I have been handed a lead to have a look at, it was cut into three pieces, I was astounded to find that each of the pieces had no earth continuity. the active and neutral conductors tested ok. I could not get a reading on the earth even with an insulation test.
The lead did not have any obvious kinks or damage and looked reasonably new.
The pieces of the lead were each about three to four metres in length.

I cut one of the pieces in half and tested again this time one piece had continuity, I stripped the other piece, The earth conductor felt to be broken in one place (easily kinked). The conductor did not look to be damaged in any other way.

I don't know how leads are manufactured, But my thought is during manufacture, the tension may have been set to high on what ever type machine rolls the earth cable.

Does anyone have any theories on this?

Regards Graham

I once read a post about German NYM cable (non-metallic solid core cable used for in-wall wiring) that said there was a break in the conductor and the factory just wrapped it with a copper foil that was much thinner than the wire. Naturally it first worked, but under load the foil served as a fuse.

Gray,
I would say that this sounds a bit peculiar and a bit dangerous too!.
I would agree with you saying that it could have happened at the factory.
I've been on a tour through a cable factory and the flexes are made by spraying the plastic on to the pre-twisted insulated cores.
I'd say it is a tensioning problem, during manufacture.
I wonder how many more people have flexes like the pieces you have?.