11.6.3.1 Independently mounted controls other than those declared for panel mounting shall either:
– fit a standard box as declared;
– be supplied with a conduit box if a special conduit box is required; or – be suitable for surface mounting on a plane surface.
11.6.3.2 If a special conduit box is required, it shall be delivered together with the control and the box shall be provided with the entries for conduit specified in IEC 60423.
11.6.3.3 Independently mounted controls for surface mounting used with buried installation (concealed wiring) not using an outlet box shall be provided with suitable holes on the back of the control allowing easy installation and connection to the terminals.
11.6.3.4 Independently mounted controls for surface mounting used with exposed wiring shall be provided with cable or conduit entries, knock-outs, or glands, which allow connection of the appropriate type of cable or conduit complying with the relevant IEC standard.
11.6.3.5 Independently mounted controls for surface mounting or the sub-bases for such controls shall be constructed in such a manner that the terminals for external conductors are accessible and can be used when the control or the sub-base is correctly fixed to its support and its cover (or the control) is removed.
11.6.3.6 Controls intended for mounting on an outlet box or similar enclosure shall have wiring terminals, other live parts and sharp-edged metal parts, earthed or not, located or protected so that they will not be forced against wiring in the box or enclosure during installation of the control.
11.6.3.7 Where back wiring terminals are used, they shall be recessed or be protected by close-fitting barriers or insulating materials or the equivalent that will prevent contact with wiring installed in the box.
Compliance with 11.6.3.1 to 11.6.3.7, inclusive, is checked by inspection.
Terminals that do not project into the box beyond the plane of the front edge of the box are acceptable.
Guards provided alongside terminals and extending at least 6,5 mm beyond the terminals before wiring, with a corresponding guard between double pole mechanism, are acceptable.
Attachment of cords 11.7
Flexing 11.7.1
11.7.1.1 The flexible cords of in-line cord and free-standing controls shall be capable of withstanding the flexing likely to occur in normal use. If a cord-guard is provided to meet this requirement it shall not be integral with the flexible cord if type X attachment is used.
11.7.1.2 Compliance is checked by subjecting the control, fitted with the flexible cord or range of flexible cords for which it is designed, to the following test.
11.7.1.2.1 The control is mounted in the flexing apparatus shown in Figure 9. The axis of oscillation is so chosen that the weight attached to the cord and the cord itself make the minimum lateral movement during the test.
Samples with flat cords are mounted so that the major axis of the cross-section is parallel to the axis of oscillation. Each flexible cord passing through the inlet opening is loaded with a weight of 1 kg. A current equal to the current passing through that particular core when the control is operated at rated voltage is passed through each core, the voltage between cores being maximum rated voltage. The oscillating member is moved backwards and forwards through an angle of 90° (45° on either side of the vertical). The number of flexings (that is one movement through 90°) being 5 000, and the rate of the flexing being 60 flexings per minute.
11.7.1.2.2 After the test, the sample shall show no damage within the meaning of this standard. During the test, no interruption of the current and no short circuit between the individual conductors shall occur, neither shall broken strands pierce the insulation to the outer surface of the accessory. A short circuit between individual conductors is considered to occur if the current reaches twice the value of the test current.
11.7.1.2.3 Not more than 10 % of the total number of conductors of the flexible cord shall have been broken.
Cord anchorages 11.7.2
11.7.2.1 Controls other than those integrated and incorporated, intended to be connected by means of a non-detachable cord, shall have cord anchorages such that the conductors are relieved from strain, including twisting, where they are connected to the terminals, and that their covering is protected from abrasion. It shall be clear how the relief from strain and the prevention of twisting is intended to be effected.
11.7.2.2 Cord anchorages of class II controls shall be of insulating material or, if of metal, be insulated from accessible metal parts or metal foil over accessible non-metallic surfaces by insulation complying with the requirements for supplementary insulation.
11.7.2.3 Cord anchorages of controls other than those of class II shall be of insulating material or be provided with an insulating lining, if otherwise an insulation fault on the cord could make accessible metal parts live. This lining, if any, shall be fixed to the cord anchorage, unless it is a bushing which forms part of a cord guard provided to meet the requirements of 11.7.1.
11.7.2.4 Cord anchorages shall be so designed that:
– the cord cannot touch clamping screws of the cord anchorage, if these screws are accessible metal parts;
– the cord is not clamped by a metal screw which bears directly on the cord;
– for type X attachment or type M attachment, at least one part is securely fixed to the control;
– for type X attachment or type M attachment, replacement of the flexible cord does not require the use of a special purpose tool;
– for type X attachment, they are suitable for the different types of flexible cord which may be connected;
– for type X attachment, the design and location make replacement of the flexible cord easily possible.
11.7.2.5 For other than type Z attachment, makeshift methods such as tying the cord into a knot, or tying the ends with string, shall not be used.
11.7.2.6 Glands shall not be used as cord anchorages in in-line cord controls using type X attachment unless they make provision for clamping all types and sizes of cords used in 10.1.4.
11.7.2.7 Screws, if any, which have to be operated when replacing the cord, shall not serve to fix any other component, unless either the control is rendered inoperable or manifestly incomplete if they are omitted or incorrectly replaced, or the component intended to be fixed cannot be removed without the aid of a tool when replacing the flexible cord.
11.7.2.8 Compliance with 11.7.2.1 to 11.7.2.7, inclusive, is checked by inspection and by the tests of 11.7.2.9 to 11.7.2.15 inclusive. Integrated and incorporated controls, intended for the connection of flexible cords, are tested according to the relevant standard for the equipment in which they are integrated or incorporated.
11.7.2.9 The control is fitted with a flexible cord and the conductors are introduced into the terminals, the terminal screws, if any, being tightened just sufficiently to prevent the conductors from easily changing their position. The cord anchorage is used in the intended manner, the screws being tightened with a torque equal to two-thirds of the torque specified in 19.1.
11.7.2.10 After this preparation, it shall not be possible to push the cord into the control to such an extent that the cord or internal parts of the control could be damaged, or that internal parts are interfered with in a way which might impair compliance with this standard.
11.7.2.11 The cord is then subjected to pulls of the value and number shown in Table 9. The pulls are applied in the most unfavourable direction, without jerks, each time for 1 s.
11.7.2.12 Immediately afterwards, the cord is subjected for 1 min to a torque of the value shown in Table 9.
Table 9 (11.7.2 of edition 3) – Pull and torque values
Control Pull a
N Torque a
Nm Number of pulls a Free-standing controls and
independently mounted controls:
Up to and including 1 kg 30 0,1 25
Over 1 kg up to and including 4 kg 60 0,25 25
Over 4 kg 100 0,35 25
In-line cord controls (other than
free-standing controls) 90 0,25 100
a Some equipment standards may require a different value.
11.7.2.13 For type X attachment, the tests are made first with the lightest permissible type of flexible cord of the smallest cross-sectional area used in 10.1.4, and then with the next
heavier type of flexible cord of the largest cross-sectional area used. For type M attachment, type Y attachment or type Z attachment, only declared or fitted cord is used.
11.7.2.14 During the tests, the cord shall not be damaged. After the tests, the cord shall not have been displaced longitudinally by more than 2 mm, the conductors shall not have been moved over a distance of more than 1 mm in the terminals, and there shall be no appreciable strain at the connection. Creepage distances and clearances shall not have been reduced below the value specified in Clause 20.
11.7.2.15 For the measurement of the longitudinal displacement, a mark is made on the cord while it is subjected to the pull, at a distance of approximately 20 mm from the cord anchorage, before starting the tests. After the tests, the displacement of the mark on the cord in relation to the cord anchorage is measured while the cord is subjected to the pull.
Size of cords – non-detachable 11.8
11.8.1 Non-detachable cords shall not be lighter than ordinary tough rubber sheathed flexible cord, designated EN 50525-2-21 , or ordinary polyvinyl chloride sheathed flexible cord, designated EN 50525-2-21 . The use of a lighter flexible cord is permissible if allowed in
SELV devices (sensors/units).
a particular equipment standard or for connection to external Compliance is checked by inspection.
11.8.2 Controls fitted with non-detachable cords shall have a cord with conductors of a size not less than that shown in Table 10.
Table 10 (11.8.2 of edition 3) – Minimum cord conductor sizes
Current in relevant circuit a
A Nominal cross-sectional area
mm2
Up to and including 6 c 0,75
over 6 up to and including 10 1
over 10 up to and including 16 1,5
over 16 up to and including 25 2,5
over 25 up to and including 32 4
over 32 up to and including 40 6
over 40 up to and including 63 10
a Requirements for applications greater than 63 A are under consideration.
b
c Lower values than 0,75 mm2 are permitted for class III controls or if permitted in a particular equipment or installation standard.
Compliance is checked by inspection.
11.8.3 The space for the flexible cord inside the control shall be adequate to allow the conductors to be easily introduced and connected, and the cover, if any, fitted without risk of damage to the conductors or their insulation. It shall be possible to check that the conductors are correctly connected and positioned before the cover is fitted.
Compliance is checked by inspection and by connecting cords of the largest cross-sectional area used in 10.1.4.
Inlet openings 11.9
11.9.1 Inlet openings for flexible external cords shall be so designed and shaped, or shall be provided with an inlet bushing, so that the covering of the cord can be introduced without risk of damage.
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11.9.1.1 Conduit entries and knock-outs of independently mounted controls shall be so designed or located that introduction of the conduit or conduit fitting does not affect the protection against electric shock or reduce creepage distances and clearances below the values specified in Clause 20.
Compliance is checked by inspection.
11.9.2 If an inlet bushing is not provided, then the inlet opening shall be of insulating material.
11.9.3 If an inlet bushing is provided, then it shall be of insulating material, and – shall be so shaped as to prevent damage to the cord,
– shall be reliably fixed,
– shall not be removable without the aid of a tool,
– shall, if type X attachment is used, not be integral with the cord.