<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,
1997 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-31-1997
<PERIOD-END>                   DEC-31-1997
<PERIOD-TYPE>                         YEAR
<BOOK-VALUE>                      PER-BOOK
<TOTAL-NET-UTILITY-PLANT>        1,049,908
<OTHER-PROPERTY-AND-INVEST>         13,767
<TOTAL-CURRENT-ASSETS>             212,986
<TOTAL-DEFERRED-CHARGES>           208,389
<OTHER-ASSETS>                           0
<TOTAL-ASSETS>                   1,485,050
<COMMON>                            43,063
<CAPITAL-SURPLUS-PAID-IN>          111,912
<RETAINED-EARNINGS>                275,795
<TOTAL-COMMON-STOCKHOLDERS-EQ>     430,770
<PREFERRED-MANDATORY>               12,200
<PREFERRED>                              0
<LONG-TERM-DEBT-NET>               364,311
<SHORT-TERM-NOTES>                       0
<LONG-TERM-NOTES-PAYABLE>           94,075
<COMMERCIAL-PAPER-OBLIGATIONS>           0
<LONG-TERM-DEBT-CURRENT-PORT>       26,653
<PREFERRED-STOCK-CURRENT>              820
<CAPITAL-LEASE-OBLIGATIONS>         12,272
<LEASES-CURRENT>                     1,229
<OTHER-ITEMS-CAPITAL-AND-LIAB>     542,720
<TOT-CAPITALIZATION-AND-LIAB>    1,485,050
<GROSS-OPERATING-REVENUE>        1,041,744
<INCOME-TAX-EXPENSE>                31,040
<OTHER-OPERATING-EXPENSES>         923,054
<TOTAL-OPERATING-EXPENSES>         954,094
<OPERATING-INCOME-LOSS>             87,650
<OTHER-INCOME-NET>                   2,601
<INCOME-BEFORE-INTEREST-EXPEN>      90,251
<TOTAL-INTEREST-EXPENSE>            40,350
<NET-INCOME>                        49,901
<PREFERRED-STOCK-DIVIDENDS>            988
<EARNINGS-AVAILABLE-FOR-COMM>       48,913
<COMMON-STOCK-DIVIDENDS>            34,068
<TOTAL-INTEREST-ON-BONDS>           33,572
<CASH-FLOW-OPERATIONS>             107,551
<EPS-PRIMARY>                         2.27
<EPS-DILUTED>                         2.27