A major power failure and rain have marred Queensland's biggest Melbourne Cup day party at Eagle Farm.

Rain fell early in the day impacting on the expected crowd of 10,000 to 12,000 and then the power at the track went down just before race four at 12.50pm.

The running of the last five races were suspended until just after 3pm despite more rain falling for 30 minutes.

There was no television coverage available on course for the running of the Melbourne Cup and hundreds of people left the course to watch the race elsewhere.

Many others tried to access the big race on their mobile phones or lap top computers but they also froze because of the large number of users.

Officials were able to get a loud speaker in the enclosure so punters could hear the race.

Some other parts of the Ascot suburb which surrounds Eagle Farm also reported power failures.

Brisbane Race Club chairman Neville Bell said the general outage in the area had been most unfortunate and he apologised to patrons.

"Two fuses in the power box outside the course blew and it was a lot more complicated than at first thought to fix," Bell said.

"We made efforts to get a generator but we couldn't get a big enough one in time."

Bell said the club would hold a full inquiry into what happened.

Away from Eagle Farm, Cup day parties were held at 13 other racetracks and hundreds of venue across Queensland.