UL-60947-7-1:2011 pdf free download – Underwriters Laboratories Inc. Standard for Safety Low-voltage switchgear and controlgear – Part 7-1: Ancillary equipment – Terminal blocks for copper conductors.
NOTE Screw-type clamping units are not suitable for the connection of flexible conductors with tin soldered ends.
The clamping units shall be able to withstand the forces that can be applied through the connected conductors.
Compliance is checked by inspection and by the tests of 8.3.3.1, 8.3.3.2 and 8.3.3.3.
No contact pressure shall be transmitted through insulating materials other than ceramic, or other material with characteristics not less suitable, unless there is sufficient resiliency in the metallic parts to compensate for any possible shrinkage of the insulating material.
The corresponding test is under consideration.
7.1.1 DV.1 D2 Modification by adding the following to 7.1.1:
In the U.S. for clamping units rated only for factory wiring, only 8.3.3.1 is applicable. In Mexico, all of 7.1.1 applies.
7.1.1DV.2 D2 Modification by adding 7.1.1DV.2.1 — 7.1.1DV.2.2.3
7.1.1DV.2.1 Current-carrying parts and their connections
7.1.1DV.2.1.1 A current-carrying part intended for use with copper wire shall be of copper, a copper alloy, or other material suitable for the purpose.
7.1.1DV.2.2 Wiring terminals
7.1.1DV.2.2.1 A wire-binding screw or stud-and-nut type terminal for field wiring may be employed for conductors not larger than 5,3 mm2 (10 AWG), provided that the application of normal clamping action as intended will not impair the integrity of the joint. See Solid-Wire Tightening Test, 8.3.3.6DV.2.
7.1.1DV.2.2.2 A field wiring connector employing a wire-binding screw or stud-and-nut terminal shall be capable of accommodating a three-quarter loop.
7.1.1DV.2.2.3 To determine compliance with 7.1.1DV.2.2, the conditions in (a) and (b) shall be met or, for a solid conductor, the test described in 8.3.3.6DV.2 shall be conducted. A terminal for a stranded conductor shall meet conditions described in (a) and (b).
a) The threaded screw or stud shall not have more than 12,6 threads per centimeter and shall not be smaller than 4,2 mm diameter for wire larger than 2,1 mm2 (14 AWG) and not smaller than 3,5 mm diameter for 14 AWG and smaller wire. A wire-binding screw or stud-and-nut type terminal shall be provided with upturned lugs, a cupped washer, barriers, or other equivalent means to hold the wires in position even if the screw or nut becomes slightly loose.
b) The tapped terminal plate shall not have less than two full threads, and shall be of metal not less than 1,3 mm thick for a wire larger than 14 AWG and not less than 0,76 mm thick 14 AWG or smaller wire. Threads provided by extruding a hole before tapping shall be counted it the thickness of the unextruded metal is not less than the pitch of the thread.
7.1.3 Clearances and creepage distances
For terminal blocks for which the manufacturer has stated values of rated impulse withstand voltage Ump and rated insulation voltage U, minimum values of clearances and creepage distances are given in tables 13 and 15 of IEC 60947-1.
For terminal blocks for which the manufacturer has determined no value of rated impulse withstand voltage Uimp guidance for minimum values is given in annex A.
Electrical requirements are given in 7.2.2.
7.1 .3DV D2 Modification by adding the following:
The spacings on a terminal block shall be as specified in Table 7.1.3DV.1. Alternately, the creepage and clearance distances given in Tables 13 and 15 of the standards contained in Annex DVB, Table DVB.2, reference no. 9, may be used.
Note: For information regarding verification of clearances and creepage distances by measurement, see the standards contained in Annex DVB, Table DVB.2, reference no. 9, Annex G.