{
  "url": "https://openlegislation.uk/meters-certification-regulations-northern-ireland-1998/schedule-3/paragraph-9",
  "json_url": "https://openlegislation.uk/meters-certification-regulations-northern-ireland-1998/schedule-3/paragraph-9.json",
  "legislation": "nisr/1998/444",
  "legislation_title": "Meters (Certification) Regulations (Northern Ireland) 1998",
  "legislation_url": "https://openlegislation.uk/meters-certification-regulations-northern-ireland-1998",
  "path": "schedule/3/paragraph/9",
  "kind": "paragraph",
  "number": "9",
  "heading": "Margins of error",
  "text": "(1) The maximum 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% for test numbers 1, 2, 3 and 4 in Table 2.\n(2) The maximum error permitted for both single phase and polyphase transformer operated meters, when tested without transformers connected, shall not exceed plus or minus 1.4% for test numbers 1, 2, 3 and 4 given in Table 2.\n(3) The maximum error permitted for polyphase whole current meters and transformer operated meters, when tested with transformers connected, shall not exceed plus 2% or minus 3% for test numbers 5 and 6 given in Table 2.\n(4) The maximum error permitted for polyphase transformer operated meters, when tested without transformers connected, shall not exceed plus 1.5% or minus 2.5% for test numbers 5 and 6 given in Table 2.\n(5) Where current and voltage transformers, which are intended to be used with meters, are not tested connected to a meter then the total error of the transformers at any load point throughout the rated range shall not exceed 0.5%.\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 50Hz\n± 0.5%\nVoltage and current waveform\nSinusoidal form\nDistortion factor <5%\nExternal magnetic induction at the reference frequency\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\nNote 1\nWhere a range is given, any value within that inclusive range may be selected.\nNote 2\nFor maximum continuously rated prepayment meters, the low load test value may be twice the value shown.\nNote 3\nFor Test Numbers 4 and 6, the inductive power factor shall be between 0.45 and 0.55 inclusive.\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\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",
  "extent": "N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "I",
      "label": "I1",
      "text": "Sch. 3 para. 9 in operation at 1.2.1999, see reg. 1"
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/nisr/1998/444/schedule/3/paragraph/9",
    "retrieved_at": "2026-10-29T02:21:52.995521+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."
}