2001 No. 55

WEIGHTS AND MEASURES

The Units of Measurement Regulations 2001

Made

Laid before Parliament

Coming into force

The Secretary of State, being a Minister designated1 for the purposes of section 2(2) of the European Communities Act 19722 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:—

Citation and commencement1

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

Interpretation2

In these Regulations—

  • “the Act” means the Weights and Measures Act 19853, and

  • “the Regulations” means the Units of Measurement Regulations 19864.

Amendment of the Act3

1

The Act shall be amended as follows.

2

In section 8(5A)5, after the words “the use for trade” there shall be inserted “up to and including 31 December 2009,”.

Amendment of the Regulations4

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:

Units used with the SI, whose values in SI are obtained experimentally4

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 HowellsParliamentary Under-Secretary of State for Consumers and Corporate Affairs,Department of Trade and Industry

(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.