Aug 7 (Reuters) - Electric and gas utility NiSource ( NI )

beat second-quarter profit estimates on Wednesday as

lower costs helped counter the impact of weak gas sales.

U.S. natural gas futures have fallen about 17% so far

this year, helping utilities such as NiSource ( NI ) reduce their fuel

costs.

Lower fuel costs helped bring down the company's overall

operating expenses by nearly 8% in the second quarter.

NiSource ( NI ) serves nearly 4 million natural gas and electric

customers across six U.S. states through subsidiaries Columbia

Gas and NIPSCO.

Operating revenue from its Columbia Gas operations fell

nearly 7% to $490.5 million for the quarter from a year ago.

This included a $6.9 million weather-related hit.

The company posted an adjusted profit of 21 cents per share

in the second quarter, exceeding analysts' average estimate of

16 cents, according to LSEG data.

NiSource ( NI ) reaffirmed its full-year adjusted profit forecast

of $1.70 to $1.74 per share, compared with expectations of

$1.72.