity to these lines.
Figure 1: Ontario Building Code Clearance Requirements
Maximum swing: Ontario Building Code Clearance Requirements stipulate that the greatest horizontal displacement of any point on a power line, from its position at rest. In other words, the maximum swing is the distance a wire strung on a pole can potentially swing in any direction.
Figure 1: Ontario Building Code Clearance Requirements - Clearance from Medium Voltage (>750 volts)
Maximum swing for medium voltage overhead electrical lines and equipment. Refer to the Overhead Clearances Table.
Figure 2: Ontario Building Code Clearance Requirement - Clearance Low Voltage (<750 volts)
