A cable stringing block assembly is disclosed having a frame and axle assembly configured to hold a non-conducting sheave wheel. The sheave wheel is fabricated of a durable polymeric material. In one embodiment, the sheave wheel is self-lubricating, having a coefficient of friction less than 0.5. A handle is optionally affixed to the frame structure to facilitate transport of the block assembly. In another embodiment, a spring-biased fly gate facilitates side-loading of the cable. A helicopter arm can also be provided for helicopter loading of the cable. The cast aluminum frame can be anodized to disguise its appearance from scrap aluminum thieves and provide additional weather protection.