<ARTICLE> UT
<LEGEND>
This schedule contains summary financial information extracted from the
balance sheet, statement of income and statement of cash flows contained in
Form 10-K of Commonwealth Energy System for the fiscal year ended December 31,
1998 and is qualified in its entirety by reference to such financial
statements.
</LEGEND>
<CIK> 0000071304
<NAME> COMMONWEALTH ENERGY SYSTEM
<MULTIPLIER> 1,000
       
                            
<FISCAL-YEAR-END>              DEC-31-1998
<PERIOD-END>                   DEC-31-1998
<PERIOD-TYPE>                         YEAR
<BOOK-VALUE>                      PER-BOOK
<TOTAL-NET-UTILITY-PLANT>        1,019,324
<OTHER-PROPERTY-AND-INVEST>         14,031
<TOTAL-CURRENT-ASSETS>             285,711
<TOTAL-DEFERRED-CHARGES>           271,583
<OTHER-ASSETS>                     172,239
<TOTAL-ASSETS>                   1,762,888
<COMMON>                            43,081
<CAPITAL-SURPLUS-PAID-IN>          112,170
<RETAINED-EARNINGS>                294,341
<TOTAL-COMMON-STOCKHOLDERS-EQ>     449,592
<PREFERRED-MANDATORY>               11,380
<PREFERRED>                              0
<LONG-TERM-DEBT-NET>               385,602
<SHORT-TERM-NOTES>                       0
<LONG-TERM-NOTES-PAYABLE>            2,000
<COMMERCIAL-PAPER-OBLIGATIONS>           0
<LONG-TERM-DEBT-CURRENT-PORT>       57,123
<PREFERRED-STOCK-CURRENT>              820
<CAPITAL-LEASE-OBLIGATIONS>         10,982
<LEASES-CURRENT>                     1,340
<OTHER-ITEMS-CAPITAL-AND-LIAB>     844,049
<TOT-CAPITALIZATION-AND-LIAB>    1,762,888
<GROSS-OPERATING-REVENUE>          980,115
<INCOME-TAX-EXPENSE>                26,253
<OTHER-OPERATING-EXPENSES>         865,002
<TOTAL-OPERATING-EXPENSES>         891,255
<OPERATING-INCOME-LOSS>             88,860
<OTHER-INCOME-NET>                  12,453
<INCOME-BEFORE-INTEREST-EXPEN>     101,313
<TOTAL-INTEREST-EXPENSE>            46,909
<NET-INCOME>                        54,404
<PREFERRED-STOCK-DIVIDENDS>            930
<EARNINGS-AVAILABLE-FOR-COMM>       53,474
<COMMON-STOCK-DIVIDENDS>            34,928
<TOTAL-INTEREST-ON-BONDS>           37,435
<CASH-FLOW-OPERATIONS>              81,949
<EPS-PRIMARY>                         2.48
<EPS-DILUTED>                         2.48