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24 Electrical Spacings
8 J, [. ~8 B- D* M24.1 The spacing between uninsulated live parts of opposite polarity, and between uninsulated live parts7 ]4 ?* b1 ~; T: [8 q
and metal that is capable of being grounded shall not be less than 1/4 inch (6.4 mm) through air or 3/8
' g, d( {# N# v- b9 tinch (9.5 mm) over surface. The outer wrap of an open core and coil ballast is determined to be an
4 c* Y* G: @1 U) }" m, u9 U# ]7 cuninsulated live part with respect to this requirement.$ a4 t c$ p* z) B
Exception No. 1: The spacing requirements do not apply between uninsulated live parts of a wiring device,
; M, |. f# C6 u$ ]" N5 h! m1 Psuch as a lampholder or switch, and dead metal that is part of the wiring device and including mounting
- c* z8 @( T6 r/ G9 | ^screws, rivets, yoke, clamp, or similar components; or for a portable luminaire provided with a grounding
; H" J/ \+ o9 n& A2 O2 ?means between such live parts and that part of the dead metal surface of the portable luminaire on which
6 I) Y9 F( d9 ]: u hthe device is mounted in its intended manner. See Figure 24.1.6 p4 y) z3 f1 |$ H" s5 \3 m3 W
Exception No. 2: When an isolated dead metal part is interposed between or is in close proximity to:5 a/ Q+ l0 \& O- h2 k( L5 T6 b
a) Live parts of opposite polarity;6 V: ~8 d, O) T
b) A live part and an exposed dead metal part; or% Y) N1 W2 {3 V! K1 _" p6 {: U
c) A live part and a dead metal part that is able to be grounded, the spacing shall not be less- I+ H0 Z" g4 V! F4 o+ e/ _
than 3/64 inch (1.2 mm) between the isolated dead metal part and any one of the other parts- J$ S/ y+ K) |9 s( u5 B
previously mentioned, provided the total spacing between the isolated dead metal part and the y% n( J+ J. w& b) ?
two other parts is not less than 1/4 inch (6.4 mm) through air or 3/8 inch (9.5 mm) over surface.
- O7 |) f7 x2 QException No. 3: The spacing between uninsulated live parts of a Class 2 circuit and between such parts
& ?# H; a/ U1 _+ }" z9 {and dead metal that is grounded in service is not specified.6 c. L$ r* x' |1 P: J
% e e' `3 t. A m各位大侠,UL153这章的dead metal part,是不是可以直接理解为非金属部件?( R4 O* d) g4 d
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