4SW
E-Mail :john.cr...@scotland.ncr.com
Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243.
From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Gary McInturff
Sent: 14 November 2003 18:46
To: Crabb, John; Ned Devine; IEEE EMC/Product Safety
2.6.1 of IEC 60950-1 refers to parts of equipment shall be reliably
connected to the main protective earthing terminal.A hinge would
certainly not be regarded as a reliable connection.
As far as your door is concerned, is there any single insulated hazardous
voltage wiring likely to contact
A limited amount of information may be found in CENELEC Report R079-001:1998
Guide to achieving compliance with EC directives for alarm systems
I don't have a copy, however.
Regards,
John Crabb, (Product Safety) ,
NCR Financial Solutions Group Ltd., Discovery Centre,
3 Fulton Road,
You will have noted in IEC 60950-1 Clause 4.2.5 Impact Test, that it states
the test is not applied to flat panel displays or to the platen glass of
equipment (for example, copying machines).
The waiver for flat panel displays appeared in the third edition of IEC
60950 - some time ago I trawled
As a matter of interest, I have read that the enlargement of the EU is going
to provide many, many jobs as translators, and there are anticipated to be
major problems ahead since for some language combinations it is expected
that there is
no-one trained as a translator, and therefore they would
In directive 93/86/EEC (relating to batteries containing certain dangerous
substances),
it says the symbol shall cover 3% of the area of the largest side of the
battery
or accumulator, up to a maximum size of 5 cm x 5 cm. For cylinrical cells
the symbol
shall 3% of half the surface area of the
Cenelec document HD 472 S1, 1989, nominal voltages for low voltage public
electricity supply systems
is the document that states for the first step, namely to 230V +10% -6%,
Note: The dead-line
for the completion of the first step is envisaged for 1995.
It also states that The transition period
Annex ZC (Informative) A-Deviations, in EN 60950-1, states
Clause 1.5.1 Deviation
Sweden (Ordinance 1990:944)
Add the following:
NOTE In Sweden, switches containing mercury such as
thermostats, relays and level controllers are not allowed.
Switzerland (Ordinance on environmentally hazardous
Has anyone encountered problems in the use of
pre-plated sheet steel in IT equipment metalwork ?
Typically such material is cheaper to use than
having to plate parts after they have been produced,
but there may be issues with sharp edges produced
when the material is punched out, and with rust
You can say that electricity in a bathroom can be dangerous,
and in the UK, we are very cautious in this respect:
You don't have a wall mounted light switch in a bathroom,
it is either outside the room, or the light is operated by
a pull cord operated switch on the ceiling.
You are not allowed to
Annex ZC of EN60950-1, IT Equipment - Safety, states:
Sweden (Ordinance 1990:944), In Sweden, switches
containing mercury such as thermostats, relays
and level controllers are not allowed.
Regards,
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd.,
This is way out of my normal range of Product Safety experience,
but I can say BE VERY CAREFUL with liquid nitrogen.
My memory bank reminded of a fatality in Scotland not that
long ago, and after a short search on liquid+nitrogen+death,
I came up with the following :
I agree with Rich on the moral obligation a
company has to avoid injury to those who
use its products.
Every year I give a lecture on Product Safety
to manufacturing engineering students at our
local university. This is what I say in answer to
Why have Product Safety ? -
As well as the
I have never heard of an inlet with provision for a spare fuse.
Are you sure it wasn't a double pole fused inlet ?
(SOME PEOPLE say double pole fusing is a requirement of IEC 60950,
but it ain't necessarily so).
Regards,
John Crabb,
NCR Financial Solutions Group Ltd., Discovery Centre,
3
Rich Nute said : -
For grounded (Class I) equipment for the home, the UL leakage current
is 0.5 mA. (This is NOT a 60950 limit.)
UL reasoned that if 0.5 mA arises from both real and stray capacitance,
then, for double-insulated (Class II) equipment, the current should be
one-half of 0.5 mA
Answer is presumably in ISO 1000, specification for
SI units and recommendations for the use of their
multiples and of certain other units.
Regards,
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Discovery Centre,
3 Fulton Road, Dundee,
The formula for calculating the temperature rise of a winding
can be found in Annex E of IEC 60950 - and all the experts in
TC 74 can't be wrong ?? (I also found the same formula in my
1985 issue of IEC 380.
Different temperature coefficents for copper have been quoted,
and as far as I can
If you plot resistance of copper vertically, against
temperature horizontally, and extend the graph
backwards, the point of intersection with the
horizontal axis is found to be -234.5 degrees C.
(Got this out of my early years text book which
I keep at my desk !)
Hence for a standard copper
I can imagine that it is a perfectly reasonable requirement
that electricity meters be required to operate correctly
when subjected to high magnetic fields, to overcome any
likely fraud attempts by enterprising consumers with
permanent magnets, trying to reduce their electricity bills.
I suspect
I have just obtained the above draft for public comment,
which is the BS implemenation of Draft International
Standard ISO/IEC 17024 General requirements for bodies operating
certification schemes for persons. Apparently the circulation
of this draft ISO/IEC standard is also a CEN(ELEC) parallel
1.1.2 of EN 60950-1:2001 states requirements additional to those
specified in this standard may be necessary for .. equipment
intended for use where ingress of water is possible; for
guidance on such requirements and on relevant testing, see
annex T. Annex T, which refers to IEC 60529, is
: 25 March 2002 15:28
To: Crabb, John
Cc: emc-p...@ieee.org
Subject: RE: chassis bonding - star washers enough?
Hi John,
You wrote:
We use screws which have combined hex/posidriv heads with
serrations under the head, which eliminates the need for star washers.
We find these work very well for zinc
Clause 1.7.8.2 Colours, of IEC 60950-1 states
Where safety is involved, colours of controls and indicators
shall comply with IEC 60073. Where colours are used for
functional controls or indicators, any colour, including
red, is permitted provided that it is clear that safety
is not involved.
Surely the requirement is as found in the Guideinfo for
CCN (AVLV2) Appliance Wiring Material, namely ;
The Recognition Mark of Underwriters Laboratories, Inc.
(illustrated below) on the attached tag, the reel or the
smallest unit container in which the product is packaged
is the only met.. -
IEC60950 has a requirement (1.6.4) that the neutral conductor,
if any, shall be insulated from earth and from the BODY
throughout the equipment as if it were a line conductor. Components
connected between neutral and earth shall be rated for the
line-to-neutral voltage.
Typically I would expect
According to World Electricity Supplies from BSI,
voltage is 200/100, 60 Hz.
We have certainly produced 100V 60 Hz specials for
Japan.
Regards,
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Discovery Centre, 3 Fulton Road,
Dundee, Scotland, DD2
As a matter of interest, when you order a free amendment or
corrigendum from BSI, you have a reasonable chance of being
supplied with the whole standard !! (which makes my day : )
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Discovery Centre,
There are a series of ENs, 50121, relating to EMC
requirements for railway equipment.
That's all I know - I just noted in my records back
in 1997 that they were starting to appear.
I also note in EN 61000-4-8 Power frequency magnetic
field immunity, that 1 A/m corresponds to a free space
I seem to recollect that I have previously pointed out
that the LVD states electrical equipment which complies
withharmonised standards shall be regardedas complying;
and standards shall be regarded as harmonized once they are
drawn up by common agreementand published under national
Just to clarify the position in the UK, although it was stated below
that the nominal voltage is 415V, I am almost certain that the DECLARED
VOLTAGE is 400V. I base this on the fact that domestic consumers
were advised that the declared voltage changed from 240V to 230V,
and 230 X 1.732 = 400V,
I would agree that whether a safety standard is published
in the OJ against the LVD should never be an issue.
I would remind everyone that the LVD states electrical
equipment which complies with the safety provisions of
harmonized standards shall be regarded...as complying.
FOR PURPOSES OF
Before we start cutting our budgets for the purchase of standards,
I read in another CEN announcement ;
eEurope standards are defined in workshops whose agreements will
be made available for downloading free of charge from the CEN web
site.
So it may just be CEN Workshop Agreements (CWAs) that
John, I have forwarded this information to the chairman of
BSI committee EPL/74 (which deals with EN60950), with the
suggestion that CENELEC be asked to get EN60529 removed
from the list of LVD notified standards. We'll see what
happens.
On the same subject, TC74 is working on requirements
Bill - you absolutely correct in describing the North American system as
single-phase, 3 wire. After all, that is how it is described in Annex V,
Figure V.4 of IEC60950:1999 - and there is NO WAY that IEC TC74
could be wrong, is there ? (especially since the US committee must
have voted yes, to
ANSI/NFPA 30A is the Automobile and Marine Service Station Code,
and has a table of Electrical Equipment Classified Areas - Service
Stations, which described the extent of classified areas adjacent
to pumps and underground tanks.
For our Automated Teller Machines, I always ask the customer to
Almost certainly the answer will be found in BS1363 Part 1,
Specification for rewirable and non-rewirable 13A fused plugs.
(I assume you are referring to UK plugs, as I don't know of
any other plug with a fuse).
My copy of BS1363 is rather old, but there is a table which shows
a 3A (5A) fuse
There are many EMI filters on the market with a discharge resistor across
line and neutral
to discharge the capacitor(s). The filter we use has a one megohm resistor
built in.
IEC60950 requires that capacitor exceeding 0.1uF should have a means of
discharge resulting
in a time constant not
Far be it from me to criticize UL Listed products,
or UL standards, but it seems to me that the plug in
question was not suitable for its intended use.
I can recall conducting a humidity test on one of our
products, and at the conclusion of the test, it failed
a dielectric test, and I traced the
Would anyone have any guidelines on how to design computer graphics
in such a way to avoid inducing Photo Sensitive Epilepsy in anyone
who suffers from that complaint ?
Regards,
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Kingsway West,
Far be it from me to nit-pick, but to say in a standard that
the tests specified in this annex SHOULD be carried out by the
manufacturer on each luminaire after production, doesn't sound
like a normative requirement. They should have used SHALL.
But maybe it is an informative annex ?
Regards,
I hesitate to remind you all, but if anyone has a problem
interpreting the requirements of IEC 60950, there is
the TC74 Chairman's Advisory Panel.
Briefly, the procedure is as follows :
Questions for interpretation should, as a minimum
- define the problem, making reference to a specific
There are stability tests in UL751 - Vending machines,
which I have in my fantastic filing system. (Just in case
anyone thought my products - Automated Teller Machines,
were vending machines).
I can't be sure if they are also in UL541 - Refrigerated
Vending machines - since I don't have a copy.
Figures I have entered below are from the 1996 edition of the
BSI publication World Electricity Supplies.
Regards,
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2
3XX
E-Mail :john.cr...@scotland.ncr.com
Tel:
As a previous reply has suggested, but not in the same words,
surely one question that has to be considered is whether this hinged
panel is required to be earthed. The requirement in UL60950 2.6.1 a)
refers to accessible conductive parts that might assume a HAZARDOUS
VOLTAGE in the event of a
I don't know if you have to fit a plug, but I can
certainly tell you that our USA customers would be
VERY UNHAPPY if we supplied a product without a plug.
I certainly have the impression that fitting a plug
in the USA is not something that people expect to
have to do.
Regards,
John Crabb,
The scope of EN60950 Safety of IT Equipment reads :
SAFETY OF INFORMATION TECHNOLOGY EQUIPMENT -
1 General
1.1 Scope
1.1.1 Equipment covered by this standard
This standard is applicable to mains-powered or
battery-powered information technology
equipment, including electrical business equipment
I certainly have a lot of small plastic parts in my products which I
consider to be exempt and are not described in any procedure - and they
may well be a lot bigger than your standoff !!
I certainly think your agency is not-picking !!
One point to consider is that I write the procedure for UL
I cannot answer for all the countries involved,
but I can quote the document which was delivered
to my home address in 1995 from my electricity
supplier (Scottish Hydro-Electric), and which,
naturally, I brought into work and filed under
230V harmonization : -
DECLARED NOMINAL SUPPLY VOLTAGE
We are fortunate in that we always get the lab personnel to
come to our facility to test our products. This has many
advantages, the main ones being that any issues can be cleared
up with the design engineers, and you don't let the lab people
go until they agree to approve your product !!
The ECMA 2000 Memento (their yearly handbook)shows ECMA-97
as withdrawn, with no note of any equivalent international
or European standard. There is no copy of ECMA-97 on the
CD-ROM distributed with the 2000 ECMA Memento. Unfortunately
I have disposed of my previous ECMA CD-ROMs, but maybe
This directive states : -
that employers must obtain and/or use work equipment which, if provided to
workers in the undertaking and/or establishment for the first time after 31
December 1992, complies with the provisions of any relevant Community
directive which is applicable.
I read this as
As a member of the British EPL/74 committee, I can say that I
know of no plans to issue an IEC standard equivalent to EN50116.
Historically, almost certainly ECMA will have produced their standard
and then given it to CENELEC who issued it as EN50116.
I don't know if IEC would entertain
I'm sure we have been through this all before, but here goes :
For equipment certified by UL and CSA (and I assume by other
agencies, but I have no personal experience), the End of Line
Tests will be specified as part of your certification.
For Europe, there is EN 50116, which defines the
One reason I have heard - and I can't recall where, was simply
that the equipment (in particular - toys) had originally been
tested and found to comply with the appropriate requirements,
when tested with zinc carbon batteries, and manufacturers are
loath to claim that their equipment is ok
Try EN 61011, Electric fence energizers.
Safety requirements for mains-operated electric fence energizers.
EN 61011-1 Safety requirements for battery-operated electric
fence energizers suitable for connection to the supply mains.
EN61011-2 Safety requirements for battery-operated electric
fence
URL for required Directive - happy reading !
http://europa.eu.int/eur-lex/en/lif/dat/1996/en_396L0029.html
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2
3XX
E-Mail :john.cr...@scotland.ncr.com
Tel: +44
In the latest edition of EN 60950:2000, Safety of IT Equipment,
Annex H, Ionizing Radiation, you will find the following changed
text : -
At any point 10cm from the surface of the OPERATOR ACCESS
AREA, the dose rate shall not exceed 1uSv/h (0.1 mR/h) (see note).
Account is taken of the
EN 60721-3 = Classification of groups of environmental parameters
and their severities.
According to the BSI catalogue, EN 60721-3-2 is identical to
IEC 60721-3-2, Transportation, defines conditions to which a product
is subjected while being transported from one place to another after
being
The use of the colour red for on/off switches is now enshrined in
history, and I see no reason to outlaw the practice, provided it
does not create a hazard. ( I must be getting old, if I am
starting to use the it has always been this way argument).
Looking in catalogues for switches in common
)1382-592289 (direct ). Fax +44 (0)1382-622243. VoicePlus
6-341-2289.
-Original Message-
From: Paul J Smith [SMTP:paul_j_sm...@notes.teradyne.com]
Sent: 07 January 2000 17:13
To: Crabb, John
Cc: emc-p...@ieee.org
Subject: RE: Inquiry on Restrictions and Bans of Mercury
As the worlds No. 1 manufacturer of ATMs, and probably the manufacturer
of the ATM in question, I have received the following information from our
people in Hungary : -
The scanned ATM receipt is NOT REAL, the date on it had been manually
altered, but it is not a good joke, it is a serious
As a manufacturer of Automated Teller Machines (ATMs)
which are subject to considerable mechanical abuse, we
have not found any particular standards detailing tests for
such abuse. There are requirements for impact tests for the
exterior of enclosures which would give access to hazards,
in IEC
I use a Yokogawa Type 3226 Universal Leakage Current Meter
which is quite old, (10 years ++) and can measure ac current,
dc current, and dc+ac current, with input resistances of 1,
1.5 and 2 kohms.
I also have a Simpson 229-2 (also quite old) which gives me very
similar results to the above.
World Electricity Supplies (from BSI) gives household voltage as
220/127V, +5%. -7.5%.
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2
3XX
E-Mail :john.cr...@scotland.ncr.com
Tel: +44 (0)1382-592289 (direct ).
From IEC 74/510/CD, draft amendment to IEC 60950,
Material flammability classifications,
HBF replaced by FH-3. The new definitions are not in all
cases identical to the earlier ones.
I imagine the -40 in the FH3-40 you refer to is the burning
rate of 40mm/min specified for HBF.
A certain
Sorry to add to the confusion, but the British trade
association FEI publishes a document on periodic
safety checks for business equipment, which includes
a table of conductor sizes and fuse sizes
for British plugs, with the following note:
BS 1363 specifies only the use of 3 A or 13 A fuses.
In the BSI catalogue I have found : -
BS EN 1264 Floor Heating. Systems and Components
comprises :
BS EN 1264-1:1998 Definitions and symbols
BS EN 1264-2:1998 Determination of the thermal output
BS EN 1264-3: 1998 Dimensioning
All the above BS are identical to the EN.
There is also a BSI CP 1018
I presume you have a copy of PD 6608:1997 = CENELEC REPORT
R079-001:1996, Guide to achieving compliance with EC directives for
alarm systems. (I don't know if a more up-to-date version exists).
I bought this document to see what it said about safety, but it just
said EN 60950 shall apply.
I am
BSI World Electricity Supplies quotes +/-10% for overhead cable and
+/-7% for underground cables for 220V in Argentina.
For the US, there are tolerances quoted for some cities.
Worst is +/-10% for Pittsburgh for power as opposed to lighting.
Regards
John Crabb, Development Excellence (Product
I am going on vacation (to Florida!) tonight, but just to stir things up,
WHY ALL THESE NEVER-ENDING DISCUSSIONS ON IEC127
and UL FUSES.
It IS possible to get products approved by UL and European agencies,
without using different fuses. We buy power supplies and monitors,
with UL and at least
For my sins, I am on the BSI committee which provides the British
input to IEC 60950, and I have every sympathy with you, Nick.
I can advise from memory, that the British committee usually tries
to ensure that all the requirements end up in IEC 60950, where
reasonably practical. I seem to
For everyones information, the wording of the Danish Special
National Condition, as found in Annex ZB (normative) of
BS EN 60950 = EN 60950 is :
Clause 1.2.4.1, In Denmark, certain types of Class 1 appliances
(see subclause 3.2.1) may be provided with a plug not
establishing earthing
If you perform a limited current test on your inverter, as per
IEC 60950 2.4.2, you will probably find it meets these requirements,
which means that theoretically Operator access is allowed - though
you'll definitely feel it if you touch it :( .However, it does mean that
if the invertor output
UL1950 states :
4.4.5.2 Components not requiring a fire enclosure
-components in a SECONDARY CIRCUIT supplied by a limited power
source complying with 2.11, provided that :
-the components are mounted on materials of FLAMMABILITY
CLASS V-1 or better, and
-the wiring used in such circuits is
I recalled that this subject had been discussed in depth at a BSI
committee meeting, but had to dig back to 1995 to find it.
The BSI committee stated, in response to any enquiry such as yours : -
---
Please be aware that
The standard which applies is IEC 60384-14 Fixed capacitors for
use in electronic equipment-Part 14, Sectional Specification;
Fixed capacitors for electromagnetic interference suppression and
connection to the supply mains.
I only have a draft in my possession. It states Capacitor of Class X,
The original post said :
EN 50116 for ITE specifies the earthing terminal or earthing contact may not
exceed 0.1 ohms when 1.5 times the current capacity of hazardous circuits is
applied, but not more than 25 A (ac or dc) for 60 seconds.
My copy of EN50116 specifies the time as being for the
Since this is a UK question, The Provision and Use of Work Equipment
Regulations 1992 (SI 1992 No. 29323) would seem to apply. It states
under Conformity with Community requirements 10 - (1) Every employer
shall ensure that any item of work equipment provided for use in the
premises
or
Doug, I would have thought you would already have come across the
symbol for the crossed-out wheeled bin in the directive 93/86/EEC
which adapts to technical progress Council Directive 91/157/EEC
on batteries and accumulators containing certain dangerous substances,
the dangerous substances being
You could try asking CSA for a copy of their
CSA 950/UL1950 Design Manual, which includes a fair
amount of the French marking text (and is quite a good
short list of basic design requirements). I would expect that
this document would be free.
I am a little puzzled by a note in the rather old
As far as I am aware, the FDA requirements (21CFR) relate to the emission
of X-rays from CRTs within monitors. We always state that any LCD displays
within our products are therefore exempt from the FDA requirements.
I also have on file a letter to all manufacturers and importers of
television
I agree with Rich's suggestion re treating this as a Limited Current
Circuit, and
carrying out the test in 2.4 with a 2000 ohm resistor. We have done this for
several LCD displays we use, to satisfy UL, and they seem happy to accept
this.
We also short circuit the transformer output to prove
My 1996 World Electrical Supplies says 240 V +/- 6%
Regards,
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2
3XX
E-Mail :john.cr...@scotland.ncr.com
Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243.
...@bev.etn.com]
Sent: 21 April 1999 16:18
To: 'Crabb, John'; 'discussion group'
Subject: RE: What color is neutral.
Mr. Crabb,
I appreciate your spending 2c (or is that 2p!) on this issue.
As the 'thread' initiator, I hope I can trouble you with a follow-up.
As you and Mr. John Woodgate
In our detachable cord connected products, we use American power cords
with black, white, green wires on 120V units which are UL Listed, CSA
Certified; and European cords with brown, blue, green/yellow wires on 230V
units.
(As an aside, note how UL and CSA choose to ignore the UL1950 requirement
I managed to find in the top 6 inches of my in-tray (piled 18 inches high),
the
Subject 1950 and 1459 letter from UL dated October 26, 1998;
Subject: New Issue of Standardized Appendix Pages.
These are for ITE (NWGQ), Power Supplies for ITE (QQGQ); Telephone
Appliances (WYQQ); and Power Supplies
We use a Yokogawa 3226 Universal Leakage Current Tester
together with a 3227 Test Box. The meter has both an AC and
an AC+DC current range, and switchable 1K, 1.5K, and 2K
input resistance. The test box has a polarity and an on-off switch to
simplify testing, and has a US mains socket into
I have a file at least an inch thick on company name change, since
NCR changed to ATT and back again. Certainly it was simple as far as
UL and CSA were concerned. For UL you will have to notify them of the
change of Listee, Applicant, Manufacturer, etc, as appropriate for each
volume of your
Brian, is case you are concerned by the statement that EN 60945
...is almost the same as IEC 60945, according to my BSI catalogue,
BS EN 60945 (the British implemetation of EN 60945) is identical in
every detail to EN 60945 and IEC 60945, therefore EN 60945 and
IEC 60945 are identical (in
Briefly, the HAR mark means the cordage has been approved by one
of the members of the CENELEC HAR scheme, whereby cordage is
tested to Harmonized standards, and is accepted by all of the members
of the scheme without further hassle. A manufacturer can only get a
HAR mark if he is in a country
NCR keeps a copy of the Declarations of Conformance on file in Europe
(in London), signed by a legal person (our International Intellectual
Properties
Counsel) who is based in London. It is also signed by the Director of
Operations of the US manufacturing plant.
John Crabb, Development Excellence
My company (NCR) ships automated teller machines worldwide. Our policy
on plugs is simple: -
If the product is 120V, we supply a UL/CSA cordset with a NEMA plug,
and if the product is 220/230/240V, we supply a HAR cordset, WITHOUT
A PLUG, together with a one page chart showing the plugs for
The third edition of IEC 60446 Basic and safety principles for
man-machine interface, marking and identification -
Identification of conductors by colours or numerals is at the
FDIS (Final Draft International Standard) stage, with voting
terminating on December 15. There is parallel voting for
I would also be interested to know what everyone is doing (or not doing !!).
As far as I can gather, everyone is ignoring this issue, as it is just so
ridiculous.
After all, the only way you can prove that a LED is Class 1 or below is to
do
the measurements - and I'm sure most of us don't have
All we do is to specify the required plastic material by Manufacturer,
generic name,
and specific grade on our drawings.
From time to time, the FUS inspector will pick a part from our assembly
line, and check the
drawing in our print file to ensure that it calls up a material that meets
the UL
In the BSI publication World Electricity Supplies, 1996 (probably
not the latest), the UK variation is given as +/-1%, while the highest
given for US (there are different figures for different states) is +/- 0.3%.
John Crabb, NCR Financial Solutions Group Ltd, Dundee, Scotland.
-Original
I have come across similar incidents, and guess that the decoupling
capacitors have been installed with reversed polarity. The capacitors
do not always burst into flame when power is supplied - it may take
some time - and if the equipment is not powered up for very long
while it is being built
Just noticed the following on newsgroup comp.std.internat today: -
The European Telecommunication Standards Institute (ETSI) has decided
to put all European Telecommunication Standards freely accessible
on the Web:
http://webapp.etsi.org/publicationssearch/
http://www.etsi.org/
UL 1778 UPS Equipment requires that a fixed UPS has a disconnect
switch for its output (or a cord and plug or receptacle on the output).
Otherwise (according to UL 1778) the UPS instruction manual
should require that you provide a disconnect device on the
UPS output.
However, these
within five minutes of activating the remote
emergency power off circuit. NEC 645-11, CEC 14-700
John Crabb, Product Safety Engineer,
NCR Financial Solutions Group Ltd., Dundee, Scotland.
-Original Message-
From: CTL [SMTP:c...@prodigy.net]
Sent: 26 October 1998 14:11
To: Crabb
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