The 'overhead electric cables' sign alerts drivers, particularly those driving tall vehicles, to high-voltage power lines crossing above the carriageway.
It is usually accompanied by a plate showing the safe height clearance limit to prevent accidental arcing or contact with power lines.
What this sign means
The sign displays a lightning flash symbol inside a red warning triangle, usually paired with a height restriction plate below.
It warns that high-voltage power lines span overhead and present an electrocution risk to oversized loads, cranes, and tall vehicles.
- Red warning triangle containing a electric bolt symbol
- Usually specifies maximum safe clearance height
- Found near railway power lines or grid crossovers
What to do when you see it
If you are driving a tall vehicle, ensure your total vehicle height is strictly below the indicated clearance limit before proceeding.
- Check overall vehicle height against the clearance plate
- Divert via an alternative route if your load is too high
- Never extend equipment like crane booms under cables
How this sign is tested
Questions cover the purpose of clearance indicators and hazards associated with high-voltage electrical overheads.
- Understanding height clearance warning signs
- Identifying hazards specific to tall vehicles and agricultural plant
- Interpreting supplementary height plates
Common mistakes
Assuming standard passenger cars are affected by height limits, or failing to know the exact physical height of a large load.
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Practise road sign questionsFrequently asked questions
Does this sign apply to standard cars?
Standard cars pass safely under overhead lines. The warning primarily targets high-sided vehicles, trucks, and farm equipment.
What does the height figure on the plate mean?
It indicates the maximum safe height of a vehicle that can pass under the power cables without risk.
Why can high voltage jump to a vehicle without touching it?
Electricity can arc through the air across short distances if a vehicle comes within the safety clearance gap.