A bell hole box with an open bottom for protecting construction workers from wall cave-in when working below a surface of the Earth may utilize two, opposing, generally concave walls with generally straight panels portions. The two walls may be connected using multiple spreaders that are pinned or connected to each of the two, opposing walls. Each longitudinal end of the bell hole box is open to permit passage of a pipeline through it. Numerous vertical guard posts may be connected around a top frame rail and joined together with chains. The bell hole box may be lifted in and out of a hole with mounted lifting hooks.