This article discusses issues that can come up when billboard signs are located too near overhead lines passing horizontal to or above the signs. Signs installed too near electrical and communication lines can create safety hazards for the owners of the signs, the sign installers, the sign maintainers and the owners of the lines who are most often electrical and communication utilities.
Based on the operating voltages of overhead lines, CSA Standard C.22.3 No. 1, Overhead Systems, Clause 4.7.3 and Table 9 provides minimum horizontal and vertical clearances between utility lines and signs. The CSA standard is normally adopted into the standards of most utilities. To reduce the chance of electrical contacts, electrical and communication utilities take utmost care to conform to their own construction standards to ensure that their lines are not located too close to immovable objects such as signs.
Overhead pole lines are often used jointly by electrical and communication utilities and billboard signs are frequently installed after the utility lines are already in place. When a sign is found too near a utility line, in violation of the utility’s standard for line clearances, it leaves the utility in a predicament as to what to do next. Sometimes removing the sign is the only viable choice. Failure to deal with the situation is not an option as accidents and near misses are common by people working on signs.
The 2009 Canadian Electrical Code, Rule 34-106(1) provides requirements for location of signs in the vicinity of overhead electricity lines. The rule specifies that signs must be located so that:
- persons working on them are not likely to come into contact with overhead lines;
- no part of a sign or its support will interfere with normal work operations performed on electrical and communication lines as defined by the utility; and
- no part of a sign or its support is in such proximity to overhead lines as to create a hazard.
As you can appreciate, this rule identifies two distinct types of hazards concerning the proximity of signs to overhead lines — hazards to persons installing or maintaining the signs and hazards to utility personnel maintaining or making modifications to the overhead systems.
The danger to people who risk contact with overhead lines is most obvious. The generally accepted limit of approach for unqualified persons to electrical lines up to 44 kV is 3.05 metres (10 ft .07 in.) as specified in CSA Standard Z462-08, Workplace Electrical Safety, Table 1. Sign installers or maintainers could also be in violation of the provincial or territorial worker safety regulations, risking injury or death.
What may not be quite as obvious to the sign installers, electrical and communications utilities use large, specialized equipment and employ complex safety procedures in order to work safely many feet above the ground. If the location of a billboard sign interferes with properly setting up the equipment or it becomes impossible to carry out the line work according to the established safety procedures, the well-being of utility personnel could also be at risk.
As with previous articles, you should always consult with the electrical inspection authority in each province or territory as applicable for a more precise interpretation of any of the above.