<PAGE>
 
                                                                    Exhibit 12-B

                        Delmarva Power & Light Company

          Ratio of Earnings to Fixed Charges and Preferred Dividends
                            (Dollars in Thousands)

<TABLE>
<CAPTION>
                                           12 Months
                                             Ended
                                           March 31,                            Year Ended December 31,
                                                          ---------------------------------------------------------------------
                                             1998             1997          1996          1995          1994          1993
                                       ------------------ ------------- ------------- ------------- ------------- -------------
<S>                                    <C>                <C>           <C>           <C>           <C>           <C>
Net income                                      $75,060       $105,709      $116,187      $117,488      $108,310      $111,076
                                       ------------------ ------------- ------------- ------------- ------------- -------------

Income taxes                                     51,782         72,155        78,340        75,540        67,613        67,102
                                       ------------------ ------------- ------------- ------------- ------------- -------------

Fixed charges:
    Interest on long-term debt
      including amortization of
      discount, premium and
      expense                                    79,587         78,350        69,329        65,572        61,128        62,651
    Other interest                               12,562         12,835        12,516        10,353         9,336         9,245
    Preferred dividend require-
      ments of a subsidiary
      trust                                       5,687          5,687         1,390           -             -             -
                                       ------------------ ------------- ------------- ------------- ------------- -------------
      Total fixed charges                        97,836         96,872        83,235        75,925        70,464        71,896
                                       ------------------ ------------- ------------- ------------- ------------- -------------

Nonutility capitalized interest                    (132)          (208)         (311)         (304)         (256)         (246)
                                       ------------------ ------------- ------------- ------------- ------------- -------------

Earnings before income taxes
    and fixed charges                          $224,546       $274,528      $277,451      $268,649      $246,131      $249,828
                                        =================  ============  ============  ============  ============  ============

Fixed charges                                  $ 97,836       $ 96,872      $ 83,235      $ 75,925      $ 70,464      $ 71,896

Preferred dividend requirements                   7,371          7,556        14,961        16,185        15,948        14,803
                                       ------------------ ------------- ------------- ------------- ------------- -------------

                                               $105,207       $104,428       $98,196       $92,110       $86,412       $86,699
                                        =================  ============  ============  ============  ============  ============

Ratio of earnings to fixed charges
    and preferred dividends                        2.13           2.63          2.83          2.92          2.85          2.88
</TABLE> 

For purposes of computing the ratio, earnings are net income plus income taxes
and fixed charges, less nonutility capitalized interest. Fixed charges consist
of interest on long- and short-term debt, amortization of debt discount,
premium, and expense, dividends on preferred securities of a subsidiary trust,
plus the interest factor associated with the Company's major leases, and one-
third of the remaining annual rentals. Preferred dividend requirements represent
annualized preferred dividend requirements multiplied by the ratio that pre-tax
income bears to net income.

                                     -19-