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| DSH 394A
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& h4 Y. C. u& a | Touch current for equipment having multiple supplies supplying power simultaneously
4 z% x) U% v) i0 m+ C: D3 v | 5.1.2, last paragraph / 5.1
! \# a6 l, F" d J! \% p* S | 60950-1(ed.1) & 60950(ed.3)& Q' t) y; o: P" g' p
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Standard(s):0 ^' L0 i* O% n7 F! r8 ?/ @6 f
IEC 60950 (1999) 3rd Ed./ q5 a3 l8 p( h0 u @6 V3 u
IEC 60950-1 (2001) 1st ed.
O& o- N! v# o3 c7 ~4 H; ^9 S- JSub clause(s):
& m3 x3 e' w# l% L5.1.2, last paragraph) O6 b+ t f* b# b5 x; G/ b
5.1
7 g1 l ^9 f; _Sheet n°: 394A* Y8 v' N2 D6 O+ e
Subject:
3 i9 E6 k. O* H" NTOUCH CURRENT for equipment
7 h' B% b. g% _& e( c) `" m2 A$ Qhaving multiple supplies supplying& P- t# Z# x0 J4 R- ]9 G/ X i: {
power simultaneously' G' V4 [) t+ V: q* H% [
Key words:
( S3 u. Y2 o. D# f, J" ?- TOUCH CURRENT for equipment- m- k6 G+ ~2 E% i% Y3 n! h2 P+ a
with multiple supplies
- I, x8 W! N0 O$ }3 I0 n. d4 DDecision taken at the 41st
5 s9 F" Y4 R4 d; |CTL meeting 2004. This6 k0 D; M5 s1 v' e4 L% `& A, X) f$ v, p
decision replaces n. 394
& [/ j2 \9 L) c1 ctaken at the 39th CTL
% k( q: m0 J) S3 Vmeeting 2002
' K" x8 \1 i; ?9 G3 Z6 j- YQuestion:
& _4 x3 H' p) R: a, `8 {1. Should the TOUCH CURRENT be measured for each individual supply source to determine if the6 o4 ]( ~( B Z$ k
PROTECTIVE CONDUCTOR CURRENT exceeds 3.5 mA and if it does exceed, then require PERMANENT6 ~; J; G! m5 W' n \ p) s
or PLUGGABLE TYPE B connection to the supply and meet 5.1.7?, J6 m" ?+ b9 ]
2. Should the cumulative TOUCH CURRENT be measured to determine if the total TOUCH CURRENT
- A. X* d$ O1 o1 @5 |exceeds 3.5 mA? If the total TOUCH CURRENT does exceed 3.5 mA then require that AC MAINS
k8 D6 r7 g( b! H* w/ ~SUPPLY to be connected to separate AC MAINS SUPPLY circuits with at least one source having a/ Z* a$ u0 P3 ~% B% o, H3 o5 j0 a
reliable connection to PROTECTIVE EARTH (e.g. be PLUGGABLE TYPE B or PERMANENTLY; S8 }) j, C; p g) T1 h
connected EUT?$ ]& `5 D& [: {8 z/ N
Rationale:8 I7 @6 h) O+ l4 N3 X
PLUGGABLE EQUIPMENT TYPE A does not have a reliable connection to building PROTECTIVE EARTH. Therefore, if, d7 Z, V! _. \# Z4 [
the TOUCH CURRENT measurement exceeds 3.5 mA, then that particular source needs to be PERMANENTLY7 ?/ A! i- {# m1 _- `, J
connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. In older buildings, EARTH may
: f( J" G: v% a* {& p& a: vnot be present on the PLUGGABLE TYPE A socket outlets on the wall. The multiple connection does not help, as all
$ T% n1 H0 I5 wsuch socket outlets may not have EARTH connection. Therefore, if the individual or cumulative PROTECTIVE
9 x9 P% t. \ }1 n# N' h# HCONDUCTOR CURRENT exceeds 3.5 mA, then at least one of the sources needs to be PERMANENTLY connected or
- [8 {7 A* q q9 G$ Whave a PLUGGABLE TYPE B connection to PROTECTIVE EARTH. If one of the sources is required to be
; J+ ~# e5 ~; Y8 p4 u* q& V1 fPERMANENTLY connected or have a PLUGGABLE TYPE B connection to PROTECTIVE EARTH in order to
9 q R7 J* @% r3 T6 r b& U6 L% i$ `comply with the TOUCH CURRENT requirements, the equipment shall be provided with both a marking on the equipment
, i/ C' \, k% b( f- Wand a statement in the installation instructions, specifying that the USER is to disconnect all power sources connection! x8 K0 `) B) q2 m6 k* A
before disconnecting the PERMANENT connection or the PLUGGABLE TYPE B connection% y( A. P% Z# g# S
Decision:. s+ b5 Y' R/ L: @4 I
See copy of the CDV for IEC 60950-1 2nd edition on Page 2
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