When we say that a customer’s meter “could not be read”, it basically means that the Disco was unable to read a customer’s meter due to inaccessibility occasioned by locked doors, customer not being at home etc. Where this is the case, the Disco cannot just proceed to estimate the bills of its customer. It must first notify the customer of its intention to estimate the customer’s bill in a manner approved by NERC and then proceed to estimate the bill of the customer for that period.
Regulation 3(1)(b) NERC’s Estimated Billing Methodology Regulation 2012.