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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 _/ G& ~3 Y/ g' ~7 BMetal parts of luminaires which may become live in the event of an insulation fault and which% [6 U/ r1 o: ~. Z. L
are not accessible when the luminaire has been mounted, but are liable to come into contact
% H/ C6 r) _ h0 C: V I: X9 T& Gwith the supporting surface, shall be permanently and reliably connected to an earthing
( S# [( d% J- l, h! w$ ]( [1 mterminal.
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* v1 \% N1 A' z" i) Q所以问题的关键在于以下两点:
" |; @8 F; Q) l1、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;
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2、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:
- Y4 q$ N, ?4 w- A 2.1 接地电阻测试;
- m( N0 v, p' e$ | 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);
% T$ i) ^& ~/ q; z' |! B' R 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)% T# V- D+ |; h' u+ c4 h' d
% w) O+ B. Z6 [& g) \. @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:5 ~9 A, q0 k% I- F: T6 `
7.2.8 Either the screw or the other part of the earth terminal shall be made of brass or other
2 h- A i. Y* e- r2 C9 fnon-rusting metal or a material with a non-rusting surface and the contact surfaces shall be: s! ^$ W! s% ?; {$ l5 M
bare metal.
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