By Scott Haggett

CALGARY, Alberta (Reuters) - Enbridge Inc
lowered capacity on its 490,000 barrel-per-day Line 5, the main
alternative to its Michigan pipeline that ruptured last month,
but said Friday it doesn't expect the move to reduce
shipments on the key line.

Enbridge cut rates on the line to Sarnia, Ontario, in order
to carry out additional safety checks after a 5-foot gash
opened in the side of the 190,000 barrel per day Line 6B,
spilling more than 800,000 gallons of oil sands crude into a
Michigan river system.

However, the company said that, despite the capacity cut,
it can meet current commitments for shipments on the line,
which carries light oil and synthetic crude from the oil sands,
as well as natural gas liquids.

"We have reduced the operating capacity of Line 5," said
Jennifer Varey, a spokeswoman for Enbridge. "But all current
volumes allocated can be accommodated."

Varey said the company has not resorted to rationing space
on its lines but could not say how much capacity was being cut
or the duration of the reduction.

"We don't anticipate it is going to affect the existing
throughput schedule for August," she said. "We're working to
... provide as much capacity to shippers as possible."

Lines 5 and 6B are part of Enbridge's massive pipeline
system that carries the bulk of Canadian crude oil exports to
the United States, and serve refineries in the U.S. upper
Midwest and southern Ontario, which produce more than 700,000
barrels of fuel a day.

Three of the refineries that depend on oil from the broken
line have had to cut production. United Refining Co, which
which runs a 70,000 barrel a day plant in Warren, Pennsylvania,
said Friday it continues to operate at reduced rates while
they wait for Enbridge to reopen the damaged crude oil line.

The privately held company said that it has other sources
of crude for its refinery but the types and the quantity of the
crude are not as favorable economically as that carried in
Enbridge's Line 6B.

Enbridge filed a revised restart plan for the ruptured line
Friday with the U.S. Department of Transportation's Pipeline
and Hazardous Materials Safety Administration.

The regulator said it plans to look over the filing.

"PHMSA will scrutinize Enbridge's revised plan for all
safety concerns and to ensure it provides for the protection of
the environment," a PHSMA spokesperson said in an email.

"The agency will not accept a plan from Enbridge until we
are confident that the company has met all of our safety
concerns."

Earlier this week the regulator rejected the company's plan
to resume oil shipments because it wants Enbridge to
investigate at least four other sections of line where testing
showed anomalies similar to one at the site of the rupture, as
well as to conduct pressure tests.

Varey said Enbridge has also stepped up safety testing on
the rest of its system following the Line 6B rupture.

"In light of recent incidents we're being extremely
cautious," she said.

Enbridge shares rose 46 Canadian cents to C$50.90 on the
Toronto Stock Exchange Friday while its U.S. affiliate,
Enbridge Energy Partners rose 98 cents to $53.93 in New
York.

($1=$1.04 Canadian)
(Additional reporting by Janet McGurty; editing by Rob
Wilson)