Am I just being an ignorant numskull or shouldn’t these act just like a wire with clip at one end and a conducting wrist-attachment at the other (which is exactly what I thought they were)? I got one of the Belkin ones but when I checked it with a multimeter there was no electrical connection between the crocodile clip and the wrist end of the wire. I got another from Maplin (roughly speaking the UK equivalent of RadioShack) - almost identical but branded as Maplin’s own - and it was the same.