Probably not the best idea (what if someone operates the crane) but in the absence of anything else its better thatn nothing.

Hi Allan, Yes it is Riggers chain blocks I was referring to. My concern would be that if someone did fall would the block be man enough to take the shock load or could the guts get ripped oiut it with the force? Obviously this depends on the rating of the block but I'm not sure that much thought is given to that when someone takes the decision to clip on. I guess I'm just thinking how much more effort would it be to get scaffs in to put a couple points to clip to in a given work area.

It was riggers I was referring to. I was just making the point that it wouldn't take much to get the scaffs to rig them up a couple points overhead to clip to. I know the blocks are rated to 2 tonne but that is when a weight is gradually taken up through use of the chains, I am concerned more about the shock load placed on the block if a person was to fall, as this can be many times the weight of the individual. Not sure on the calcs but it can very surprising the amount of force someone dropping 10ft can generate

Just asked a lifting expert at Vertikal Days and he said under no circumstances should you hook your lanyard on to the hook of a set a chain blocks. Chain blocks are for lifting, lowering and suspending a load but not for accepting a shock load. He also mentioned the catch on the hook of the chain block wasn't suitable and sufficient to prevent the lanyard being ripped off the block during a potential fall.