The essential test tools and equipment needed to implement a safe isolation procedure in accordance with Electricity at Work regulations are a dedicated voltage indicator, a proving unit to verify the voltage indicator, a locking off device which can be secured in place using a padlock with unique key and a clear method of labelling the hazard. The Martindale LOK devices have been designed to fit a wide range of MCBs, RCBOs, fuse carriers and main switches and are compatible with Martindale PAD10 and PAD20 Series padlocks and TAG sets. The LOK series are available with different openings and include pushpin and grub screw designs in a range of different sizes to match most breaker configurations and applications even access is restricted.