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21.1.1 The spacings through air and over surface in an appliance shall not be less than 1/16 inch (1.6
7 B/ c `# h' B6 f4 p, B; I! A; imm) between uninsulated live parts of opposite polarity; and between a rigidly mounted uninsulated live
4 f4 K8 G/ s( A% L, xpart and a dead metal part that either is exposed for persons to contact or may be grounded.
! w- [: \ V+ D5 `7 ]Exception No. 1: If exact centering of the cold pin of a sheathed-type heating element is required to
; m; @- t. R( L* I9 w$ Fmaintain the 1/16 inch (1.6 mm) spacing, a spacing of 3/64 inch (1.2 mm) in one location is acceptable.
3 u! T* t7 W$ p7 F5 j U& P, C) BException No. 2: Spacings in an appliance that comply with 21.1.2 need not comply with 21.1.1.& s0 h5 S2 `, F. b5 a' ~. `
( U8 `. b/ ^! j* l2 [+ N4 C21.1.2 At closed-in points only, such as the screw-and-washer construction of an insulated terminal
. o: P. W9 A/ K; T8 k5 K1 imounted in metal, a spacing of 3/64 inch (1.2 mm) is acceptable. Within a thermostat, except at contacts,
7 n) Q2 _0 x# N) w: I$ i! }the spacings between uninsulated live parts on opposite sides of the contacts shall not be less than 1/32% h- V# z& I5 L3 h
inch (0.8 mm) through air and 3/64 inch (1.2 mm) over the surface of insulating material, and the
' L5 g' }' W$ y' E* I3 rconstruction shall be such that the spacings are maintained permanently.! ]& d0 H* ~7 q3 t, S, O( v
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a. 21.1.1 中例外1,发热管里面有发热丝然后通过焊接一段延长出去(COLD PIN), 一般是圆柱体,EXACT centering 即COLD Pin 圆柱体中心,发热管有两端,意味着有两个cold pin, 这两个cold pin 圆柱体中心距离要求1.6mm, 后面说在一个位置可以有1.2mm 距离,什么叫一个位置(in one location)? 指的是那儿距离可以使1.2mm?+ ?1 J5 p& m! ?
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b. 21.1.2, except at contacts, contacts这里是指温控器里面的触点吗?还是指温控器端子引脚? 视乎是端子引脚对吧? 也就是说端子引脚要有1.6mm 电气间隙和爬电距离。然后说温控器两端子引脚间电气连接暴露导体可以是0.8mm 间隙,1.2mm 爬电?对吗? 什么样的结构是认为maintained permanently?+ r1 w+ P$ O# J: @, Y% R/ \$ P1 }! n# x
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