South Carolina Electric & Gas is requesting another rate hike to help pay for construction of two new nuclear units north of Columbia.

The Cayce-based utility has asked the S.C. Public Service Commission to approve an overall 2.7 percent increase that would take effect in October.

Rates for residential customers would rise 2.83 percent, or $3.58, to $130.32 per month for each 1,000 kilowatt hours of electricity used.

Rates for small and medium commercial users would go up 2.67 percent, and for large commercial and industrial customers, the bill would rise 2.49 percent.

SCE&G and state-owned utility Santee Cooper are building two nuclear electric-generating units at the site of the V.C. Summer Nuclear Station near Jenkinsville.

The first unit is expected to come online in 2016, with the second to follow in 2019, pending approval by the Nuclear Regulatory Commission.

SCE&G said that paying the financing expenses while construction is ongoing, as opposed to waiting until the project is completed, lowers the cost of building the units by about $1 billion.

That in turn would reduces the amount customers will pay through rates for such things as the cost of capital, depreciation, property taxes and insurance associated with the project.

SCE&G estimates that paying during the constriction phase will save customers at least $4 billion in electric rates over the life of the new units.

To pay for the new nuclear units, rate increases are expected to average a little more than 2 percent annually through 2019, but will vary year to year based on actual construction expenditures incurred.

Reach Warren L. Wise at 937-5524.