Within hours the country suffered yet another total collapse of the National Electric System (SEN). They are caused when the country is unable to generate enough electricity to meet demand, or by a localized failure. In recent weeks routine interruptions have exceeded 20 hours in Havana and reached up to 72 consecutive hours in other provinces. Blackouts in Havana rose from an average of four hours to 18 hours a day. There are days that go by, the full 24 hours, without electricity.