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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:
. f" u1 R1 Z9 y% e+ M7 dMetal parts of luminaires which may become live in the event of an insulation fault and which
9 b7 @+ O6 a6 M: Ware not accessible when the luminaire has been mounted, but are liable to come into contact) j0 ?6 w: n$ r+ K7 T! s
with the supporting surface, shall be permanently and reliably connected to an earthing9 }( S/ Y: f+ q) d7 Z
terminal.
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! a( h, ^$ c$ O( b, Z$ |6 h6 }所以问题的关键在于以下两点:% q( ?2 g& j; N6 z e1 q, x2 v' A
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;) Q6 Q5 E+ r: n t# U( _
& H6 K$ C3 d: h( p9 z/ u2、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:3 f4 k, K6 K9 k* c' ~
2.1 接地电阻测试;
/ Y4 p- W! s5 X' E- 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); % U! y$ h! z9 V% e( l, f
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:
0 J8 N9 j1 o9 o5 P7.2.8 Either the screw or the other part of the earth terminal shall be made of brass or other
; V. I* y2 _+ R& \non-rusting metal or a material with a non-rusting surface and the contact surfaces shall be8 I- \7 U) c$ ^! v6 J- d
bare metal.( D* O& C8 D# z7 P! B# c6 p' n/ B
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