National Grid officials are alerting electric customers about a new scam.

"Individuals claiming to work for National Grid" are calling customers to "demand payment on past due balances for electric accounts and threaten customers that their service will immediately be shut-off for non-payment," the utility said Tuesday in a presss release.

"In some cases the caller also tells the customer that they may have a faulty meter that is dangerous and in need of replacing for a substantial fee. Callers are being directed to make an immediate, over-the-phone payment in order to keep their power on."

National Grid is asking customers receiving such calls to contact its Customer Contact Center at 1-800-322-3223.