It is important to differentiate between what is maintenance and what is an improvement. Repairs to the electric fence will be maintenance but installing a new fence or upgrading an existing fence will be an improvement.
Improvements are then differentiated to either be a necessity (non-luxurious improvement) or not a necessity (luxurious improvement). The arguments for necessity will be based on a number of factors including the financial status of the scheme and the location of the scheme.
PMR 29 deals with the approval needed for both these types of improvements.