(a)  Accessibility. - In the interest of safety and convenience to the customer, and as a measure of economical operation to the utility, it is required that all meters should be located at the curb; provided however, that when such location is impractical, meters shall be placed outside of the customer's building as near as possible to the point where the utility's "service connection" joins the "customer's service line''; provided, further, if neither of the foregoing requirements can be complied with on account of physical, economic, or climatic conditions, the meter may be placed within the building, preferably in the cellar, and when so placed within the building, the meter shall be so located that it will be easily accessible for reading and protected from freezing and mechanical damage.

(b)  Meter Grouping. - When a number of meters are grouped, every meter shall be tagged as to indicate the particular customer or premise served by it.