1A utility shall not make any changes in heating value, pressure, specific gravity, gas composition, or other condition or characteristic of the gas it delivers which would impair the safe, efficient utilization of the gas in customers’ appliances without tariff revisions setting forth the changes, the prior approval of the Commission, and adequate notice to the customers. Any such change by the utility shall be accompanied by a general inspection and adjustment of all appliances that would be affected thereby to the extent necessary that such appliances may operate as efficiently and give as good service as was possible before the change. This shall be done promptly, without direct charge, and with a minimum of inconvenience to the customer.
