All electricity apparatus situated on private land should be covered by at least one form of consent.
If the line only feeds your property then this is deemed a service and no agreement is required. If the equipment supplies anyone else this is called "a main" and a consent is required.
Sometimes the words "a main" might be recorded on your deeds. The majority of wood pole lines and lower voltage underground cables are covered by a Wayleave Agreement.
When property is sold the electricity company should renegotiate this wayleave, but invariably they are not advised of the new owners and the wayleave payment is either still paid to the previous owner or the payments just stop. Sometimes the payment will be just transferred to the new owner but this cannot always be guaranteed as accurate.
Many farmers buy and sell land over the years and never check to see if the equipment they have on their land is covered by any agreement.
BLB Utilities take on wayleave assessments to ensure that the correct payments are being paid to the correct land owners at the appropriate rate.