# The Meters (Certification) Regulations 1990, Paragraph 10: Insulation property test


Each meter shall be tested to demonstrate that the insulation of the meter is of a sufficient standard to enable the meter to operate safely and correctly in the conditions in which it could reasonably be expected to be installed and operated.
TABLE 1
Influence quantities
Reference value
Tolerance
Ambient temperature
Reference temperature or, if not indicated, 23°C.
>15°C to <30°C
Meter position
Vertical
±3°
Voltage
Reference voltage
±1.5%
Frequency
Reference frequency 50Hz
±0.5%
Voltage and current waveform
Sinusoidal form
Distortion factor <5%
External magnetic induction at the reference frequency (paragraph 5.4)
Zero
Induction value that does not produce a relative error variation of more than& ±0.3%
TABLE 2
Test load in terms of marked current
Test No. & load
Power factor
Basic/maximum
Maximum continuous
Long range
Short range
Meter type
Polyphase meter load
Note 1 Where a range is given, any value within that inclusive range may be selected.
Note 2 For maximum continuously rated prepayment meters, the low load test value may be twice the value shown.
Note 3 For test no. 4 & 6, the inductive power factor shall be between 0.45 and 0.55 inclusive.
1 (high)
1
Imax
100%
100%–200% (Note 1)
100%–125% (Note 1)
Single & polyphase
Balanced
2 (intermediate)
1
Ib or 125%IB
Any load between 25%–75% of the value specified for Test No. 1
Single & polyphase
Balanced
3 (low)
1
5%Ib
1.67% (note 2)
5%
5%
Single & polyphase
Balanced
4 (inductive)
0.5
Ib or Imax
100%
The same value selected for Test No. 1
Single & polyphase
Balanced
5 (element)
1
Ib
100%
The same value selected for Test No. 1
Polyphase
One phase loaded in turn
6 (inductive) (element)
0.5
Ib
100%
The same value selected for Test No. 1
Polyphase
One phase loaded in turn
7 (starting-current)
1
0.5%Ib to 1.0%Ib
0.5% to 1.0%
0.5% to 1.0%
0.5% to 1.0%
Single & polyphase
Balanced

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Source: https://www.legislation.gov.uk/uksi/1990/792/schedule/1/paragraph/10 (the official version)
Page: https://openlegislation.uk/meters-certification-regulations-1990/schedule-1/paragraph-10
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.