BRITISH STANDARD
BS EN
50274:2002
Incorporating
corrigendum
July 2009
Low-voltage switchgear
and controlgear
assemblies —
Protection against
electric shock —
Protection against
unintentional direct
contact with hazardous
live parts
ICS 29.130.20
12&23<,1*:,7+287%6,3(50,66,21(;&(37$63(50,77('%<&23<5,*+7/$:
BS EN 50274:2002
National foreword
This British Standard is the UK implementation of
EN 50274:2002, incorporating corrigendum July 2009.
The UK participation in its preparation was entrusted by Technical
Committee PEL/17, Switchgear, controlgear and Hv-Lv co-ordination,
to Subcommittee PEL/17/3, Low voltage switchgear and controlgear
assemblies.
A list of organizations represented on this subcommittee can be
obtained on request to its secretary.
This publication does not purport to include all the necessary
provisions of a contract. Users are responsible for its correct
application.
Compliance with a British Standard cannot confer immunity
from legal obligations.
This British Standard was
published under the authority
of the Standards Policy and
Strategy Committee
on 23 July 2002
© BSI 2010
ISBN 978 0 580 68600 9
Amendments/corrigenda issued since publication
Date
Comments
31 January 2010
Implementation of CENELEC corrigendum July
2009. Text in Clause 4.5 amended
EN 50274
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2002
ICS 29.120.60
English version
Low-voltage switchgear and controlgear assemblies Protection against electric shock Protection against unintentional direct contact with hazardous live parts
Ensembles d'appareillage à basse tension Protection contre les chocs électriques Protection contre le contact direct
involontaire avec des parties actives
dangereuses
NiederspannungsSchaltgerätekombinationen Schutz gegen elektrischen Schlag Schutz gegen unabsichtliches direktes
Berühren gefährlicher aktiver Teile
This European Standard was approved by CENELEC on 2002-02-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50274:2002 E
BS EN 50274:2002
EN 50274:2002
-2-
Foreword
This European Standard has been prepared by WG 3 of Technical Committee CENELEC TC 17D, Low-voltage
switchgear and controlgear assemblies. It is intended as a complementary document to EN 60439-1. EN 60439-1
does not address in detail the issue of protection of skilled and instructed persons from electric shock when they
are required to gain access into the assembly to manually operated devices. The intent of this standard is to
provide additional requirements for the protection of these persons against electric shock.
The text of the draft has been submitted to the formal vote and was approved by CENELEC as EN 50274 on
2002-02-01.
The following dates were fixed:
–
–
latest date by which the EN has to be implemented at
national level by publication of an identical national
standard or by endorsement
(dop)
2003-02-01
latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2005-02-01
Annexes designated "informative" are given for information only.
In this standard, annex A is informative.
-3-
BS EN 50274:2002
EN 50274:2002
Contents
Page
Introduction .........................................................................................................................................................4
1
Scope........................................................................................................................................................5
2
Normative references ...............................................................................................................................5
3
Definitions .................................................................................................................................................5
4
Requirements ...........................................................................................................................................7
4.1
General requirements...............................................................................................................................7
4.2
Positioning of operating devices...............................................................................................................7
4.3
Measures ..................................................................................................................................................7
4.4
Space of protection...................................................................................................................................7
4.5
Base area .................................................................................................................................................7
4.6
Access area ..............................................................................................................................................8
4.7
Equipment installed on movable parts .....................................................................................................8
5
Tests .........................................................................................................................................................8
5.1
Operating devices and access area .........................................................................................................8
5.2
Finger protected and back of the hand protected locations .....................................................................8
Annex A (informative) Figures for explanation .................................................................................................9
Figure 1 – Permissible area for locating of operating devices............................................................................9
Figure 2 – Maximum and minimum height of the base area depending on the service position .....................10
Figure 3 – Operating space for pushbutton actuation ......................................................................................11
Figure 4 – Operating space for actuation by rotary means ..............................................................................12
Figure 5 – Example for operating space during activation by pushbutton........................................................13
BS EN 50274:2002
EN 50274:2002
-4-
Introduction
Within the European Community there are a number of Directives which impact upon electrical equipment
including switchgear and controlgear assemblies with regard to the health and safety of the users and others
when at work. The Framework Directive (89/391/EEC) on Health and Safety sets out in article 6 - General
Obligations on Employers. These include a set of criteria to be observed. This listing is in a preferred order, and
in the case of switchgear and controlgear assemblies and their operation, the intent can be summarised as
follows.
a)
Remove the danger - in the case of assemblies where access inside for the operation of certain devices is
required, this can be achieved by either isolating the assembly before entry is permitted or ensuring that the
degree of protection of these devices and the accessible surrounding areas is not less than IPXXB
according to EN 60529. For assemblies located in areas set apart with access restricted to skilled and
instructed persons the assembly can be isolated before access is permitted or the operating device has a
degree of protection of not less than IPXXB according to EN 60529.
Or if this is not possible
b)
Separate the person from the danger by means of screens, barriers or obstacles.
This standard sets out requirements according to b) for assemblies where the measures for the protection
of persons as set out in a) above cannot be achieved.
Or if this is not possible
c)
Provide personal protective equipment to ensure the health and safety of the person – this is a measure of
last resort and is not considered suitable for these assemblies.
In addition, the requirements set out in both the Low Voltage Directive (73/23/EEC) and the use of Work
Equipment Directive (89/655/EEC) together with both of their Amending Directives (93/68/EEC and 95/63/EEC)
need to be observed. The particular article of the LVD to be considered is article 2 together with clauses 1 and 2
of annex 1.
Within the use of Work Equipment Directive, article 3 is particularly relevant to the design and construction of
switchgear and controlgear assemblies. Controls of any description should be sited in locations such that when
they are actuated, the operator is not exposed to any danger nor risks to health.
The preferred approach is to ensure that the assembly has a degree of protection not less than IPXXB at the
operating faces. Alternatively, the assembly should be designed and constructed so that the controls are set
apart in a safe location within the assembly where there are no hazardous live parts. It should be noted that the
Basic Safety Publication (EN 61140) sets a minimum level of protection against electric shock of IPXXB for
equipment.
-5-
1
BS EN 50274:2002
EN 50274:2002
Scope
This standard applies to low-voltage switchgear and controlgear assemblies with a rated voltage not exceeding
AC 1 000 V or DC 1 500 V. It sets out the requirements for the provision of additional features to provide
protection against electric shock from direct contact with hazardous live parts only for skilled and instructed
persons when they are required to manually actuate devices within the assembly and where a level of protection
for the operating face of not less than IPXXB cannot be achieved. These devices are those only accessible via a
door or cover requiring a key or tool to open it or in an assembly located in an area set apart and where the
access to that area is restricted solely to skilled or instructed persons.
This standard does not apply to
–
manually operated devices and their locations where access is available to ordinary persons,
–
low-voltage switchgear and controlgear assemblies where the operating voltage does not exceed AC 50 V
or DC 120 V and there is protective separation, in accordance with EN 61140, between these circuits and
any other circuits,
NOTE Voltages generated by means of auto-transformers, potentiometers, semiconductor components etc. do NOT
meet these requirements.
–
low-voltage switchgear and controlgear assemblies where protection of persons is provided by limitation of
steady-state touch current or charge in accordance with EN 61140.
2
Normative references
This European Standard incorporates, by dated or undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed hereafter. For
dated references, subsequent amendments to or revisions of any of these publications apply to this European
Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of
the publication referred to applies (including amendments).
EN 60529, Degrees of protection provided by enclosures (IP Code) (IEC 60529)
EN 61032, Protection of persons and equipment by enclosures – Probes for verification (IEC 61032)
EN 61140, Protection against electric shock – Common aspects for installation and equipment (IEC 61140)
IEC 60050-195, International Electrotechnical Vocabulary – Part 195: Earthing and protection against electric
shock
IEC 60050-826, International Electrotechnical Vocabulary – Part 826: Electrical installations of buildings
3
Definitions
For the purposes of this European Standard, the following terms and definitions apply.
3.1
low-voltage switchgear and controlgear assembly (ASSEMBLY)
a combination of one or more low-voltage switching devices together with associated control, measuring,
signalling, protective, regulating equipment, etc., completely assembled under the responsibility of the
manufacturer with all internal electrical and mechanical interconnections and structural parts
3.2
hazardous live part
live part which, under certain conditions, can give a harmful electric shock [IEV 195-06-05]
3.3
operating device
actuator (e.g. pushbutton, toggle) and replaceable warning or protective device (e.g. screw plug fuse, flashing
light) which serves to operate, protect or indicate the operating status of an equipment or installation
BS EN 50274:2002
EN 50274:2002
-6-
3.4
protection against unintentional direct contact
protection of skilled and/or instructed persons against unintentional direct contact of hazardous live parts
NOTE Hazardous live parts are protected so as to prevent unintentional direct contact with fingers, hands, arms or other
parts of the body of an operator while actuating operating devices.
3.5
space of protection
space designated in an assembly where skilled and/or instructed persons can activate the operating devices
without danger; defined by the base area around the operating device and by the access area in front of the
operator
NOTE Space of protection is shown in Figure 2.
3.6
base area
area limiting the operating space at the side of the operating device
NOTE Base area is shown in Figure 3.
3.7
access area
area limiting the operating space at the operator's side
NOTE Access area is shown in Figures 3, 4 and 5.
3.8
finger protection
protection against access to hazardous live parts with a finger
3.9
back of the hand protection
protection against access to hazardous live parts with the back of a hand
3.10
obstacle
a part preventing unintentional direct contact, but not preventing direct contact by deliberate action
[IEV 826-03-14]
3.11
mounting height
distance between the standing area of the operator and the mid point of the actuation
3.12
operating outline
envelope defined by all positions of motion and rest of the operating device
3.13
(electrically) skilled person
person with relevant education and experience to enable him or her to perceive risks and to avoid hazards
which electricity can create [IEV 195-04-01]
3.14
(electrically) instructed person
person adequately advised or supervised by electrically skilled persons to enable him or her to perceive risks
and to avoid hazards which electricity can create [IEV 195-04-02]
-7-
4
4.1
BS EN 50274:2002
EN 50274:2002
Requirements
General requirements
The operating devices shall be designed and positioned in such a way that they can be reached and actuated
without unintentional direct contact of hazardous live parts.
4.2
Positioning of operating devices
The positioning of operating devices shall allow activation in a standing or kneeling position.
The permissible area for locating of operating devices is shown in Figure 1.
The permissible area for locating can be extended in exceptional cases, if a suitable safe standing area can be
provided.
Subject to agreement between the manufacturer and user, alternative arrangements for the location of operating
devices can be specified provided there is a suitable safe standing area.
4.3
Measures
The required protection shall be ensured by one of the following measures, or their combination as appropriate:
–
functional design of the equipment to be mounted in the operating space;
–
distances between operating devices and hazardous live parts;
–
obstacles protected against unintentional displacement or removal.
Precautions against intentional contact are not required.
4.4
Space of protection
Hazardous live parts located at least partially in the operating space shall have a degree of protection of not less
than IPXXA (back of the hand protected), but see 4.5.
The position and the dimensions of the operating space depend on the geometrical characteristics, location and
type of the operating devices as well as the service position of the operator ("standing" or "kneeling", see
Figure 2).
The allocation of the base area (see Figures 3 and 4) to an operating device, depends on the type of activation
and the size of the operating device.
The access area depends on the service position of the operator (see Figure 2). The nominal distance between
the base area and the access area is taken as 500 mm.
The minimum/maximum height of the base area shall be as follows (see Figure 2):
kneeling position:
200 mm / 1 200 mm
standing position:
800 mm / 1 800 mm and
above 1 800 mm up to 2 000 mm with reduced mounting depth
In case of access to operating devices being located on the side wall of the assembly, the operating space is
limited to 300 mm x 300 mm (see Figure 5). Other restrictions of the operating space shall meet the
requirements of 4.5 and 4.6.
4.5
Base area
The base area shall have a back of the hand protection and shall have a part with finger protection in the
immediate vicinity of the operating device (see Figures 3, 4 and 5).
BS EN 50274:2002
EN 50274:2002
-8-
The finger protected part of the base area extends in the depth up to 80 mm.
The hand protected part of the base area extends up to 25 mm behind the base area.
The geometrical form of a base area depends on the kind of operation and of the geometrical characteristics of
the actuator
–
when actuated by pushbutton the base area comprises an area of 100 mm from the outside rim of
the actuator and the finger protected area of the base area comprises an area of 30 mm from the
outside rim of this actuator (see Figure 3),
–
when actuated by other means (e.g. toggle, rotary or swivel) the base area depends on the operating
outline. The base area boundary ends at a distance of 100 mm and the finger protected area with a
distance of 30 mm from the operating outline (see Figure 4).
4.6
Access area
The access area is a rectangle of 400 mm width and a height of
–
700 mm for operator working in a standing position,
–
500 mm for operator working in a kneeling position (see Figures 3 and 4).
The access area lower edge is located at a height of
–
1 100 mm for operator working in a standing position,
–
600 mm for operator working in a kneeling position
above the standing area level (see Figure 2).
4.7
Equipment installed on movable parts
When electrical equipment is located on movable parts, e.g. doors, covers, lids, their hazardous live parts (e.g.
at measuring instruments, indicator boards, control switches, clamps) shall be at least finger protected by
design, location or by protective provisions.
5
Tests
The following verifications shall be carried out:
5.1
Operating devices and access area
Compliance with the requirements of clause 4 shall be verified by visual inspection and/or measurement and/or
test.
5.2
Finger protected and back of the hand protected locations
Finger protection and back of the hand protection shall be verified in accordance with EN 60529. Finger
protection shall be verified by use of test probe 11 (unjointed test finger) in accordance with EN 61032.
BS EN 50274:2002
EN 50274:2002
-9-
Annex A
(informative)
Figures for explanation
Dimensions in mm
200
1
2
1800
2000
3
200
4
300
500
Key:
1
2
2, 3
4
Front of the assembly
Permissible area for locating of operating devices at the side
Permissible area for locating of operating devices at the back
Standing area of the operator
Figure 1 – Permissible area for locating of operating devices
1
max.
2000
1800
- 10 -
max.
1800
max.
1200
1100
1100
min.
800
600
min.
200
2
Key:
1
2
BS EN 50274:2002
EN 50274:2002
Dimensions in mm
Front of the assembly
Standing area of the operator
Figure 2 – Maximum and minimum height of the base area depending on the service position
BS EN 50274:2002
EN 50274:2002
- 11 -
Dimensions in mm
4
400
4
3
2
8
1
80
10
25
5
500
6
Key:
1
2
3
4
5
6
7
8
9
10
7
Base area
Mounting plate
No additional requirement
Area with back of the hand protection
Area with finger protection
Switch socket
Pushbutton
Access area
Front of the assembly
500 mm for kneeling position / 700 mm for standing position
Figure 3 – Operating space for pushbutton actuation
9
BS EN 50274:2002
EN 50274:2002
- 12 -
Dimensions in mm
5
4
400
1
2
4
3
8
80
10
30
5
6
30
100
Key:
1
2
3
4
5
6
7
8
9
10
30
100
25
500
7
Base area
Mounting plate
No additional requirement
Area with back of the hand protection
Area with finger protection
Switch socket
Toggle
Access area
Front of the assembly
500 mm for kneeling position / 700 mm for standing position
Figure 4 – Operating space for actuation by rotary means
9
BS EN 50274:2002
EN 50274:2002
- 13 -
Dimensions in mm
2
300
1
3
4
5
max.
300
6
9
7
400
Key:
1
2
3
4
5
6
7
8
9
8
Base area
Mounting plate
No additional requirement
Area with back of the hand protection
Area with finger protection
Switch socket
Pushbutton
Access area
Front of the assembly
The operating device is installed at the side wall (top view) or activation by pushbutton located at the side.
Figure 5 – Example for operating space during activation by pushbutton
BS EN
50274:2002
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