Paragraph 8 Polyphase meters

Every polyphase meter shall be tested on a circuit having a phase relationship for which the meters were designed. However, three phase, four wire polyphase meters may be tested without current in the neutral conductor.

When testing polyphase meters, it is permissible to use, as appropriate, 3 single phase or 2 single phase working standard precision kilowatt-hour meters or working standard watthour meters instead of polyphase working standard instruments.