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LZ说的要求其实在标准当中是来源于7.2.1的这段话:
6 |$ u1 r5 O& E/ m- k% [$ @; [Metal parts of luminaires which may become live in the event of an insulation fault and which) A6 K% ?4 F( i0 k( {
are not accessible when the luminaire has been mounted, but are liable to come into contact
6 i0 O4 V% z3 E6 [$ q5 Twith the supporting surface, shall be permanently and reliably connected to an earthing; [' V4 K7 j) `7 [
terminal.
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所以问题的关键在于以下两点:$ z& D- S$ Q, S% B9 k. s! F0 T
1、灯具内部的基本绝缘部件会不会与金属支架接触。如果是不可能接触到灯具内部的基本绝缘件,那么其实支架无需接地;) k' D; q; L8 [
8 @; t+ E z' G2、如果考虑了上述第一点判断支架需要接地,那么是否可以认为安装螺钉+菊花垫片提供了可靠的接地呢?我的理解是要考虑三方面:4 p3 }! v+ }# H2 P) D* S
2.1 接地电阻测试; / m, |; N/ r) g/ ]8 X
2.2 满足4.11.3的要求(这里有菊花垫片,可以认为满足了4.11.3的要求); ! m/ ]/ V a$ H% L
2.3 在7.2.1要求‘permanently’永久地连接到接地端子(那么很多机构会认为固定支架的螺钉在安装过程中需要拆装,一次不是一个永久的接地连接。其实这也是合理的,因为你无法保证灯具经过安装后,支架和灯外壳之间还能保持良好的接地连接)
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至于楼上提及的金属外壳是喷漆或者电镀的其实不是关键,标准当中另有条款规定了:
4 ~8 l2 d- d( b/ |) k% Y' T7.2.8 Either the screw or the other part of the earth terminal shall be made of brass or other; J8 Y; [2 B( g2 G: R
non-rusting metal or a material with a non-rusting surface and the contact surfaces shall be
) s- n& c. x7 u# wbare metal.: N" @1 A$ }, Y5 i0 o* {" C7 Y
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