<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,
                                                  March 31,    --------------------------------------------------------------------
                                                    1999          1998          1997           1996          1995           1994
                                                 ---------     ---------     ---------      ---------      ---------      ---------
<S>                                              <C>           <C>           <C>            <C>            <C>            <C>      
Net income                                       $ 152,880     $ 112,410     $ 105,709      $ 116,187      $ 117,488      $ 108,310
                                                 ---------     ---------     ---------      ---------      ---------      ---------

Income taxes                                        98,142        72,276        72,155         78,340         75,540         67,613
                                                 ---------     ---------     ---------      ---------      ---------      ---------

Fixed charges:
  Interest on long-term debt
    including amortization of
    discount, premium and
    expense                                         80,729        81,132        78,350         69,329         65,572         61,128
  Other interest                                     7,982         9,328        12,835         12,516         10,353          9,336
  Preferred dividend requirements 
    of a subsidiary trust                            5,688         5,688         5,687          1,390             --             --
                                                 ---------     ---------     ---------      ---------      ---------      ---------
    Total fixed charges                             94,399        96,148        96,872         83,235         75,925         70,464
                                                 ---------     ---------     ---------      ---------      ---------      ---------

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

Earnings before income taxes
  and fixed charges                              $ 345,421     $ 280,834     $ 274,528      $ 277,451      $ 268,649      $ 246,131
                                                 =========     =========     =========      =========      =========      =========

Fixed charges                                    $  94,399     $  96,148     $  96,872      $  83,235      $  75,925      $  70,464

Preferred dividend requirements                      7,124         7,150         7,556         14,961         16,185         15,948
                                                 ---------     ---------     ---------      ---------      ---------      ---------

                                                 $ 101,523     $ 103,298     $ 104,428      $  98,196      $  92,110      $  86,412
                                                 =========     =========     =========      =========      =========      =========

Ratio of earnings to fixed charges
  and preferred dividends                             3.40          2.72          2.63           2.83           2.92           2.85
</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 DPL'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 income.