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|  DSH 261
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| Requiremwents for parts providing earth continuity% ~& x% r+ t% G+ n \$ r ?
| 27, 28.3, 28.4
: T0 j; H$ j7 X- r: T | 60335-1(ed.3)
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Standard: IEC60335-1, Ed. 3 Sub clauses: 27, 28.3, 28.4
& Z- G' C9 ~. o7 H% k1 h& Z t. JSheet n. 261
# t, d2 z1 G+ \, [: c; nSubject: Requirements for parts providing earth continuity
! X9 @: ?' x) m& \6 X0 e4 ZKey words:- h3 l3 ]+ }2 ~& Z
- resistance to corrosion2 J2 K m' h' m) a% L
- space threaded screw; N9 ]- G: B8 h" u6 i
Decision n. 17 taken at 35th meeting/1998
, U! h1 a7 a7 f% c0 E E' I' w9 nQuestions:
+ r2 ]8 h& T! j# a3 D8 h1. Clause 27.4 requires that parts providing earth continuity shall have adequate resistance
" O M8 ?- |) X) ~: F( Nto corrosion. In particular, steel parts are required to have at least 5μm electroplating
, v5 B7 v: U# G& m/ TOn what basis are laboratories stating compliance for this requirement?; ~# V4 F' N' i4 G/ {: {
2. In the instance where a space threaded screw is used to provide earthing provision for a
2 l3 p5 e/ a4 l2 Zmotor frame (for instance), is the use of a space threaded screw without the use of a spring
0 r( ]$ m8 b) u2 g, P9 b- P1 Awasher a satisfactory earthing method for unpainted surfaces, considering the requirements
% i5 K9 `& c6 ]8 @of clauses 28.3 and 28.4, with the example of figure below ?) A* L3 P& p0 d6 y& N0 ]
Decisions:: n7 W. v. e" n6 b3 p! S/ G$ |7 k
1 – The adequate thickness of electroplated coating for steel part providing earth continuity
/ r+ x$ o6 {2 B$ ]& `is checked as indicated in note 4, using ISO2178 or ISO1463. The manufacturer declaration* @* b0 L/ y1 v/ d, }8 `
of compliance is also accepted.
, j' ~+ A0 m) O$ T- C2- The construction presented is not acceptable. The use of space threaded screws is only- L+ V+ {9 N. o+ @
acceptable if two space-threaded screw are used (§28.3). In this case, no spring washer is# j4 S) n% _6 H* f2 @' h
required (§28.4). The use of only one space-threaded screw with spring washer is not in
7 Q2 p% p6 { {7 L0 ^2 ~( p# Kaccordance with the standard.2 q( m% U; J# Q; z9 y
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