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It comes from UL 746C. ?: n$ M4 R% P) Q, F7 _
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55DV.4.1 In addition to the other requirements in this Standard, flammability, mechanical
/ P2 X- Y2 t" w: `2 X( Mabuse and mold stress tests shall be conducted. Polymeric ENCLOSURES and covers shall
( {( ]7 ~2 E' C5 b% x. v2 |5 Hcomply with the requirements for resistance to impact and drop as indicated below, and
8 {' ]. e6 V# `/ ]6 Y Bthe requirements for mold stress release distortion, in the Standard for Polymeric Materials: J" t$ N1 i; Q" M; j
- Use in Electrical Equipment Evaluations, UL 746C.8 d7 \" E( _$ N( ^) q, a$ P
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In UL 746C, the standards says
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- y% z) c. M1 X! w6 d! }6 X58.3 Each of three samples of the appliance shall be subjected to a single impact of the value shown in+ _% A1 _% s' W2 `7 y
Table 58.1 for the applicable equipment type, on any surface that can be exposed to a blow during
8 Y$ S: I2 N0 J4 o9 f% ]intended use. This impact is to be produced by dropping a steel sphere, 50.8 mm (2 inches) in diameter, _$ b2 S' S; w, M. {, q$ T
and weighing 0.535 kg (1 .I8 Ib) mass from the height necessary to produce the specified impact as shown7 [8 V+ B, ]# L/ g: r
in Figure 58.2. The steel sphere shall strike the surface in a location different from those in the other two
+ ]8 Z5 l' t3 A5 F+ _( |& ^3 C* simpacts. For surfaces other than the top on an enclosure, either the sample could be supported on the6 G- t w0 H |% G
side and subjected to the ball impact mentioned above, or the steel sphere is to be suspended by a cord
3 _6 |9 c, C# X1 @- `2 y# Gand swung as a pendulum, dropping through the vertical distance necessary to cause it to strike the
9 j. r9 P8 T6 f# o" L! ?. xsurface with the specified impact as shown in Figure 58.2. Three samples shall be employed for the tests
" A1 O5 n7 N- N7 U1 zin the equipment restrained mode. However, if the manufacturer so elects, fewer samples may be used
0 O) z& B0 R+ _5 ?. C- Pin accordance with Figure 58.1. The overall performance is acceptable upon completion of any one of the
! Q, J" N1 V5 i9 m! n i* bsequences represented in Figure 58.1. |
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