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| DSH 394A
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| Touch current for equipment having multiple supplies supplying power simultaneously
Z+ p9 g7 F% j0 L. n7 w | 5.1.2, last paragraph / 5.10 j: D- Z* F! q9 J5 S
| 60950-1(ed.1) & 60950(ed.3)
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, Y, I: m! h( N) f pStandard(s):, ?& L5 X- w8 Q4 ~- B
IEC 60950 (1999) 3rd Ed.1 Y% f" V L: Y$ |) k/ \! @
IEC 60950-1 (2001) 1st ed.: c H+ v8 Q# X$ w2 E7 n- w
Sub clause(s):
, F0 S: D; ?5 d5 h5.1.2, last paragraph p1 V& M; [+ Z
5.1
1 A0 g" l1 y: E% d0 k9 B6 K0 o. @! Q4 fSheet n°: 394A5 O7 N0 m/ p" Z. [3 n( {
Subject:
: p5 B E. e6 D: n, t+ {( CTOUCH CURRENT for equipment
* n/ i" y* ?/ B, Phaving multiple supplies supplying' ?% ~1 A. ?. H3 }2 L2 n+ Z
power simultaneously( ]! `- R5 p `
Key words:
- H! S" r3 e' S# F; V- TOUCH CURRENT for equipment
; y9 s1 B# p+ }5 k/ x* |4 g) i& Twith multiple supplies
! T0 v, c5 `7 y( O9 s% R" L1 P* xDecision taken at the 41st
% _. z3 Q ? ~ Z9 [( K! `0 M3 qCTL meeting 2004. This: U, k7 m- c& e1 p+ a) l- S
decision replaces n. 394 v; h, N8 @* U4 R+ J
taken at the 39th CTL l/ T! V9 X( Z4 e1 s Y, ?
meeting 2002! B' O' L6 a, F u. H
Question:
' c) n y2 W6 I$ ^1. Should the TOUCH CURRENT be measured for each individual supply source to determine if the
]# d2 d; v% r" J) aPROTECTIVE CONDUCTOR CURRENT exceeds 3.5 mA and if it does exceed, then require PERMANENT
$ x" h5 F7 P& G9 Hor PLUGGABLE TYPE B connection to the supply and meet 5.1.7?2 P9 `5 U$ s6 _. I& U3 a9 }
2. Should the cumulative TOUCH CURRENT be measured to determine if the total TOUCH CURRENT! ~- r$ F; z9 W7 S
exceeds 3.5 mA? If the total TOUCH CURRENT does exceed 3.5 mA then require that AC MAINS
$ {4 G: i/ n4 T( jSUPPLY to be connected to separate AC MAINS SUPPLY circuits with at least one source having a. G% F# U; u G- |0 T' s
reliable connection to PROTECTIVE EARTH (e.g. be PLUGGABLE TYPE B or PERMANENTLY4 f7 S2 L. M$ w; G
connected EUT?
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PLUGGABLE EQUIPMENT TYPE A does not have a reliable connection to building PROTECTIVE EARTH. Therefore, if
/ ?% f+ I: F4 u5 Cthe TOUCH CURRENT measurement exceeds 3.5 mA, then that particular source needs to be PERMANENTLY
/ ?0 t# I1 P9 i4 s' z1 _% E. K, U' Wconnected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. In older buildings, EARTH may2 ^) y5 s+ N$ o/ g5 ?* j/ W
not be present on the PLUGGABLE TYPE A socket outlets on the wall. The multiple connection does not help, as all: j; T) }$ q+ F
such socket outlets may not have EARTH connection. Therefore, if the individual or cumulative PROTECTIVE' l% R) u2 L9 ~" L
CONDUCTOR CURRENT exceeds 3.5 mA, then at least one of the sources needs to be PERMANENTLY connected or
6 L- A1 V/ w* U; u$ t2 whave a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. If one of the sources is required to be0 X2 K- N2 N, F) o+ m
PERMANENTLY connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH in order to1 _2 j; `! t# M3 @
comply with the TOUCH CURRENT requirements, the equipment shall be provided with both a marking on the equipment
6 O0 O3 y1 L( s( Z+ M1 \* p3 ]! Tand a statement in the installation instructions, specifying that the USER is to disconnect all power sources connection
+ a1 K8 ^$ E. f2 }+ Qbefore disconnecting the PERMANENT connection or the PLUGGABLE TYPE B connection
9 d. ?5 o5 `2 |0 [Decision:
$ Z$ u& j7 \- N/ U1 _: vSee copy of the CDV for IEC 60950-1 2nd edition on Page 2
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