DSH 261 Requiremwents for parts providing earth continuity

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DSH 261 4 P( k5 f4 h8 L: ~8 X& T

Requiremwents for parts providing earth continuity # N2 W6 `% g: t$ b2 _- x  m

27, 28.3, 28.4

60335-1(ed.3) $ K7 L, P( L9 W: D8 \8 B

Standard: IEC60335-1, Ed. 3 Sub clauses: 27, 28.3, 28.4
Sheet n. 261
, R0 D6 @' |9 F1 n* q# A: X+ f: {: V3 mSubject: Requirements for parts providing earth continuity
, R2 v' L8 x- W2 a9 v* a% B* }, nKey words:
4 G/ j3 h7 N" v( e$ d- resistance to corrosion
- space threaded screw
8 a3 F9 d# f) mDecision n. 17 taken at 35th meeting/1998
6 p% r5 s/ {. e) P  ]! aQuestions:
1. Clause 27.4 requires that parts providing earth continuity shall have adequate resistance
1 }4 D! K  u1 m$ K  fto corrosion. In particular, steel parts are required to have at least 5μm electroplating
On what basis are laboratories stating compliance for this requirement?
2. 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
of clauses 28.3 and 28.4, with the example of figure below ?
Decisions:
3 j% F8 [( d! n6 ?! p1 V1 – 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
of compliance is also accepted.
2- The construction presented is not acceptable. The use of space threaded screws is only
acceptable if two space-threaded screw are used (§28.3). In this case, no spring washer is
# M' L) R2 H5 _. lrequired (§28.4). The use of only one space-threaded screw with spring washer is not in
accordance with the standard.
8 M& N' E# w6 ]: `! D" Y

1 x4 `, D2 }1 L* n1 }& O& E4 W3 L# j