RE: FDA Laser Requirements

[Steve Hsu]

Hi, Rich:

I believe it's a typo error there. It should read as 1002.1, 21CFR1002.1(c)
and Table 1 show the Applicability.


Regards,


Steve Hsu
Sr. Quality Engineer
Pine Photonics Communications
s...@pinephotonics.com



From: richwo...@tycoint.com [mailto:richwo...@tycoint.com]
Sent: Wednesday, March 05, 2003 8:56 AM
To: emc-p...@majordomo.ieee.org
Subject: FDA Laser Requirements



21CFR1002.30(b) refers to 1002.61 which does not exist. Does anyone know the
correct reference?


Richard Woods
Sensormatic Electronics
Tyco International



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Military ESD Specs

[Locke, Darrell]

Members,

Does anyone know the applicable military specs (US) for personal ESD (PESD)
and helicopter ESD (HESD) are?  These are not covered in MIL-STD-461.

Thanks

Darrell Locke
Advanced Input Devices


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RE: Ethernet coax connection

[neve...@attbi.com]

The one-point connection od the 10 Base- coax shield is specified by IEEE 
standard 802.3. In my (2000) revision, it is e.g. in paragraph 8.7.2.2., page 
158.

"to prevent the building up of voltages that may result in undue hazard to 
connected equipment or to persons."


However, when twisted-pair (differential) interface is used in 10/100/ and
1000 
Mbps Ethernet, the cabling may be unshielded twisted pair (UTP) or shielded 
twisted pair (STP). There isn't such a requirement to connect the shield at 
only one side in that case. E.g. section 41.4.2.2 of the same standard 
describes it, and it says that if the shielded cable is used, then 

"the shield may be grounded at both ends according to local regulations
and 
ISO/IEC 11801, 1995, and as long as the ground potential difference between 
both ends of the network segments is less than 1 Vrms."


Neven
> 
> Rich,
> 
> I think you must be correct.  I do have anecdotal evidence of persons being
> "knocked on their butts" by grabbing hold of an Ethernet coax in a large
> facility and trying to connect it to a computer.
> 
> My experience is in EMC and the 10Base2 Ethernet (coax) is a persistent
> offender.  (Actually, the twisted pair stuff has its own set of EMC
> problems.)
> 
> Regards,
> 
> Jim
> 
> 
> Jim Knighten, Ph.D.
> Teradata, a Division of NCR   http://www.ncr.com
> 17095 Via Del Campo
> San Diego, CA 92127
> USA
> Tel: 858-485-2537
> Fax: 858-485-3788
> jim.knigh...@ncr.com
> 
>  -Original Message-
> From: Rich Nute [mailto:ri...@sdd.hp.com] 
> Sent: Wednesday, March 05, 2003 4:31 PM
> To:   Knighten, Jim L
> Cc:   ken.ja...@emccompliance.com; emc-p...@majordomo.ieee.org
> Subject:  Re: Ethernet coax connection
> 
> 
> 
> 
> Hi Jim:
> 
> >   It is a potential shock hazard if the coax run is long and runs from
> >   building to building (for instance) where the ground potentials may be
> >   different in the different buildings.  One can develop a large potential
> on
> >   the shield of the cable, so that if you put yourself between the cable
> >   shield and ground you may get a strong shock.  That is the reason for
> >   isolating the shield from more than one direct connection to ground.  It
> is
> >   a real issue.  
> 
> I don't believe the issue is that of electric shock.  I don't believe the
> current and resistance of the neutral are high enough to develop 30 volts
> (the shock hazard limit).
> Instead, I believe the problem is that, with two connections, the shield is
> in parallel with the neutral.  That means that some of the neutral current
> will pass through the shield, and will likely open a PWB trace somewhere.
> In the process, the PWB trace heating may start a fire.
> I believe the circuit is:
> (You may not be able to read this schematic if your mail reader is not set
> for plain ASCII text.)
> 
> 
> L  Bldg A
>  +-++
>  | ||
>  | ||
>  | |   | |
> (~) 120 V  |   | | load
>  | |   | |
>  | ||
>  |N||
>  +-++-+-+
>  |utility  |   || Bldg A  |
>  |ground   |   || ground  |
>  |rod  |   || rod |PE   BNC shield
>-   |   |  -   +->>---+
> ---|   |   ---   |
>  - |   |-|
>|   | |
>|   | |
>|   | |
>|   | L   Bldg B  |
>++|
>|||
>|||
>|   | |   |
>|   | | load  |
>|   | |   |
>|||
>| N  ||
>++-+-+|
> | Bldg B  |  |
> | ground  |  |
> | rod |PE|
>   -   +->>---+
> ---  BNC shield
> -
> 
> 
> You can see from the schematic that the shield is in parallel with both the
> neutral and the earth-ground.  Being in parallel, it will carry some of the
> neutral current, depending on the respective resistances.
> Because of both the neutral and the earth-ground, the voltage should never
>

New countries that will accept the CE Mark

[Collins, Jeffrey]

Group,

Does anyone have any recent updates on the following countries legislation
to accept the CE mark?
If/when this is complete, will the CE mark have equal weight as their
national mark? 


* Bulgaria

* Czech Republic 

* Hungary 

* Romania

* Slovakia

* Slovenia

* Poland

* Turkey


Thanks,


Jeffrey Collins 
Sr. HW Engineering Manager 
EMC/ NEBS/ Reliability/ Safety
CIENA  Core Switching Division
5965 Silver Creek Valley Rd. 
San Jose, CA. 95138
(408) 571-3002, Fax (408) 965-2705
jcoll...@ciena.com
http://www.ciena.com



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RE: Ethernet coax connection

[Grasso, Charles]

I seem to recall that -years ago-
IBM had an interface DC voltage spec.
IBM required that BEFORE attaching a
building-to-building interface cable to
an EUT, that a DC voltage measurement be
made between the shield of the cable
and the EUT chassis. If the voltage exceeded
1.5V (I think) the installer was instructed
NOT to attach the cable. 

If this problem has gone away - maybe to better
building codes - the hurrah!. This was not 
always the case.


Best Regards
Charles Grasso
Senior Compliance Engineer
Echostar Communications Corp.
Tel:  303-706-5467
Fax: 303-799-6222
Cell: 303-204-2974
Email: charles.gra...@echostar.com;  
Email Alternate: chasgra...@ieee.org
 



From: Knighten, Jim L [mailto:jk100...@teradata-ncr.com] 
Sent: Thursday, March 06, 2003 10:17 AM
To: john...@itesafety.com
Cc: emc-p...@majordomo.ieee.org
Subject: RE: Ethernet coax connection



I knew that I was headed for trouble when I responded to Ken Javor original
question about EMI frustrations with 10Base2 Ethernet.  I figured the safety
guys would pummel me a little - and I accept the comments.  However, I
couldn't resist since I have experienced the same EMI frustrations.

Nevertheless, good EMI engineers are sometimes faced with an existing design
that uses 10Base2 (legacy, if you will) and has the severe EMI problem that
an experienced EMI engineer could anticipate.  Ignoring it is unacceptable
>from a regulatory point of view (in the case of commercial products), or
>from other spec and/or contract reasons in the government world.  Many, if
not most of the practical solutions appear to violate either the letter or
the spirit of the Ethernet 10Base2 spec.  This puts the EMI engineer in the
same seemingly untenable spot that Ken Javor appeared to be in yesterday.
I've been there and I empathize.  

Jim


Jim Knighten, Ph.D.
Teradata, a Division of NCR http://www.ncr.com
17095 Via Del Campo
San Diego, CA 92127
USA
Tel: 858-485-2537
Fax: 858-485-3788
jim.knigh...@ncr.com

 -Original Message-
From:   Robert Johnson [mailto:john...@itesafety.com] 
Sent:   Wednesday, March 05, 2003 9:53 PM
To: Knighten, Jim L
Cc: emc-p...@majordomo.ieee.org
Subject:RE: Ethernet coax connection

 << File: Robert Johnson.vcf >> If you have shock level differences between
the grounds in two different buildings, either an entire building isn't
connected to an earth electrode, or someone is paying a whopping electric
bill to heat up mother earth. I suspect the shock situation you were talking
about was a power cross condition, either to the cable or within equipment.
I hope it was diagnosed and fixed.

The voltage differences between two buildings are generally very low, on the
order of a couple volts, but due to fractional ohm impedances are capable of
very high currents. Building maintenance procedures should routinely be
checking for ground currents since they indicate faults in the power system.

Note that in accordance with IEC 62102, 10base2 is an SELV circuit and
should not be used for exposed plant (between building) wiring. Ethernet
distance specs and application recommendations also go against exposed plant
wiring. Ethernet 10base5 is considered a TNV-1 circuit and suitable for
exposed plant use, is insulated and requires single point grounding. Optical
fiber is a better recent development and the best answer for exposed plant
lines these days.

Note that IEC 62102 provides an extensive list of interconnect circuit types
and what category they fit into with regard to shock level (SELV, TNV,
hazardous, etc). It's an important reference for any engineer designing
interconnect circuits in determining isolation needs.


Bob Johnson
ITE Safety
 


From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Knighten, Jim L
Sent: Wednesday, March 05, 2003 7:51 PM
To: Rich Nute
Cc: ken.ja...@emccompliance.com; emc-p...@majordomo.ieee.org
Subject: RE: Ethernet coax connection


Rich,

I think you must be correct.  I do have anecdotal evidence of persons being
"knocked on their butts" by grabbing hold of an Ethernet coax in a large
facility and trying to connect it to a computer.

My experience is in EMC and the 10Base2 Ethernet (coax) is a persistent
offender.  (Actually, the twisted pair stuff has its own set of EMC
problems.)

Regards,

Jim


Jim Knighten, Ph.D.
Teradata, a Division of NCR http://www.ncr.com
17095 Via Del Campo
San Diego, CA 92127
USA
Tel: 858-485-2537
Fax: 858-485-3788
jim.knigh...@ncr.com

 -Original Message-
From:   Rich Nute [mailto:ri...@sdd.hp.com] 
Sent:   Wednesday, March 05, 2003 4:31 PM
To: Knighten, Jim L
Cc: ken.ja...@emccompliance.com; emc-p...@majordomo.ieee.org
Subject:Re: Ethernet coax connection




Hi Jim:

>   It is a potential shock hazard if the coax run is long and runs from
>   building to building (for instance) where the ground potentials may be
>   different in the different buildings.  One can develop a l

RE: Ethernet coax connection

[david_ster...@ademco.com]

ANSI/IEEE 802.3 specifies 10Base2 earthing at some point along the cable,
but not at any node.  10Base2 nodes typically are an isolated (DC/DC + level
shifter) 9-volt part of the PBWA with a high resistance connection to
chassis.  

[RF radiation is higher and RF immunity is lower than 10BaseT.  The 'shield'
is a conductor so it radiates if not earthed.]  

To reduce emissions ground the cable at a single point (typical office
installations had punch blocks in the wiring closet); additional points may
introduce ground loops.  Other replies suggest an AC ground...you need to
eliminate odd-order harmonics (typically 5th to 13th).  Also check COTS
10Base2 component specifications:  some were only Class A.

It is difficult dealing with legacy technology.  Choices of COTS 10Base2 are
limited, EMC modifications change it to 'custom.'

David


From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: Wednesday, March 05, 2003 3:38 PM
To: emc-p...@majordomo.ieee.org
Subject: Ethernet coax connection



Question for list members:

Background:  I am troubleshooting a complex integration of military hardware
and COTS.  One COTS piece of equipment has an RG-58 coaxial connection, but
the coax connector is an isolated feedthrough bnc.  From a radiated
emissions point-of-view, that is hurting us.  One of the engineers here said
that is part of the spec - Ethernet shields are not supposed to be chassis
grounded.

Question:  Can someone please explain the reason for that, and how this is
usually handled to minimize radiated emissions?

Thank you.

Ken Javor
EMC Compliance
Huntsville, Alabama
256/650-5261




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Need reliability engineering consultant or firm

[Denomme, Paul S.]

Can anyone recommend a consultant or a company that can help me with
reliability requirements/life expectancy requirements? 

Regards,

Paul S. Denomme
Design Engineer
Viasystems 
804-226-5155
804-226-6056(fax)



From: John Woodgate [mailto:j...@jmwa.demon.co.uk]
Sent: Tuesday, March 04, 2003 8:17 AM
To: emc-p...@majordomo.ieee.org
Subject: Re: RADIATED IMMUNITY - Some Actual Measurements of FS



I read in !emc-pstc that drcuthbert  wrote (in
)
about 'RADIATED IMMUNITY - Some Actual Measurements of FS' on Tue, 4 Mar
2003:

>Just remember, in words of N6SU "if you can't see it it can't hurt you".

Doesn't work for gamma rays.(;-)
-- 
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk

Interested in professional sound reinforcement and distribution? Then go to 
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!


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Need 230VAC-115VAC 500VA Step-down Isolation Transformer with UL, cUL, and CE

[Bill Johnson]

Hi!

I apologize if this is an inappropriate question for this forum.

I am trying to select the above component for a product we are designing.  

I have found transformers with no approvals, one with UL and cUL, but not
CE.

Any advice on where to look or how to select such a component would be a
great help!

Thanks!



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Dual LISN vs Single LISN...

[kaan.l.greger...@l-3com.com]

Hello Group,

I am considering purchasing a dual LISN (two LISN networks within a single
metal enclosure).  Having used single LISNs for years, I am concerned that
the dual LISN may be problematic for internal crosstalk/noise due to the
close proximity of the independent LISN networks within the same enclosure.


Does anyone have experience or recommendations that they could share with me
regarding Dual LISNs vs Single LISNs?

Thanks,

Kaan Gregersen



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Austel approved modem

[Chris Maxwell]

Hello,

We are looking for a source for an Austel approved modem (56K) for an
Australian customer.

The form factor for this modem could be one of the three following packages. 
I will list them in order of preference:

1.  A cPCI compatible card.
2.  A rackmountable, stand-alone unit powered from 48VDC
3.  An AC powered, stand-alone unit.

Anybody have any suggestions?  I was half hoping that someone in the group
worked for a company that made such an animal.

Thanks in advance for any leads you may be able to provide.

Chris Maxwell | Design Engineer - Optical Division
email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024

NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA
web www.nettest.com | tel +1 315 797 4449 | 





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Re: Ethernet coax connection

[Ken Javor]

Thanks to all who answered in MINUTES assisting an EMI troubleshoot on
something that is of great national value.

This forum is a tremendous resource!




on 3/5/03 4:46 PM, Stone, Richard A (Richard) at rsto...@lucent.com wrote:

> we've had good success with the
> built capacitance of 9000pf as well,
> depending on test being discussed and
> frequency, certain cap. values from the shielded
> ring of the UNgrounded ring to earth works well
> for low freq..< 30 mhz.
> Richard,
> -Original Message-
> From: Knighten, Jim L [mailto:jk100...@teradata-ncr.com]
> Sent: Wednesday, March 05, 2003 4:12 PM
> To: Ken Javor; emc-p...@majordomo.ieee.org
> Subject: RE: Ethernet coax connection
> 
> 
> 
> Ken,
> 
> It is a potential shock hazard if the coax run is long and runs from
> building to building (for instance) where the ground potentials may be
> different in the different buildings.  One can develop a large potential on
> the shield of the cable, so that if you put yourself between the cable
> shield and ground you may get a strong shock.  That is the reason for
> isolating the shield from more than one direct connection to ground.  It is
> a real issue.  The result for EMI is, as you have noted, the creation of an
> egregious EMI offender.  I have used the chassis mounted BNC connectors with
> built-in capacitors successfully.
> 
> Jim
> 
> 
> Jim Knighten, Ph.D.
> Teradata, a Division of NCR  http://www.ncr.com
> 17095 Via Del Campo
> San Diego, CA 92127
> USA
> Tel: 858-485-2537
> Fax: 858-485-3788
> jim.knigh...@ncr.com
> 
> -Original Message-
> From:  Ken Javor [mailto:ken.ja...@emccompliance.com]
> Sent: Wednesday, March 05, 2003 12:58 PM
> To: Knighten, Jim L; emc-p...@majordomo.ieee.org
> Subject: Re: Ethernet coax connection
> 
> Assume complete ignorance on my part.  What is the safety concern?
> 
> 
> on 3/5/03 3:50 PM, Knighten, Jim L at jk100...@teradata-ncr.com wrote:
> 
>> Ken,
>> 
>> Safety considerations are the reason for the spec requirement.  You are
>> allowed to ground the shield at one point.
>> 
>> Try using a BNC coax connector with a built-in capacitor to ground.  That
>> gives you an AC connection to ground and is often quite effective.  These
>> are off-the-shelf parts.
>> 
>> Jim
>> 
>> 
>> Jim Knighten, Ph.D.
>> Teradata, a Division of NCR  http://www.ncr.com
>> 17095 Via Del Campo
>> San Diego, CA 92127
>> USA
>> Tel: 858-485-2537
>> Fax: 858-485-3788
>> jim.knigh...@ncr.com
>> 
>> -Original Message-
>> From:  Ken Javor [mailto:ken.ja...@emccompliance.com]
>> Sent: Wednesday, March 05, 2003 12:38 PM
>> To: emc-p...@majordomo.ieee.org
>> Subject: Ethernet coax connection
>> 
>> 
>> Question for list members:
>> 
>> Background:  I am troubleshooting a complex integration of military
> hardware
>> and COTS.  One COTS piece of equipment has an RG-58 coaxial connection,
> but
>> the coax connector is an isolated feedthrough bnc.  From a radiated
>> emissions point-of-view, that is hurting us.  One of the engineers here
> said
>> that is part of the spec - Ethernet shields are not supposed to be chassis
>> grounded.
>> 
>> Question:  Can someone please explain the reason for that, and how this is
>> usually handled to minimize radiated emissions?
>> 
>> Thank you.
>> 
>> Ken Javor
>> EMC Compliance
>> Huntsville, Alabama
>> 256/650-5261
>> 
>> 
>> 
>> ---
>> This message is from the IEEE EMC Society Product Safety
>> Technical Committee emc-pstc discussion list.
>> 
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>> 

-- 

Ken Javor
EMC Compliance
Huntsville, Alabama
256/650-5261




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RE: Ethernet coax connection

[Knighten, Jim L]

I knew that I was headed for trouble when I responded to Ken Javor original
question about EMI frustrations with 10Base2 Ethernet.  I figured the safety
guys would pummel me a little - and I accept the comments.  However, I
couldn't resist since I have experienced the same EMI frustrations.

Nevertheless, good EMI engineers are sometimes faced with an existing design
that uses 10Base2 (legacy, if you will) and has the severe EMI problem that
an experienced EMI engineer could anticipate.  Ignoring it is unacceptable
>from a regulatory point of view (in the case of commercial products), or
>from other spec and/or contract reasons in the government world.  Many, if
not most of the practical solutions appear to violate either the letter or
the spirit of the Ethernet 10Base2 spec.  This puts the EMI engineer in the
same seemingly untenable spot that Ken Javor appeared to be in yesterday.
I've been there and I empathize.  

Jim


Jim Knighten, Ph.D.
Teradata, a Division of NCR http://www.ncr.com
17095 Via Del Campo
San Diego, CA 92127
USA
Tel: 858-485-2537
Fax: 858-485-3788
jim.knigh...@ncr.com

 -Original Message-
From:   Robert Johnson [mailto:john...@itesafety.com] 
Sent:   Wednesday, March 05, 2003 9:53 PM
To: Knighten, Jim L
Cc: emc-p...@majordomo.ieee.org
Subject:RE: Ethernet coax connection

 << File: Robert Johnson.vcf >> If you have shock level differences between
the grounds in two different
buildings, either an entire building isn't connected to an earth electrode,
or someone is paying a whopping electric bill to heat up mother earth. I
suspect the shock situation you were talking about was a power cross
condition, either to the cable or within equipment. I hope it was diagnosed
and fixed.

The voltage differences between two buildings are generally very low, on the
order of a couple volts, but due to fractional ohm impedances are capable of
very high currents. Building maintenance procedures should routinely be
checking for ground currents since they indicate faults in the power system.

Note that in accordance with IEC 62102, 10base2 is an SELV circuit and
should not be used for exposed plant (between building) wiring. Ethernet
distance specs and application recommendations also go against exposed plant
wiring. Ethernet 10base5 is considered a TNV-1 circuit and suitable for
exposed plant use, is insulated and requires single point grounding. Optical
fiber is a better recent development and the best answer for exposed plant
lines these days.

Note that IEC 62102 provides an extensive list of interconnect circuit types
and what category they fit into with regard to shock level (SELV, TNV,
hazardous, etc). It's an important reference for any engineer designing
interconnect circuits in determining isolation needs.


Bob Johnson
ITE Safety
 


From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Knighten, Jim L
Sent: Wednesday, March 05, 2003 7:51 PM
To: Rich Nute
Cc: ken.ja...@emccompliance.com; emc-p...@majordomo.ieee.org
Subject: RE: Ethernet coax connection


Rich,

I think you must be correct.  I do have anecdotal evidence of persons being
"knocked on their butts" by grabbing hold of an Ethernet coax in a large
facility and trying to connect it to a computer.

My experience is in EMC and the 10Base2 Ethernet (coax) is a persistent
offender.  (Actually, the twisted pair stuff has its own set of EMC
problems.)

Regards,

Jim


Jim Knighten, Ph.D.
Teradata, a Division of NCR http://www.ncr.com
17095 Via Del Campo
San Diego, CA 92127
USA
Tel: 858-485-2537
Fax: 858-485-3788
jim.knigh...@ncr.com

 -Original Message-
From:   Rich Nute [mailto:ri...@sdd.hp.com] 
Sent:   Wednesday, March 05, 2003 4:31 PM
To: Knighten, Jim L
Cc: ken.ja...@emccompliance.com; emc-p...@majordomo.ieee.org
Subject:Re: Ethernet coax connection




Hi Jim:

>   It is a potential shock hazard if the coax run is long and runs from
>   building to building (for instance) where the ground potentials may be
>   different in the different buildings.  One can develop a large potential
on
>   the shield of the cable, so that if you put yourself between the cable
>   shield and ground you may get a strong shock.  That is the reason for
>   isolating the shield from more than one direct connection to ground.  It
is
>   a real issue.  

I don't believe the issue is that of electric shock.  I don't believe the
current and resistance of the neutral are high enough to develop 30 volts
(the shock hazard limit).
Instead, I believe the problem is that, with two connections, the shield is
in parallel with the neutral.  That means that some of the neutral current
will pass through the shield, and will likely open a PWB trace somewhere.
In the process, the PWB trace heating may start a fire.
I believe the circuit is:
(You may not be able to read this schematic if your mail reader is not set
for plain ASCII text.)


L  

International symbol for rf comminication link condition for use on Medical device

[Brodie Pedersen]

Hi all, 
I am looking for an internationally recognized reception indicator of
the condition of an RF link between a sensor and a display type module.
I have IEC 60417 and am not finding anything that seems to look right or
make sense for the application, was wondering if there is a symbol
indicated in ISO 7000 or other symbol standard I am not aware of, that
might be appropriate.  I would like to avoid buying expensive
unnecessary standards unless I know there is an item of relevance in it.
Thank you for your help and support in advance.

Brodie Pedersen
Nonin Medical Inc.
Plymouth MN


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RE: E26/E27 Lamp-Base

[James, Chris]

This is a multi-part message in MIME format.
Check out: http://www.acclaiminternatio
al.com/AudioVisual/products/lamps/sldlampbases.htm

E26 is US style
E27 is European standard Edison screw


 
 E26    E27
  
Medium Skirted
(E26)ES
Edison Screw
(E27)   
 


Regards,

Chris
___
Chris James
Engineering Services Manager
Dolby Laboratories, Inc. (UK)

Direct: 01793 842136




From: Carl [ mailto:c...@baclcorp.com]
Sent: 05 March 2003 22:51
To: emc-p...@majordomo.ieee.org
Subject: E26/E27 Lamp-Base



Hi,

Does anybody know the differences between E26 and E27(lamp base)? Thanks.

Regards,

Carl Yi



This message is from the IEEE EMC Society Product Safety Technical Committee
emc-pstc discussion list.

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This message (including any attachments) may contain confidential information
intended for a specific individual and purpose. If you are not the intended
recipient, delete this message. If you are not the intended recipient,
disclosing, copying, distributing, or taking any action based on this message
is strictly prohibited.



Title: Message



Check out: http://www.acclaiminternational.com/AudioVisual/products/lamps/sldlampbases.htmE26 
is US styleE27 is European standard Edison screw
 


  
  





  
Medium Skirted(E26)
ESEdison 
  Screw(E27)
 
Regards,Chris___Chris 
JamesEngineering 
Services ManagerDolby Laboratories, Inc. (UK)Direct: 01793 
842136-Original Message-From: Carl [mailto:c...@baclcorp.com]Sent: 05 March 
2003 22:51To: emc-p...@majordomo.ieee.orgSubject: E26/E27 
Lamp-BaseHi,Does anybody know the differences between 
E26 and E27(lamp base)? Thanks.Regards,Carl 
Yi---This message is 
>from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion 
list.Visit our web site at:  http://www.ewh.ieee.org/soc/emcs/pstc/To 
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davehe...@attbi.comFor policy questions, send mail 
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Nute:   
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Bacher: 
j.bac...@ieee.orgArchive is being moved, we will announce when it is 
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This message (including any attachments) may contain confidential information intended for a specific individual and purpose. If you are not the intended recipient, delete this message. If you are not the intended recipient, disclosing, copying, distributing, or taking any action based on this message is strictly prohibited.

<>
<>

Re: Ethernet coax connection

[John Woodgate]

I read in !emc-pstc that Knighten, Jim L 
wrote (in <61A60D883863D411A36600D0B785B50C0D8C6EC0@susdayte51.daytonoh.
ncr.com>) about 'Ethernet coax connection' on Wed, 5 Mar 2003:
>One can develop a large potential on
>the shield of the cable, so that if you put yourself between the cable
>shield and ground you may get a strong shock. 

If there is enough voltage to give a 'strong shock', there is far more
than enough to pass shield current sufficient to burn the cable up.
Ground potential differences are typically sources with milliohm
internal impedances.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk 
Interested in professional sound reinforcement and distribution? Then go to 
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!


This message is from the IEEE EMC Society Product Safety
Technical Committee emc-pstc discussion list.

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RE: Ethernet coax connection

[Robert Johnson]

This is a multi-part message in MIME format.
If you have shock level differences between the grounds in two different
buildings, either an entire building isn't connected to an earth electrode,
or someone is paying a whopping electric bill to heat up mother earth. I
suspect the shock situation you were talking about was a power cross
condition, either to the cable or within equipment. I hope it was diagnosed
and fixed.

The voltage differences between two buildings are generally very low, on the
order of a couple volts, but due to fractional ohm impedances are capable of
very high currents. Building maintenance procedures should routinely be
checking for ground currents since they indicate faults in the power system.

Note that in accordance with IEC 62102, 10base2 is an SELV circuit and
should not be used for exposed plant (between building) wiring. Ethernet
distance specs and application recommendations also go against exposed plant
wiring. Ethernet 10base5 is considered a TNV-1 circuit and suitable for
exposed plant use, is insulated and requires single point grounding. Optical
fiber is a better recent development and the best answer for exposed plant
lines these days.

Note that IEC 62102 provides an extensive list of interconnect circuit types
and what category they fit into with regard to shock level (SELV, TNV,
hazardous, etc). It's an important reference for any engineer designing
interconnect circuits in determining isolation needs.


Bob Johnson
ITE Safety
 


From: owner-emc-p...@majordomo.ieee.org
[mailto:owner-emc-p...@majordomo.ieee.org] On Behalf Of Knighten, Jim L
Sent: Wednesday, March 05, 2003 7:51 PM
To: Rich Nute
Cc: ken.ja...@emccompliance.com; emc-p...@majordomo.ieee.org
Subject: RE: Ethernet coax connection


Rich,

I think you must be correct.  I do have anecdotal evidence of persons being
"knocked on their butts" by grabbing hold of an Ethernet coax in a large
facility and trying to connect it to a computer.

My experience is in EMC and the 10Base2 Ethernet (coax) is a persistent
offender.  (Actually, the twisted pair stuff has its own set of EMC
problems.)

Regards,

Jim


Jim Knighten, Ph.D.
Teradata, a Division of NCR http://www.ncr.com
17095 Via Del Campo
San Diego, CA 92127
USA
Tel: 858-485-2537
Fax: 858-485-3788
jim.knigh...@ncr.com

 -Original Message-
From:   Rich Nute [mailto:ri...@sdd.hp.com] 
Sent:   Wednesday, March 05, 2003 4:31 PM
To: Knighten, Jim L
Cc: ken.ja...@emccompliance.com; emc-p...@majordomo.ieee.org
Subject:Re: Ethernet coax connection




Hi Jim:

>   It is a potential shock hazard if the coax run is long and runs from
>   building to building (for instance) where the ground potentials may be
>   different in the different buildings.  One can develop a large potential
on
>   the shield of the cable, so that if you put yourself between the cable
>   shield and ground you may get a strong shock.  That is the reason for
>   isolating the shield from more than one direct connection to ground.  It
is
>   a real issue.  

I don't believe the issue is that of electric shock.  I don't believe the
current and resistance of the neutral are high enough to develop 30 volts
(the shock hazard limit).
Instead, I believe the problem is that, with two connections, the shield is
in parallel with the neutral.  That means that some of the neutral current
will pass through the shield, and will likely open a PWB trace somewhere.
In the process, the PWB trace heating may start a fire.
I believe the circuit is:
(You may not be able to read this schematic if your mail reader is not set
for plain ASCII text.)


L  Bldg A
 +-++
 | ||
 | ||
 | |   | |
(~) 120 V  |   | | load
 | |   | |
 | ||
 |N||
 +-++-+-+
 |utility  |   || Bldg A  |
 |ground   |   || ground  |
 |rod  |   || rod |PE   BNC shield
   -   |   |  -   +->>---+
---|   |   ---   |
 - |   |-|
   |   | |
   |   | |
   |   | |
   |   | L   Bldg B  |
   ++|
   |||
   |||
   |   | |   |
   |   | | load  |
   |   | |   |
   ||