Newfoundland and Labrador's two power utilities will start giving refunds Wednesday to 292,000 customers who were charged too much over a period that spanned six years.

The refunds will be made to customers of both Newfoundland Power and Newfoundland and Labrador Hydro, and involve overpayments charged between 2007 and 2013.

Michele Coughlan, a communications official with Newfoundland Power, says customers should not be alarmed if they do not find a cheque in their mailbox. 

"The refund for each customer will first be credited against any existing balance on their electricity account," she told CBC News in a statement. 

For any remaining amount, she said, a cheque will be issued to the customer whose name appears on the electricity bill.

The refund for about 200,000 eligible customers will be reflected on the first electricity bill after Feb. 13, 2017.

But Newfoundland Power also has to track down 92,000 who no longer hold any type of account with the company. The work of tracking them down will start in April. 

Some customers will receive more than $400

Every customer who paid a bill between Jan 1, 2007 and Aug. 31, 2013 is eligible for a refund. Newfoundland Power says ratepayers with electric heat will be refunded an average of $5.58 for every month they paid too much.

Under that scenario, a customer who was overcharged for the full 80 months will be eligible for a $446.40.

However, customers who used less electric heat during that period will receive a small refund. 

For those without electric heat at home, the refund will be approximately $3.05 for each eligible month.

After taxes, the company indicated the total amount to be refunded to customers will be approximately $154 million.

Retail customers of Newfoundland and Labrador Hydro are also eligible. 

The refund comes from overpayments made to Newfoundland and Labrador Hydro starting in 2007, when the utility company saw industrial usage drop. The Crown corporation wound up spending less than forecast on fuel.

Newfoundland Power says customers receiving a refund should allow up to 10 business days for delivery.