Electric rates for Massachusetts customers at National Grid will spike to 16¢ per kilowatt-hour (kWh), or higher, if customers continue to purchase their electricity supply from National Grid instead of shopping for a competitive electric supplier.

Massachusetts customers now have the power to choose their electricity supplier, in the same manner they can choose their long distance, cellular, and broadband provider. However, if customers don't shop for an electric supplier, their local utility continues to supply the customer under a program known as "basic service."

National Grid's electric rates for basic service electricity supply are set to spike this winter, reflecting uncertainty in the market, fears of electricity shortages, and constrained natural gas pipeline capacity.

For residential customers, National Grid's basic service rate as filed with the Massachusetts Department of Public Utilities is 16.182¢/kWh, for the period November 2014 through April 2015. That's double the current basic service rate of about 8¢/kWh.

Commercial customers (G-1) at National Grid may either be on a fixed basic service rate, or a monthly variable basic service rate, and rates are increasing under both scenarios.

For fixed price commercial customers, National Grid's basic service rate will be 15.138¢/kWh for the period November 2014 through April 2015, which is again nearly double the current rate of 7.7¢/kWh.

For commercial customers on National Grid's variable rate plan, the basic service rate will exceed 20¢/kWh in the months of January and February, and will vary from 9¢ to 15¢ in the remaining months of the November 2014 to April 2015 period.

For industrial customers (G-2, G-3), basic service rates have only been filed for the period through January 2015.  The industrial prices vary by the part of the state in which the customer is located, but generally, the industrial National Grid basic service electric rate will be 9¢/kWh for November 2014, 18¢/kWh for December 2014, and 24¢/kWh for January 2015.

Operating the former Massachusetts Electric Company and Nantucket Electric Company utilities, National Grid serves 1.2 million gas and electric customers in 168 Massachusetts communities.