A cross arm is provided, for use in a support structure for conductors within an electrical grid. The cross arm is made of weather resistant glass fiber reinforced two component polyurethane based polymers and has a “C” cross sectional shape typically arranged in a double configuration. Pairs of the cross arms are attached to utility poles in a parallel position on opposite sides of the utility pole to meet predefined design conditions. Alternatively, a single cross arm may be attached to a utility pole.