<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                     Year  Ended  December  31,
                                     June 30,    ------------------------------------------------------
                                      1998           1997       1996       1995       1994       1993
                                  -------------  ---------- ---------- ---------- ---------- ----------
<S>                               <C>            <C>        <C>        <C>        <C>        <C>
Net income                             $90,138    $105,709   $116,187   $117,488   $108,310   $111,076
                                  -------------  ---------- ---------- ---------- ---------- ----------

Income taxes                            60,131      72,155     78,340     75,540     67,613     67,102
                                  -------------  ---------- ---------- ---------- ---------- ----------
Fixed charges: 
   Interest on long-term debt
     including amortization of
     discount, premium and
     expense                            80,463      78,350     69,329     65,572     61,128     62,651
   Other interest                       10,845      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                96,995      96,872     83,235     75,925     70,464     71,896
                                  -------------  ---------- ---------- ---------- ---------- ----------

Nonutility capitalized interest            (53)       (208)      (311)      (304)      (256)      (246)
                                  -------------  ---------- ---------- ---------- ---------- ----------

Earnings before income taxes
   and fixed charges                  $247,211    $274,528   $277,451   $268,649   $246,131   $249,828
                                  =============  ========== ========== ========== ========== ==========

Fixed charges                          $96,995     $96,872    $83,235    $75,925    $70,464    $71,896

Preferred dividend requirements          7,275       7,556     14,961     16,185     15,948     14,803
                                  -------------  ---------- ---------- ---------- ---------- ----------

                                      $104,270    $104,428    $98,196    $92,110    $86,412    $86,699
                                  =============  ========== ========== ========== ========== ==========

Ratio of earnings to fixed charges
   and preferred dividends                2.37        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.


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