Applies to newly manufactured maximum demand indicators, class 1.0, intended to operate as attachments to watthour meters or varhour meters, coupled mechanically thereto and to indicate the maximum of average power, active or reactive, measured during successive equal intervals of time and to their type tests. Applies to the meters only as regards mutual effects between the maximum demand indicators and the meter. Maximum demand indicators of the same class may be attached to watthour meters or varhour meters of different accuracy class. Excludes maximum demand indicators based on thermal effects, those operated by impulses, and cumulative indicators, intended only for control purposes.