{
  "url": "https://openlegislation.uk/meters-certification-regulations-1998/schedule-3/paragraph-9",
  "json_url": "https://openlegislation.uk/meters-certification-regulations-1998/schedule-3/paragraph-9.json",
  "legislation": "uksi/1998/1566",
  "legislation_title": "The Meters (Certification) Regulations 1998",
  "legislation_url": "https://openlegislation.uk/meters-certification-regulations-1998",
  "path": "schedule/3/paragraph/9",
  "kind": "paragraph",
  "number": "9",
  "heading": "Margins of error",
  "text": "(1) The error permitted for—\n(a) single phase and polyphase whole current meters and\n(b) single phase and polyphase transformer operated meters when tested with transformers connected\nshall not exceed plus or minus 1.9 per cent. for test numbers 1, 2, 3 and 4 in table 2.\n(2) The error permitted for both single phase and polyphase transformer operated meters, when tested without transformers connected, shall not exceed plus or minus 1.4 per cent. for test numbers 1, 2, 3 and 4 given in table 2.\n(3) The error permitted for polyphase whole current meters and transformer operated meters, when tested with transformers connected, shall not exceed plus 2 per cent. or minus 3 per cent. for test numbers 5 and 6 given in table 2.\n(4) The error permitted for polyphase transformer operated meters, when tested without transformers connected, shall not exceed plus 1.5 per cent. or minus 2.5 per cent. for test numbers 5 and 6 given in table 2.\n(5) Where current and voltage transformers are intended to be used with meters and are not tested connected to a meter then the error of the transformers at any load point throughout the rated range shall not exceed 0.5 per cent.\nTABLE 1\nInfluence quantities\nReference value\nTolerance\nAmbient temperature\nReference temperature or, if not indicated, 23°C.\n±2°\nMeter position\nVertical\n±3°\nVoltage\nReference voltage\n±1.5%\nFrequency\nReference frequency of 50Hz\n±0.5%\nVoltage and current waveform\nSinusoidal form\nDistortion factor <5%\nExternal magnetic induction at the reference frequency (paragraph 5(5))\nZero\nInduction value that does not produce a relative error variation of more than ±0.3%\nTABLE 2\nTest load in terms of marked current\nTest number and load\nPower factor\nBasic/maximum\nMaximum continuous\nLong range\nShort range\nMeter type\nPolyphase meter load\n1 (high)\n1\nImax\n100%\n100%–200%(Note 1)\n100%–125% (Note 1)\nSingle and polyphase\nBalanced\n2 (intermediate)\n1\nIb or 125%Ib\nAny load between 25%–75% of the value specified for test number 1 (Note 1)\nSingle and polyphase\nBalanced\n3 (low)\n1\n5%Ib\n1.67% (Note 2)\n5%\n5%\nSingle and polyphase\nBalanced\n4 (inductive)\n0.5 (Note 3)\nIb or Imax\n100%\nThe same value selected for test number 1\nSingle and polyphase\nBalanced\n5 (element)\n1\nIb\n100%\nThe same value selected for test number 1\nPolyphase\nOne phase loaded in turn\n6 (inductive) (element)\n0.5 (Note 3)\nIb\n100%\nThe same value selected for test number 1\nPolyphase\nOne phase loaded in turn\nNote 1 Where a range is given, any value within that inclusive range may be selected.\nNote 2 For maximum continuously rated prepayment meters, the low load test value may be twice the value shown.\nNote 3 For test numbers 4 and 6, the inductive power factor shall be between 0.45 and 0.55 inclusive.",
  "extent": "E+W+S",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "I",
      "label": "I1",
      "text": "Sch. 3 para. 9 in force at 1.8.1998, see reg. 1"
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/uksi/1998/1566/schedule/3/paragraph/9",
    "retrieved_at": "2026-10-29T11:26:36.743610+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}