DSH 261 Requiremwents for parts providing earth continuity

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DSH 261 7 O0 H, J0 n/ @; w ( X/ Q$ _4 H4 R! Z8 F8 L/ N

Requiremwents for parts providing earth continuity

27, 28.3, 28.4 $ U- N% Z8 g" V& ~& O! X" ?

60335-1(ed.3) $ c3 i* m& F) k2 _; |( D

Standard: IEC60335-1, Ed. 3 Sub clauses: 27, 28.3, 28.4
Sheet n. 261
* }5 R8 r4 Z. \( S+ m, ~6 H* T5 RSubject: Requirements for parts providing earth continuity
Key words:
3 O" S3 \7 @% D- resistance to corrosion
- space threaded screw
0 R8 A0 @3 l' X" e' \$ Q* c& R' EDecision n. 17 taken at 35th meeting/1998
Questions:
1. Clause 27.4 requires that parts providing earth continuity shall have adequate resistance
to corrosion. In particular, steel parts are required to have at least 5μm electroplating
1 K( a6 _% R' n) O/ MOn what basis are laboratories stating compliance for this requirement?
; g2 A1 ]) x4 z2. In the instance where a space threaded screw is used to provide earthing provision for a
motor frame (for instance), is the use of a space threaded screw without the use of a spring
washer a satisfactory earthing method for unpainted surfaces, considering the requirements
# Q  o2 y( m( c/ Y$ tof clauses 28.3 and 28.4, with the example of figure below ?
& b. l9 I$ O' c9 o7 Q$ {Decisions:
  q' [9 N9 F; z# @% m& L, d, W1 – The adequate thickness of electroplated coating for steel part providing earth continuity
is checked as indicated in note 4, using ISO2178 or ISO1463. The manufacturer declaration
+ r+ U8 O+ D4 z1 q+ J# ~4 iof compliance is also accepted.
2- The construction presented is not acceptable. The use of space threaded screws is only
5 H$ }  F5 {5 {% C. Cacceptable if two space-threaded screw are used (§28.3). In this case, no spring washer is
. s6 ]7 d5 d# P. j& E$ r$ \required (§28.4). The use of only one space-threaded screw with spring washer is not in
) _2 F- ?8 x# c, p8 haccordance with the standard.