Cathodic Protection Training Course
Horizontal, vertical, borehole and disused-used oil-wells.
Groundbeds are designed to inject Direct Current electricity into the ground.
They are connected to the positive terminal of a transformer/rectifier or directly discharge the corrosion current from the base metal which is sacrificed to protect the subject metal.
In either case the ground at the centre of the groundbed is more positive that the surrounding ground. It has a higher electrical potential and will show this on a digital voltmeter.
It is good to be able to imagine a groundbed as a pile of electricity and this can be displayed by a computer using Excell.