What should be used to fill a hole where cable goes through a masonry wall?

The use of a mastic-type sealer to fill a hole where cable passes through a masonry wall is appropriate because it provides a flexible and durable seal that can accommodate movement and expansion in the materials. Mastic sealers are designed to create a strong bond with both the cable and the masonry, preventing moisture ingress and maintaining the integrity of the wall. This is particularly important in electrical installations, as it helps to protect against water penetration and potential damage to the electrical components.

Cement mixtures, while solid, can crack over time due to shifts in the wall or cable movement, which may lead to gaps that allow moisture intrusion. Silicone caulk can be effective in certain applications but may not adhere as well to masonry surfaces compared to mastic sealers. Foam insulation is typically used for thermal insulation and may not provide the necessary moisture barrier or strong bonding required for sealing around electrical installations. Therefore, the mastic-type sealer is the better choice for this specific application.