Well… there are no rules that I am aware of that would prohibit such
construction. All accessible conductive parts should be double-insulated from
mains (Class II construction). Otherwise, the kettle is Class 0 construction
with a Class I mains cord and connector.
Rich
From: Scott Xe [mailto:scott...@gmail.com]
Sent: Tuesday, February 17, 2015 4:29 PM
To: ri...@ieee.org
Cc: EMC-PSTC@listserv.ieee.org
Subject: Re: Class 1 appliances
I have encountered some audio and video receivers with FE. It is classified as
class I as it is required by connecting to the earth. The product itself is
class II construction. The earth connecting wire inside the power supply is
not green/yellow colour. However the examples had no connection on the earth
pin of kettle main connector - no FE and FE at all.
On Wednesday, 18 February 2015, Richard Nute <ri...@ieee.org
<mailto:ri...@ieee.org> > wrote:
Hi Scott:
>From the outside, any product with a three-wire
(with a PE conductor) is deemed Class I.
Inside, most products will have both Class I and
Class II construction.
Accessible conductive parts must either be
"bonded" to the equipment PE terminal or provided
with a second insulation, either of which provides
protection against electric shock in the event of
failure of basic insulation. If an accessible
conductive part is not connected to earth, then it
should be double-insulated from the mains. In
many cases, air (reinforced clearance) separates
the accessible conductive part from the mains; the
part is a long way from the mains.
Today, many equipments with a PE mains supply cord
do not employ Class I construction. The PE
terminal inside the equipment is used only for
connection of a functional earth, FE, to earth.
An example is connection of Y1 (EMI suppression)
capacitors to earth.
Regardless of construction, any equipment with a
PE is Class I. Any equipment with a two-wire
mains cord is Class II (or Class 0, which, as John
has mentioned, is outlawed in most countries).
Some accessible conductive parts are connected to
earth via a FE rather than bonded to the PE
terminal. (An example is the output d.c. of a
"brick" type power supply as is used with a laptop
computer.) This is okay as long as the FE is
double-safeguarded from the mains. But, in the
field, the earthing cannot be discriminated
whether it is FE earthed or is PE earthed. If the
PE test is applied to the FE, the FE is likely to
fail. Such a test result will fail equipment
safety testing as well as destroy the equipment.
Enjoy!
Rich
-----Original Message-----
From: Scott Xe [mailto:scott...@gmail.com <javascript:;> ]
Sent: Tuesday, February 17, 2015 8:42 AM
To: EMC-PSTC@LISTSERV.IEEE.ORG <javascript:;>
Subject: [PSES] Class 1 appliances
I have seem a couple of appliances that classified
in its compliant report as class 1 appliance
without any connection to the earth pin of 3-pin
kettle male IEC connector. Under this
construction, the earth continuity measurement is
infinitive. What is main purpose for the 3-core
mains cord and not use 2-core cord straightway?
How come can such construction be considered as
class 1 appliance? is there any quick way to
identify the appliance class? Your advice is
appreciated!
Best regards,
Scott
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