Mike Dolt Enterprises
Mike Dolt Enterprises
User: apelkner, Location: Massachusetts
Asked on: Monday, April 11, 2011 at 10:26 am EDT
Answered on: Tuesday, May 14, 2024 at 4:02 am EDT
Question: Hi,I have a client with 3-phase 250V 50A refrigerated truck trailers with locking type california style plugs who wants receptacles at the loading dock.The building has 120/208V and 277/480V panels. I'm not familiar with 250V. Is there a way they can get this from existing panels or is there a different type of panel that will need to be installed?Thanks,Amy
Converting Existing Panels to 250V 277/480V Panel
Not suitable for direct conversion to 250V.
120/208V Panel
Requires the use of a transformer to boost the voltage to 250V.
Transformer Considerations
Transformer Rating
50A capacity (trailer current)
Transformer Voltage
208V primary to 250V secondary
Transformer Type
Dry-type or liquid-filled (depending on installation location)
Receptacle Installation
Install a NEMA L22-20 3-phase 250V 50A locking receptacle at the loading dock. Provide appropriate cable and wiring for the amperage and voltage requirements.
Other Considerations
Check local electrical codes for specific requirements regarding 250V installations. Ensure proper grounding and bonding of the equipment and system. Train personnel on the safe operation of the 250V system.
Recommendation
Given the limited options for converting existing panels to 250V, it is recommended to install a
dedicated transformer to provide the necessary voltage for the refrigerated trailers. This ensures a reliable and safe power supply while avoiding potential issues with other equipment connected to the existing panels. Flag for review