Martindale lok6 universal fuse carrier isolation lock martindale lok6 p the martindale lok6 is a universal locking off device for fuse carriers designed to restrict finger access to live contacts and prevent the reinsertion of a fuse whilst maintenance is in progress the lok6 is ideally suited to red spot and other similar style fuse holders it is easily adjustable to fit fuse holders from 20a to 100a providing a one size fits all solution p p to reduce the risk of use in live worki