# The Meters (Certification) Regulations 1990, Paragraph 8: Polyphase meters


(1) 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.
(2) When testing polyphase meters, 3 single phase or 2 single phase working standard precision kilowatt-hour meters or working standard watthour meters as appropriate may be used instead of polyphase working standard instruments.

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Source: https://www.legislation.gov.uk/uksi/1990/792/schedule/1/paragraph/8 (the official version)
Page: https://openlegislation.uk/meters-certification-regulations-1990/schedule-1/paragraph-8
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.