Video: Recognizing dangerous lines
Learn to distinguish medium-voltage, low-voltage and telecommunication lines on utility poles. This video explains what to look for and the risks associated with each type.
Different types of lines on utility poles
Danger
Always stay at least three metres away from power lines, whether they are covered or not.
And if power lines have fallen to the ground, always stay back at least 10 metres. Never try to move them and call 911 immediately.
Medium-voltage lines (750–34,500 volts)
Location: At the top of poles, mounted on insulators that look like small porcelain bowls.
Appearance:
- Thin metal wires
- Although usually bare, they sometimes have a grey protective cover
Configurations include:
- Usually one or three wires
- Up to six wires
Hazard: Risk of electrocution, even without contact.
Deadly danger: Keep away
Always keep people, tools and materials at least three metres away from medium‑voltage lines. At that distance or closer, an electric arc can occur between the power lines and your body, causing electric shock or even fatal electrocution. Much like the static shock you get when you rub your feet on a carpet, electricity can create an arc and travel through the air or an object you are holding and shock you. These arcs can be fatal.
Why don’t medium-voltage lines have an insulating sheath?
For practical and economic reasons, medium‑voltage lines aren’t covered with an insulating sheath: the surrounding air acts as an insulator. That’s why the lines are installed at height. Never go near them or bring anything close to them.
In some cases, the medium‑voltage lines are covered to protect them from vegetation. It can be useful to install covered lines in certain areas, especially wooded sectors, to improve power system reliability in severe weather. But be careful! Whether they’re bare or covered, medium‑voltage lines are always extremely dangerous. Never go near them or bring anything within three metres of them.
Low-voltage lines (120–600 volts)
Low-voltage lines are used to connect homes and other buildings to the grid.
Location: Directly under medium‑voltage lines.
Appearance:
- Two insulated black wires twisted around a bare metal wire
- Three insulated black wires stacked one above the other
- Three bare wires, stacked one above the other (less common)
Hazard: Risk of serious electric shock. Avoid all contact.
Never within 3 metres of a power line
Low-voltage lines can carry several hundred amps. Even if they’re covered, the danger is very real, since the cover may be cracked or damaged.
Telecommunication lines (around 12 volts)
These lines provide telephone and cable service.
Location: Under low-voltage lines
Appearance: Large cables covered with a black insulating sheath
Property: These lines don’t belong to Hydro‑Québec.
Hazard: Risk of injury is low but not zero. Avoid all contact.
Avoid all contact
Even though telecommunication lines don’t normally pose an electrical hazard, you should still avoid touching or leaning on them. If there’s a short circuit, fault or electrical storm, these lines could become dangerous and cause an electric shock and injuries.
Transmission lines
Wondering about the bigger wooden support structures or metal towers? They’re probably holding up high-voltage power lines that carry electricity over long distances.
These structures are subject to even stricter safety rules. Be very careful: their power and reach demand extreme vigilance.
Read the safety rules for transmission lines.