(Adds details about the line, market reaction)
By Nia Williams
CALGARY, Alberta, May 6 (Reuters) - Enbridge Inc's 796,000 barrel per day Line 4, which carries crude oil from Edmonton, Alberta, to Clearbrook, Minnesota, was shut on Tuesday after a power outage, a company spokesman said.
Enbridge spokesman Graham White said the power outage stemmed from a failure on SaskPower's transmission line feeding two pump stations in Saskatchewan, and Enbridge would know more about start-up times by Wednesday morning.
Two market sources in Calgary said Enbridge had told shippers power should be restored late on Wednesday.
Line 4 transports heavy crude and is part of the Enbridge Mainline system which carries the bulk of Canadian crude exports to the United States.
Heavy crude prices weakened in response to the shutdown. Western Canada Select heavy blend for June delivery last traded at $18.25 per barrel below the West Texas Intermediate benchmark, according to Shorcan Energy brokers.
On Monday WCS settled at $17.15 per barrel below WTI. (Additional reporting by Scott Haggett; Editing by David Gregorio and Mohammad Zargham)