Under what condition should communications wires not be attached to a cross-arm?

Communications wires should not be attached to a cross-arm if it carries electric power conductors because this presents a significant safety hazard. When communications wires are run alongside or attached to power conductors, there is a risk of electrical interference and accidental contact that can lead to dangerous situations such as electrocution or power outages.

Having the communications wires physically close to or crossing paths with high-voltage electric power conductors can also create issues of signal degradation and interference, which can impact the performance of low-voltage communication systems. Additionally, the differences in voltage can pose a risk of electrical arcing if there is a fault in the power system, underscoring the importance of keeping these systems properly separated for both safety and functional integrity.

Other conditions, referenced in the other options, do not inherently prevent the attachment of communications wires to a cross-arm as effectively as the presence of carrying electric power conductors does. For instance, whether a cross-arm is not grounded or is made of metal does not directly affect the potential hazards in the same manner as the high voltage from electric power conductors. The low voltage configuration suggests some safety in placement but does not eliminate concerns regarding proximity to high voltage lines. Thus, the safest practice is to keep communications wires away from