<TABLE> <S> <C>
<PAGE>
<ARTICLE> UT
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED BALANCE SHEET AND STATEMENT OF INCOME FROM ACE'S 2/ND/ QUARTER 2000
10Q AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
<S> <C>
<PERIOD-TYPE> 6-MOS
<FISCAL-YEAR-END> DEC-31-2000
<PERIOD-START> JAN-01-2000
<PERIOD-END> JUN-30-2000
<BOOK-VALUE> PER-BOOK
<TOTAL-NET-UTILITY-PLANT> 977,235
<OTHER-PROPERTY-AND-INVEST> 113,600
<TOTAL-CURRENT-ASSETS> 286,921
<TOTAL-DEFERRED-CHARGES> 1,113,564
<OTHER-ASSETS> 67,796
<TOTAL-ASSETS> 2,559,116
<COMMON> 54,963
<CAPITAL-SURPLUS-PAID-IN> 493,007
<RETAINED-EARNINGS> 110,948
<TOTAL-COMMON-STOCKHOLDERS-EQ> 658,918
118,950
6,231
<LONG-TERM-DEBT-NET> 944,802
<SHORT-TERM-NOTES> 0
<LONG-TERM-NOTES-PAYABLE> 0
<COMMERCIAL-PAPER-OBLIGATIONS> 0
<LONG-TERM-DEBT-CURRENT-PORT> 10,075
0
<CAPITAL-LEASE-OBLIGATIONS> 10,886
<LEASES-CURRENT> 15,480
<OTHER-ITEMS-CAPITAL-AND-LIAB> 793,774
<TOT-CAPITALIZATION-AND-LIAB> 2,559,116
<GROSS-OPERATING-REVENUE> 445,135
<INCOME-TAX-EXPENSE> 4,134
<OTHER-OPERATING-EXPENSES> 386,044
<TOTAL-OPERATING-EXPENSES> 390,178
<OPERATING-INCOME-LOSS> 54,957
<OTHER-INCOME-NET> 3,016
<INCOME-BEFORE-INTEREST-EXPEN> 57,973
<TOTAL-INTEREST-EXPENSE> 42,287
<NET-INCOME> 15,686
1,065
<EARNINGS-AVAILABLE-FOR-COMM> 14,621
<COMMON-STOCK-DIVIDENDS> 33,655
<TOTAL-INTEREST-ON-BONDS> 0
<CASH-FLOW-OPERATIONS> 125,983
<EPS-BASIC> 0
<EPS-DILUTED> 0
</TABLE>
