Electrical question

[Aquattro]

A question for anyone that knows more about electrical than I, which should be everybody! Recently, say last three weeks, the power bar my lights are plugged into trips about 5 hours into running. Tried a new bar, same thing. This setup has been running unchanged for some time, say 5 or 6 months, and only recently this has happened. Nothing has been added. Would cooling for the ballasts help? although it ran fine in the hottest part of last summer.
Thoughts?