I work for a company that is going through a big growth phase. In dealing with all this growth, we have had to rent additional HVAC equipment to handle the additional heat load of the plant. Now my question is this. How long can temporary power cables be used to power these units. The HVAC rental company has used and ran 4O welding cables for the individual 3phase conductors from the power source, to the equipment. They have used twist lock welding cable connectors to join the cables together. Now my question is this. How long can this setup be in place before something permanent must be installed? Two of the units have been in place for two years now. Can I force the issue with a code or standard to get something permanent installed? If so, what are the standards or codes to use?