The BMC has issued a warning over some of the bolts in the Slate quarries in Llanberis after a bolt failed and subsequently Mark Reeves tested a number of bolts and found that some failed at very low loads.
As with all bolts, it is worth treating them with caution. If you notice any are loose, then report them! If you would like to support the bolting in Llanberis, you can donate to the North Wales Bolt Fund, or go here for more information.