By Les Stoch
Safety issues can arise when billboards and other signs are installed where nearby overhead electrical and communications lines pass horizontal to or above them. Signs installed too close to these lines can create hazards, not only for the installers themselves, but also for the signs’ owners, service professionals and maintenance staff, as well as the owners of the lines, which are most frequently electrical and communication utility providers.
Based on the operating voltage of these overhead lines, Canadian Standards Association (CSA) C.22.3 No. 1, Overhead Systems, Clause 4.7.3, Table 9 provides minimum horizontal and vertical clearances between utility lines and signs (see Figure 1) to avoid physical contact with electrical conductors. It is important to note conductor swing—due to prevalent weather conditions—must be added to all of the horizontal clearances. The degree of conductor swing is based on pole spans, line sags and whether the lines are considered sheltered or unsheltered.
To reduce the chance of electrical contact, utility providers take the utmost care to conform to their own construction standards. CSA’s clearances are normally adopted into these standards for most utilities, to help ensure their lines are not located too close to immovable objects, including but not limited to signs.
Pole-mounted overhead lines are often jointly used by electrical and communication utilities. Signs, especially billboards, are frequently installed after these lines are already in place, but when a sign is found too near a utility line—in violation of that utility’s standard for line clearances, as well as the CSA standard—it leaves the utility provider in a predicament as to what to do next.
Sometimes, the only viable choice is to remove the sign. Either the utility provider or the local electrical safety authority may request to have this done. Failure to deal with the situation is not an option.