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|  DSH 394A9 ^* d' Z6 ?; v8 e" w6 X
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9 c- V& k- x& d; J | Touch current for equipment having multiple supplies supplying power simultaneously
/ q5 b6 l# B+ n0 |! i" b" E | 5.1.2, last paragraph / 5.14 ^0 d) V: b# x- ^. \
| 60950-1(ed.1) & 60950(ed.3)
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Standard(s):
G; e/ P; [6 y: zIEC 60950 (1999) 3rd Ed.% E G- r; a) e$ |
IEC 60950-1 (2001) 1st ed.
: p7 m0 S: w3 p# _* U9 z' bSub clause(s):& V( k" H. L, \% b5 U' H
5.1.2, last paragraph2 s4 e' q, a- R k
5.1
( t$ m r; A, L, V# D- a3 w. w- TSheet n°: 394A6 [# a }- Y8 m, X8 I: s6 T
Subject: f' v! ^8 X. [% H
TOUCH CURRENT for equipment" K5 s2 a2 y/ i5 k+ _1 e
having multiple supplies supplying
+ \4 a; }* F1 Z9 o9 |$ ?1 a4 I. \power simultaneously' ^. W. N4 X5 z J
Key words:0 A9 [9 {/ P7 s$ Z3 s
- TOUCH CURRENT for equipment0 @1 P( A; |8 j- O# N2 s6 h
with multiple supplies. d8 n5 N r( S! I: U
Decision taken at the 41st
: n4 a3 y. O( v6 S5 tCTL meeting 2004. This
; _' W0 A0 X. }5 p7 _decision replaces n. 3942 O8 A6 M! D+ z
taken at the 39th CTL5 v; Y a8 k8 y6 U! C. q: |0 _
meeting 2002# Y( o; S7 z9 Y3 P( c9 B
Question:
7 W) t# n+ K# P$ s1. Should the TOUCH CURRENT be measured for each individual supply source to determine if the7 ^5 ~; E4 t$ D/ a! v: t/ F
PROTECTIVE CONDUCTOR CURRENT exceeds 3.5 mA and if it does exceed, then require PERMANENT
9 B5 l. G. u+ X: ~# Z. @or PLUGGABLE TYPE B connection to the supply and meet 5.1.7?
4 _( Y* S. l% a% X3 f5 o2. Should the cumulative TOUCH CURRENT be measured to determine if the total TOUCH CURRENT3 g; B) O) U" ^- o2 C2 l# v0 {
exceeds 3.5 mA? If the total TOUCH CURRENT does exceed 3.5 mA then require that AC MAINS
$ ], ]9 O: ~+ T3 S$ i; }# BSUPPLY to be connected to separate AC MAINS SUPPLY circuits with at least one source having a& v& g0 V( c4 W# L3 ^* Z
reliable connection to PROTECTIVE EARTH (e.g. be PLUGGABLE TYPE B or PERMANENTLY: O2 J& Y: ~% `; t" v- `. M/ J
connected EUT?6 j& R) V0 L* [2 W
Rationale:% P/ |' ^6 a; W: p" T
PLUGGABLE EQUIPMENT TYPE A does not have a reliable connection to building PROTECTIVE EARTH. Therefore, if
% z3 R, A8 V. Q7 ~" @$ W$ dthe TOUCH CURRENT measurement exceeds 3.5 mA, then that particular source needs to be PERMANENTLY
0 ~8 N' R* c( u1 J: Z# Vconnected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. In older buildings, EARTH may2 }. ^4 X& J. Q
not be present on the PLUGGABLE TYPE A socket outlets on the wall. The multiple connection does not help, as all
h! K. i4 b% T e( H( hsuch socket outlets may not have EARTH connection. Therefore, if the individual or cumulative PROTECTIVE- b7 D1 L" H/ G, w6 A7 c) `
CONDUCTOR CURRENT exceeds 3.5 mA, then at least one of the sources needs to be PERMANENTLY connected or
( A% ^+ E) q% j' |+ Uhave a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. If one of the sources is required to be s) _5 p- a/ Y5 Q/ y! d9 W
PERMANENTLY connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH in order to
) d8 F( i& c( dcomply with the TOUCH CURRENT requirements, the equipment shall be provided with both a marking on the equipment
- E2 i$ F6 X+ ]. T# qand a statement in the installation instructions, specifying that the USER is to disconnect all power sources connection
& x, O( s/ k3 u- \' ibefore disconnecting the PERMANENT connection or the PLUGGABLE TYPE B connection. Z4 g4 B' V/ m2 g% w' }
Decision:) z# {* Y5 c3 G5 |8 y
See copy of the CDV for IEC 60950-1 2nd edition on Page 28 ~* @& f8 ]- w* O. e
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