IMS the table in the NEC specifically allows the use of a fifty ampere receptacle on a forty ampere circuit. That is the practical thing to do when the load will be cord and plug connected because there is no source for forty ampere cords and plugs. -- Tom H
Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
The table in question is 210.24. I looked at several list of receptacle patterns, including the ones in the NEC Handbook, without finding one for forty amperes. -- Tom H
Tom Horne
"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison