The Meters (Certification) Regulations 1998

Insulation property test

10.  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 of 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 number and load	Power factor	Basic/maximum	Maximum continuous	Long range	Short range	Meter type	Polyphase meter load
1 (high)	1	Imax	100%	100%–200% (Note 1)	100%–125% (Note 1)	Single and polyphase	Balanced
2 (intermediate)	1	Ib or 125%Ib	Any load between 25%–75% of the value specified for test number 1 (Note 1)			Single and polyphase	Balanced
3 (low)	1	5%Ib	1.67% (Note 2)	5%	5%	Single and polyphase	Balanced
4 (inductive)	0.5 (Note 3)	Ib or Imax	100%	The same value selected for test number 1		Single and polyphase	Balanced
5 (element)	1	Ib	100%	The same value selected for test number 1		Polyphase	One phase loaded in turn
6 (inductive) (element)	0.5 (Note 3)	Ib	100%	The same value selected for test number 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 and polyphase	Balanced

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 numbers 4 and 6, the inductive power factor shall be between 0.45 and 0.55 inclusive.