Atlantic City Electric on Thursday asked New Jersey regulators to approve a $70.2 million rate increase that would boost a typical residential customer's monthly bill by $9, from $136.90 to $145.90, or 6.6 percent.

ACE, which serves 550,000 customers in South Jersey, filed the 928-page rate request with the New Jersey Board of Public Utilities, saying the increase was justified by the need for upgrades to its infrastructure.

Like many other utilities, ACE said it needs higher rates to cover its costs in a climate of declining sales caused by greater efficiency and customers who have installed solar systems.

The utility said its sales had declined by 6.2 percent from 2011, and that they were projected to decline by 2 percent more in 2017-2018.

The rate-increase request includes a $2 boost in the fixed monthly charge for residential customers, which is now set at $4.44. That would shift more of the utility's costs onto customers regardless of how much power they use, an industry trend.

Additional revenue is needed to cover infrastructure costs, the utility said. It noted that it had spent about $160 million to maintain and strengthen its power-delivery system in 2016 and $25 million on tree trimming and vegetation management along its 1,900 miles of power lines, a $9 million increase over 2015.

If approved by the BPU, the increase would go into effect in nine months.