2001 No. 55
WEIGHTS AND MEASURES
The Units of Measurement Regulations 2001
Made 10th January 2001
Laid before Parliament 15th January 2001
Coming into force 8th February 2001

The Secretary of State, being a Minister designated for the purposes of section 2(2) of the European Communities Act 1972 in relation to units of measurement to be used for economic, health, safety or administrative purposes, in exercise of the powers conferred by that sub-section, hereby makes the following Regulations:—
S.I.1976/897.
1972 c. 68.

1 Citation and commencement
These Regulations may be cited as the Units of Measurement Regulations 2001 and shall come into force on 8th February 2001.

2 Interpretation
In these Regulations—
“the Act” means the Weights and Measures Act 1985, and
“the Regulations” means the Units of Measurement Regulations 1986.
1985 c. 72.
S.I.1986/1082, amended by S.I.1994/2867 and S.I.1995/1804.

3 Amendment of the Act
1 The Act shall be amended as follows.
2 In section 8(5A), after the words “the use for trade” there shall be inserted “up to and including 31 December 2009,”.
section 8(5a) of the Weights and Measures Act 1985 was inserted by the Units of Measurement Regulations 1994.

4 Amendment of the Regulations
1 The Regulations shall be amended as follows.
2 In regulation 7, after the words “specified circumstances”, there shall be inserted “up to and including 31 December 2009”.
3 In paragraph 1 of Schedule 1, the text under the table which appears beneath the heading “Special name and symbol of the SI unit of temperature for expressing Celsius temperature.” shall be replaced as follows:

“Celsius temperature t is defined as the difference t = T − To between the two thermodynamic temperatures T and To where To = 273, 15 K. An interval or difference of temperature may be expressed either in kelvins or in degrees Celsius. The unit “degree Celsius” is equal to the unit “kelvin”.”

.
4 In paragraph 2 of Schedule 1, the definitions of the SI supplementary units shall be replaced as follows:

“Unit of plane angle
The radian is the angle between two radii of a circle which cut off on the circumference an arc equal in length to the radius.
(International standard ISO 31-1: 1992. British Standard BS 5775-1:1993)

Unit of solid angle
The steradian is the solid angle of a cone which, having its vertex in the centre of a sphere, cuts off on the surface of the sphere an area equal to that of a square with sides of length equal to the radius of the sphere.
(International standard ISO 31-1: 1992. British Standard BS 5775-1:1993).”

5 Paragraph 4 of Schedule 1 shall be replaced by the following:

“4 Units used with the SI, whose values in SI are obtained experimentally
Quantity			
Energy	Electronvolt	eV	The electron volt is the kinetic energy acquired by an electron in passing through a potential difference of 1 volt in vacuum.
Mass	Unified atomic mass unit	u	The unified atomic mass unit is equal to 1/12 of the mass of an atom of the nuclide 12C
Note: The prefixes and their symbols listed in Schedule 2 may be used in conjunction with these two units and with their symbols.			”

.
6 In Schedule 2, the table below the heading shall be replaced by the following:

“Factor	Prefix	Symbol	Factor	Prefix	Symbol
1024	yotta	Y	10−1	deci	d
10 21	zetta	Z	10− 2	centi	c
10 18	exa	E	10−3	milli	m
10 15	peta	P	10− 6	micro	μ
10 12	tera	T	10−9	nano	n
109	giga	G	10−12	pico	p
106	mega	M	10−15	femto	f
103	kilo	k	10− 18	atto	a
102	hecto	h	10− 21	zepto	z
10 1	deca	da	10−24	yocto	y”

.
Kim Howells Parliamentary Under-Secretary of State for Consumers and Corporate Affairs, Department of Trade and Industry 10th January 2001

(This note is not part of the Regulations)
These Regulations implement the amendments made by Directive 1999/103/EC of the European Parliament and of the Council (OJ L34, 9.2.2000 p.17) to Council Directive 80/181/EEC (OJ L39, 15.2.80, p40) (“the Directive”) which relates to the use of units of measurement for economic, public health, public safety or administrative purposes.
These Regulations amend the Weights and Measures Act 1985 by inserting a deadline of 31 December 2009 for the end of the authorised use of supplementary indications in conjunction with metric units. The Regulations amend the Units of Measurement Regulations 1986 by inserting the same deadline. The Regulations also make various technical changes in order to bring the 1986 Regulations in line with the list of SI prefixes to be used for multiples and submultiples of SI units which was agreed at the 19th Conférence Générale des Poids et Mesures (1991) and the revised principles and rules regarding quanitities and units as laid down in the international standard ISO 31. ISO 31 is reproduced in BS 5775 (fourteen parts):
ISBN Number		
BS 5775
	Part 0	058022194 6
	Part 1	058021995 X
	Part 2	058021996 8
	Part 3	058021997 6
	Part 4	058021998 4
	Part 5	058021999 2
	Part 6	058022000 1
	Part 7	058022001 X
	Part 8	058022195 4
	Part 9	058022002 8
	Part 10	058022003 6
	Part 11	058021799 X
	Part 12	058022004 4
	Part 13	058022005 2
Copies of the above can be obtained from any of the sales outlets operated by the British Standards Institute (BSI) or by post from BSI at Milton Keynes.
These Regulations are brought into force on 8th February 2001.
A Regulatory Impact Assessment of the costs and benefits which will result from these Regulations has been prepared. Copies have been placed in the libraries of both Houses of Parliament and can also be obtained from the Consumer Affairs Directorate of the Department of Trade and Industry, Room 460, 1 Victoria Street, London SW1H 0ET.