Re: [PSES] Woodgate's reply on residential Immunity field strength

[Brian Kunde]

The exposure limits according to the ICNIRP depends on frequency, of course.

>From 1hz to 300hz the Occupational limits are like 20kV/m for E-Field and
40k to 200uT.

>From 3khz to 10Mhz the limit is 170V/m (100uT).  For the General Public (up
to 24 hours a day), the limit is 83V/m (27uT).

For example.

The Other Brian

On Thu, Jul 27, 2023 at 3:48 PM John Woodgate  wrote:

> The EM field exposure limits are not always in standards: in Europe they
> are in a European Council document based on Commission-funded research
> (ICNIRP). I don't recall any limits as low as 10 V/m.
> On 2023-07-27 19:07, Richard Nute wrote:
>
>
>
> I’m a product safety engineer.  This discussion is based upon a safety
> standard specifying a limit for the accessible electric field strength.
>
>
>
> Doug Smith said:
>
>
>
> “These days we think 10 V/m is dangerous.“
>
> See:
>
>
>
> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553569/
>
>
>
> This article (with scholarly research annotated) essentially says that we
> don’t know the effects of electric and magnetic fields on the body.  It
> cites 0.4 uT (>100 V/m) as a potential limit for children.  Doug goes on to
> cite his experience with exposure to 100 times 100 V/m with no ill
> effects.
>
>
>
> I wonder how the standards writers came up with limiting field strength
> when there is no definitive bodily injury?  Probably BOGSAT.
>
>
>
> Best regards,
>
> Rich
>
>
>
> ps:  Field strength conversion calculator:
>
>
>
> https://www.compeng.com.au/field-strength-calculator/
>
>
>
>
> --
>
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> emc-pstc postings are archived and searchable on the web at:
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Re: [PSES] Woodgate's reply on residential Immunity field strength

[John Woodgate]

The EM field exposure limits are not always in standards: in Europe they 
are in a European Council document based on Commission-funded research 
(ICNIRP). I don't recall any limits as low as 10 V/m.


On 2023-07-27 19:07, Richard Nute wrote:


I’m a product safety engineer.  This discussion is based upon a safety 
standard specifying a limit for the accessible electric field strength.


Doug Smith said:

“These days we think 10 V/m is dangerous.“

See:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553569/

This article (with scholarly research annotated) essentially says that 
we don’t know the effects of electric and magnetic fields on the 
body.  It cites 0.4 uT (>100 V/m) as a potential limit for children.  
Doug goes on to cite his experience with exposure to 100 times 100 V/m 
with no ill effects.


I wonder how the standards writers came up with limiting field 
strength when there is no definitive bodily injury? Probably BOGSAT.


Best regards,

Rich

ps: Field strength conversion calculator:

https://www.compeng.com.au/field-strength-calculator/



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Re: [PSES] Woodgate's reply on residential Immunity field strength

[Ken Javor]

Some thirty years ago, the keynote speaker at an IEEE EMC symposium in the USA 
was a noted medical researcher working on the long term health effects of 
exposure to EM fields (neurological as opposed to simply thermal effects).

 

In substance, what he said was we evolved to live with certain levels of EM 
field exposure (obviously a few hundred thousand years before Hertz and 
Marconi).  He went on to say that you couldn’t hide in a shield room, either, 
on account of we evolved in a non-zero EM field environment, so no EM fields 
was also not good.

 

When I hear things like this – another example being a paleo diet – I am struck 
by the fact that what we evolved to be was a being that was old at age 35. 
Neanderthals were not the monsters their discoverer’s pieced together – they 
were all crippled up with arthritis and/or rheumatism sleeping on the ground or 
in cold caves.

 

You can live a fairly unhealthy lifestyle and still make it to age 35 – barring 
catastrophic injury or illness, the warranty is in effect. After that, it does 
depend on personal habits, genes and the environment, but the idea that how we 
evolved has much effect on life past 35 seems a bit of a stretch.

 

I am reminded of one of those old velvet paintings/posters you’d find at garage 
sales and flea markets. Some old cowboy, a lot the worse for wear, missing some 
teeth and so on, with the caption, “If I’d known I was going to live this long, 
I’d taken better care of myself.”

 

-- 

Ken Javor

(256) 650-5261

 

From: Richard Nute 
Reply-To: 
Date: Thursday, July 27, 2023 at 1:07 PM
To: 
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength

 

 

I’m a product safety engineer.  This discussion is based upon a safety standard 
specifying a limit for the accessible electric field strength.

 

Doug Smith said:  

 

“These days we think 10 V/m is dangerous.“

See:

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553569/

 

This article (with scholarly research annotated) essentially says that we don’t 
know the effects of electric and magnetic fields on the body.  It cites 0.4 uT 
(>100 V/m) as a potential limit for children.  Doug goes on to cite his 
experience with exposure to 100 times 100 V/m with no ill effects.  

 

I wonder how the standards writers came up with limiting field strength when 
there is no definitive bodily injury?  Probably BOGSAT.   

 

Best regards,

Rich

 

ps:  Field strength conversion calculator:

 

https://www.compeng.com.au/field-strength-calculator/

 

 

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Re: [PSES] Woodgate's reply on residential Immunity field strength

[Richard Nute]

 

I'm a product safety engineer.  This discussion is based upon a safety
standard specifying a limit for the accessible electric field strength.

 

Doug Smith said:  

 

"These days we think 10 V/m is dangerous."

See:

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553569/

 

This article (with scholarly research annotated) essentially says that we
don't know the effects of electric and magnetic fields on the body.  It
cites 0.4 uT (>100 V/m) as a potential limit for children.  Doug goes on to
cite his experience with exposure to 100 times 100 V/m with no ill effects.


 

I wonder how the standards writers came up with limiting field strength when
there is no definitive bodily injury?  Probably BOGSAT.   

 

Best regards,

Rich

 

ps:  Field strength conversion calculator:

 

https://www.compeng.com.au/field-strength-calculator/

 

 


-

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Re: [PSES] Woodgate's reply on residential Immunity field strength

[Ken Javor]

I don’t see 100 V/m. Assuming an omni pattern, 0.5 W peak power and using, 

 

E = √(30•ERP) / r

 

the phone would need to be within a few centimeters of the observation point, 
and in that close the distance scaling assumption in that equation breaks down.

 

-- 

Ken Javor

(256) 650-5261

 

From: "doug emcesd.com" 
Reply-To: "doug emcesd.com" 
Date: Tuesday, July 25, 2023 at 6:53 PM
To: 
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength

 

Hi All,

 

My observation is that a cell phone at max power, close to the product, 
generates voltages and currents in the product that are on the order of what a 
100 V/m far field would induce!

 

I have seen many manifestations of this including making a product permanently 
non-functional. Interestingly enough, the design feature within that product 
that caused the issue was ground fill on a circuit board that was resonant in 
the upper cell phone band. Pretty easy to find with signal injection into the 
structure.

 

These kind of problems are easily found using a coaxial dipole. Here are a few 
links:

 

https://emcesd.com/tt2006/tt020106.htm

 

https://emcesd.com/tt2010/tt080410.htm

 

As with ESD, using the standards based test setup for troubleshooting these 
kind of problems is very inefficient. Once a problem occurs, I build a custom 
way of injecting signals, like the above, and find the problem very quickly. In 
this case, one just needs a signal source of appropriate power and the coaxial 
dipole.

 

An interesting bit of my history. These days we think 10 V/m is dangerous. But 
when I was 15, I played for hours at a time with a device I made that generated 
a continuous signal at 300 kHz of 10,000-20,000 V/m and I am still here! I was 
developing 600 Watts of power from a pair of 811A power triodes oscillating at 
300 kHz to feed the resonant Tesla coil structure I built. The effects were 
pretty amazing, lighting up fluorescent tubes 4-6 feet away to full brilliance 
with no wires and even incandescent bulbs would light in the vicinity, held in 
my hand! Pieces of metal nearby got hot from induction heating.

 

I did lots of crazy technical things when I was 12-18 years of age. By the way, 
those 811A tubes above (the “A” versions had cooling fins on the plates) were 
powered from a 3B28 xenon gas rectifier tube and had 1500 V and at more than 
half an Ampere available on the plate caps. Enough to kill one rather quickly, 
but I knew what I was doing back then and survived to write this.

 

Doug

From: Charlie Blackham  
Sent: Tuesday, July 25, 2023 0:06
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength

 

The residential level of 3m V/m was in IEC 1000-4-3 predates portable phones, 
WiFi, Bluetooth and all the other mobile and portable transmitters widely in 
use today.

 

The 20+ V/m field strengths in these standards are what is obtained from a 
cellular phone at maximum power, or WiFi device, at approximately 0.3 m / 1 ft.

 

Now, on live networks the 99% percentile transmit power of a cell phone is 
around 1% of maximum power, but that’s not considered in safety standards such 
as SAR testing

 

Best regards

Charlie

 

Charlie Blackham

Sulis Consultants Ltd

Tel: +44 (0)7946 624317

Web: https://sulisconsultants.com/ 

Registered in England and Wales, number 05466247

 

From: Brian Gregory  
Sent: Monday, July 24, 2023 10:49 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength

 

 

The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not a 
medical standard, but Annex A does call out the medical standard 60601-1-2 as a 
reference, as well as CENELEC 50204.  We can't figure out why;  cell phones 
produce less than half that, and our WiFi transmitter is probably 
representative, and is rated well under 1 W.  I could see a higher immunity 
standard as needed for commercial environments, say in a bank of 4-5 chargers.

 

Following along in 61000-4-3, we agree with John that residential applications 
are clearly best matched to the definition for Class 2 environment, and the 
table in Clause 5 says the limits for Class 2 equipment is 3 V/m.  20 V/m does 
not show up in Clause 5 of 61000-4-3 for any class.  

 

So, I've should to reach out to a UL standards group and find out if this is 
really necessary for residential applications.   Our local lab can't do more 
than 10, and an overseas affiliated lab is similarly limited.  I'd like to know 
were this requirement comes from.   This is more a question for EV Charging 
safety than a mainstream EMC question. 

 

As a backup, I could request a comment to Ken's point is if they define the 
peak of the modulation as 20 V/m.  I don't know where these are defined.

 

Thanks for all the detailed replies!

 

Colorado Brian 
720-450-4933



-- Original M

Re: [PSES] Woodgate's reply on residential Immunity field strength

[doug emcesd.com]

Hi All,

My observation is that a cell phone at max power, close to the product, 
generates voltages and currents in the product that are on the order of what a 
100 V/m far field would induce!

I have seen many manifestations of this including making a product permanently 
non-functional. Interestingly enough, the design feature within that product 
that caused the issue was ground fill on a circuit board that was resonant in 
the upper cell phone band. Pretty easy to find with signal injection into the 
structure.

These kind of problems are easily found using a coaxial dipole. Here are a few 
links:

https://emcesd.com/tt2006/tt020106.htm

https://emcesd.com/tt2010/tt080410.htm

As with ESD, using the standards based test setup for troubleshooting these 
kind of problems is very inefficient. Once a problem occurs, I build a custom 
way of injecting signals, like the above, and find the problem very quickly. In 
this case, one just needs a signal source of appropriate power and the coaxial 
dipole.

An interesting bit of my history. These days we think 10 V/m is dangerous. But 
when I was 15, I played for hours at a time with a device I made that generated 
a continuous signal at 300 kHz of 10,000-20,000 V/m and I am still here! I was 
developing 600 Watts of power from a pair of 811A power triodes oscillating at 
300 kHz to feed the resonant Tesla coil structure I built. The effects were 
pretty amazing, lighting up fluorescent tubes 4-6 feet away to full brilliance 
with no wires and even incandescent bulbs would light in the vicinity, held in 
my hand! Pieces of metal nearby got hot from induction heating.

I did lots of crazy technical things when I was 12-18 years of age. By the way, 
those 811A tubes above (the "A" versions had cooling fins on the plates) were 
powered from a 3B28 xenon gas rectifier tube and had 1500 V and at more than 
half an Ampere available on the plate caps. Enough to kill one rather quickly, 
but I knew what I was doing back then and survived to write this.

Doug
[https://lh4.googleusercontent.com/_HuR3Ky2TF_XhFHyxnYRmiq7nHQldnMsPNYFaLG6kb5T4y8MeCe-BDC_BscJtSFgszSSjssihHS-pjM3-jwNP8S0CwE-gN8fsRsPkojiAlmpBwb20vIVizS-siCUywW_jqrefbVr]
From: Charlie Blackham 
Sent: Tuesday, July 25, 2023 0:06
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength

The residential level of 3m V/m was in IEC 1000-4-3 predates portable phones, 
WiFi, Bluetooth and all the other mobile and portable transmitters widely in 
use today.

The 20+ V/m field strengths in these standards are what is obtained from a 
cellular phone at maximum power, or WiFi device, at approximately 0.3 m / 1 ft.

Now, on live networks the 99% percentile transmit power of a cell phone is 
around 1% of maximum power, but that's not considered in safety standards such 
as SAR testing

Best regards
Charlie

Charlie Blackham
Sulis Consultants Ltd
Tel: +44 (0)7946 624317
Web: 
https://sulisconsultants.com/<https://urldefense.proofpoint.com/v2/url?u=https-3A__sulisconsultants.com_&d=DwMFAg&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=c9NR2mGfldry-2pM9Bbuww&m=wj5sNmgwgR_ZaeiylApyxkaL3lAz5hfciU1k-Q7qKo_w6zUvVL78huPr0ln5Bt_y&s=zMRqUtXLpZFb8clC7VkPNo2yZvCxVnLMAWMcnUFr7zY&e=>
Registered in England and Wales, number 05466247

From: Brian Gregory 
mailto:brian_greg...@netzero.net>>
Sent: Monday, July 24, 2023 10:49 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG<mailto:EMC-PSTC@LISTSERV.IEEE.ORG>
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength


The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not a 
medical standard, but Annex A does call out the medical standard 60601-1-2 as a 
reference, as well as CENELEC 50204.  We can't figure out why;  cell phones 
produce less than half that, and our WiFi transmitter is probably 
representative, and is rated well under 1 W.  I could see a higher immunity 
standard as needed for commercial environments, say in a bank of 4-5 chargers.

Following along in 61000-4-3, we agree with John that residential applications 
are clearly best matched to the definition for Class 2 environment, and the 
table in Clause 5 says the limits for Class 2 equipment is 3 V/m.  20 V/m does 
not show up in Clause 5 of 61000-4-3 for any class.

So, I've should to reach out to a UL standards group and find out if this is 
really necessary for residential applications.   Our local lab can't do more 
than 10, and an overseas affiliated lab is similarly limited.  I'd like to know 
were this requirement comes from.   This is more a question for EV Charging 
safety than a mainstream EMC question.

As a backup, I could request a comment to Ken's point is if they define the 
peak of the modulation as 20 V/m.  I don't know where these are defined.

Thanks for all the detailed replies!

Colorado Brian
720-450-4933


-- Original Mes

Re: [PSES] Woodgate's reply on residential Immunity field strength

[Charlie Blackham]

The residential level of 3m V/m was in IEC 1000-4-3 predates portable phones, 
WiFi, Bluetooth and all the other mobile and portable transmitters widely in 
use today.

The 20+ V/m field strengths in these standards are what is obtained from a 
cellular phone at maximum power, or WiFi device, at approximately 0.3 m / 1 ft.

Now, on live networks the 99% percentile transmit power of a cell phone is 
around 1% of maximum power, but that's not considered in safety standards such 
as SAR testing

Best regards
Charlie

Charlie Blackham
Sulis Consultants Ltd
Tel: +44 (0)7946 624317
Web: https://sulisconsultants.com/
Registered in England and Wales, number 05466247

From: Brian Gregory 
Sent: Monday, July 24, 2023 10:49 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength


The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not a 
medical standard, but Annex A does call out the medical standard 60601-1-2 as a 
reference, as well as CENELEC 50204.  We can't figure out why;  cell phones 
produce less than half that, and our WiFi transmitter is probably 
representative, and is rated well under 1 W.  I could see a higher immunity 
standard as needed for commercial environments, say in a bank of 4-5 chargers.

Following along in 61000-4-3, we agree with John that residential applications 
are clearly best matched to the definition for Class 2 environment, and the 
table in Clause 5 says the limits for Class 2 equipment is 3 V/m.  20 V/m does 
not show up in Clause 5 of 61000-4-3 for any class.

So, I've should to reach out to a UL standards group and find out if this is 
really necessary for residential applications.   Our local lab can't do more 
than 10, and an overseas affiliated lab is similarly limited.  I'd like to know 
were this requirement comes from.   This is more a question for EV Charging 
safety than a mainstream EMC question.

As a backup, I could request a comment to Ken's point is if they define the 
peak of the modulation as 20 V/m.  I don't know where these are defined.

Thanks for all the detailed replies!

Colorado Brian
720-450-4933


-- Original Message --
From: John Woodgate mailto:j...@woodjohn.uk>>
To: Brian Gregory mailto:brian_greg...@netzero.net>>
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100

61000-4-3 is a Basic Standard. It does not specify test levels but indicates 
possible test levels. You need to look in detail at Clause 5, but look at these 
words:

 Product committees shall select the appropriate test level for each frequency 
range needing to be tested as well as the frequency ranges.

The residential environment is usually designated Class 2 (see Annex E of the 
standard), which calls for 3 V/m.
==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk<http://www.woodjohn.uk>
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi (340 
- 245 BC)
On 2023-07-21 17:44, Brian Gregory wrote:
 Hello colleagues,

We are building EV Chargers for residential markets (not just US) and one of 
the safety applicable standards is UL 2231-2.  It calls out  IEC 61000-4-3 for 
immunity testing parameters, which states a requirement for a field strength of 
20V/m.  Our EMC expert says typically testing is "done at 3 Vrms, which is 
standard for most products in residential environments."   He can only test up 
to 10V, and we're hearing the same from an overseas lab to whom our 
manufacturer refers.

Does FCC Part B have guidelines for field strength we can cite?   Can some 
offer this "DC guy" (aka, 60 Hz) a quick definition of what the 20V/m 
represents?

I'm guessing 20 V/m is for higher density commercial applications, aka charging 
stations, so we probably need an exception for residential.

Thank you!

Colorado Brian
720-450-4933


This message is from the IEEE Product Safety Engineering Society emc-pstc 
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To u

Re: [PSES] Woodgate's reply on residential Immunity field strength

[James Pawson (U3C)]

Hi Brian,

 

In IEC 61000-4-3 the level is defined as the unmodulated rms field strength.
The modulation (1kHz 80% AM) is applied symmetrically around that level.
>From memory this means that the peak is 5.1dB higher than the level.

 

The opposite is true in ISO 11452-2 for automotive where the level is the
maximum peak and the modulation (AM, same as above) is modulated down from
this peak.

 

All the best

James

 

James Pawson

Managing Director & EMC Problem Solver

 

Unit 3 Compliance Ltd

EMC : Environmental & Vibration : Electrical Safety : CE & UKCA :
Consultancy

 

 <http://www.unit3compliance.co.uk/> www.unit3compliance.co.uk |
<mailto:ja...@unit3compliance.co.uk> ja...@unit3compliance.co.uk 

+44(0)1274 911747  |  +44(0)7811 139957

2 Wellington Business Park, New Lane, Bradford, BD4 8AL

Registered in England and Wales # 10574298

 

Office hours:

Every morning my full attention is on consultancy, testing, and
troubleshooting activities for our customers' projects. I'm contactable
between 1300h to 1730h from Monday to Friday.

For inquiries, bookings, and testing updates please send us an email on
he...@unit3compliance.co.uk <mailto:he...@unit3compliance.co.uk>  or call
01274 911747. Our lead times for testing and consultancy are typically 4-5
weeks.

 

 

 

 

From: Brian Gregory  
Sent: Monday, July 24, 2023 10:49 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength

 

 

The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not a
medical standard, but Annex A does call out the medical standard 60601-1-2
as a reference, as well as CENELEC 50204.  We can't figure out why;  cell
phones produce less than half that, and our WiFi transmitter is probably
representative, and is rated well under 1 W.  I could see a higher immunity
standard as needed for commercial environments, say in a bank of 4-5
chargers.

 

Following along in 61000-4-3, we agree with John that residential
applications are clearly best matched to the definition for Class 2
environment, and the table in Clause 5 says the limits for Class 2 equipment
is 3 V/m.  20 V/m does not show up in Clause 5 of 61000-4-3 for any class.  

 

So, I've should to reach out to a UL standards group and find out if this is
really necessary for residential applications.   Our local lab can't do more
than 10, and an overseas affiliated lab is similarly limited.  I'd like to
know were this requirement comes from.   This is more a question for EV
Charging safety than a mainstream EMC question. 

 

As a backup, I could request a comment to Ken's point is if they define the
peak of the modulation as 20 V/m.  I don't know where these are defined.

 

Thanks for all the detailed replies!

 

Colorado Brian 
720-450-4933



-- Original Message --
From: John Woodgate mailto:j...@woodjohn.uk> >
To: Brian Gregory mailto:brian_greg...@netzero.net> >
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100

61000-4-3 is a Basic Standard. It does not specify test levels but indicates
possible test levels. You need to look in detail at Clause 5, but look at
these words:

 Product committees shall select the appropriate test level for each
frequency range needing to be tested as well as the frequency ranges.

The residential environment is usually designated Class 2 (see Annex E of
the standard), which calls for 3 V/m.


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk <http://www.woodjohn.uk> 
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi
(340 - 245 BC)

On 2023-07-21 17:44, Brian Gregory wrote:

 Hello colleagues, 

 

We are building EV Chargers for residential markets (not just US) and one of
the safety applicable standards is UL 2231-2.  It calls out  IEC 61000-4-3
for immunity testing parameters, which states a requirement for a field
strength of 20V/m.  Our EMC expert says typically testing is "done at 3
Vrms, which is standard for most products in residential environments."   He
can only test up to 10V, and we're hearing the same from an overseas lab to
whom our manufacturer refers.  

 

Does FCC Part B have guidelines for field strength we can cite?   Can some
offer this "DC guy" (aka, 60 Hz) a quick definition of what the 20V/m
represents?

 

I'm guessing 20 V/m is for higher density commercial applications, aka
charging stations, so we probably need an exception for residential.  

 

Thank you!

 

Colorado Brian 
720-450-4933

  _  

This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
mailto:emc-p...@ieee.org> > All em

Re: [PSES] Woodgate's reply on residential Immunity field strength

[Jim Bacher, WB8VSU]

Yes. The standards need to allow for possibilities.

I have about a 3 dB gain antenna that is about a meter away from the 
charger port. It transmits about 15 watts at 144.39 MHz to send out an APRS 
position packet.  I recently bought a PHEV, although my 2 minute timer is 
not yet installed, but it will be.



The catch is I am not the only one doing this and who knows what the others 
have for antenna to charger spacing, etc. Although most of the Hams likely 
do not have EVs at the moment, but some do.



Bob Bruninga WB4APR, who was the ham behind the creation of APRS drove a 
Prius. He passed away a few years ago. Info on APRS is at: http://www.aprs.org/



I could easily be on a handheld device and talking with someone when 
plugging or unplugging the charger cable. I had a issue many years ago 
where the hand held transceiver exposed a device to 45 V/m (someone else 
did the calculations).



I had friends that in the late 1970s were remotely controlling transceivers 
in their cars. Cars at that time obviously were not EVs. They would use it 
at work. They owned the businesses, so they could play if they wanted to. 
The thing is others could be doing the same today, while the car is 
charging. Plus like I mentioned highway patrol cars use the same setup. If 
they start using EVs, they also would be a similar issue.



Plus what if a car with a high powered transceiver parks near by?

Jim

On July 24, 2023 6:17:45 PM John Woodgate  wrote:

While the vehicle is on charge or vey near a charger?
On 2023-07-24 23:12, Jim Bacher, WB8VSU wrote:
John, I have transmitter that transmits on a VHF Frequency about 2 minutes 
after I shut the car off. A number of setups allow a person to use a hand 
held device to access a higher powered transceiver that is in the car. It's 
fairly common setup for highway patrol vehicles, due to distance from the 
control points.


Jim



On July 24, 2023 6:04:13 PM John Woodgate  wrote:
There are, but 20 V/m still is a very high value. One wouldn't expect a 
transmitter to be used in a car while it is on charge.

On 2023-07-24 22:57, Jim Bacher, WB8VSU wrote:
Wi-Fi and cell phones are not the only transmitters near cars. There are 
police, fire and ham radio transceivers in cars. Some of which are on gain 
antennas and can be remotely accessed to transmit. Not to mention hand held 
transceivers that might walk by.


Jim, WB8VSU


On July 24, 2023 5:51:27 PM Brian Gregory  wrote:


The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not 
a medical standard, but Annex A does call out the medical standard 
60601-1-2 as a reference, as well as CENELEC 50204.  We can't figure out 
why;  cell phones produce less than half that, and our WiFi transmitter is 
probably representative, and is rated well under 1 W.  I could see a higher 
immunity standard as needed for commercial environments, say in a bank of 
4-5 chargers.


Following along in 61000-4-3, we agree with John that residential 
applications are clearly best matched to the definition for Class 2 
environment, and the table in Clause 5 says the limits for Class 2 
equipment is 3 V/m.  20 V/m does not show up in Clause 5 of 61000-4-3 for 
any class.


So, I've should to reach out to a UL standards group and find out if this 
is really necessary for residential applications.   Our local lab can't do 
more than 10, and an overseas affiliated lab is similarly limited.  I'd 
like to know were this requirement comes from.   This is more a question 
for EV Charging safety than a mainstream EMC question.


As a backup, I could request a comment to Ken's point is if they define the 
peak of the modulation as 20 V/m.  I don't know where these are defined.


Thanks for all the detailed replies!

Colorado Brian
720-450-4933

-- Original Message --
From: John Woodgate 
To: Brian Gregory 
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100

61000-4-3 is a Basic Standard. It does not specify test levels but 
indicates possible test levels. You need to look in detail at Clause 5, but 
look at these words:
Product committees shall select the appropriate test level for each 
frequency range needing to be tested as well as the frequency ranges.
The residential environment is usually designated Class 2 (see Annex E of 
the standard), which calls for 3 V/m.

==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi 
(340 - 245 BC)On 2023-07-21 17:44, Brian Gregory wrote:

Hello colleagues,

We are building EV Chargers for residential markets (not just US) and one 
of the safety applicable standards is UL 2231-2.  It calls out  IEC 
61000-4-3 for immunity testing parameters, which states a requirement for a 
field strength of 20V/m.  Our EMC expert says typically testing is 

Re: [PSES] Woodgate's reply on residential Immunity field strength

[Ken Javor]

Piling on, while one may compute very high field intensities from say a mobile 
phone or other such microwave handheld transmitter, these field intensities 
will not illuminate a 1.5 m square area at such levels.  If such levels are in 
fact justified, it might make sense to reduce the required uniform field area, 
thereby allowing the use of higher gain antennas, and lower power amplifier 
requirements at the higher frequencies where such power becomes (even more) 
expensive.

 

-- 

Ken Javor

(256) 650-5261

 

From: John Woodgate 
Reply-To: John Woodgate 
Date: Monday, July 24, 2023 at 5:03 PM
To: 
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength

 

There are, but 20 V/m still is a very high value. One wouldn't expect a 
transmitter to be used in a car while it is on charge.

On 2023-07-24 22:57, Jim Bacher, WB8VSU wrote:

Wi-Fi and cell phones are not the only transmitters near cars. There are 
police, fire and ham radio transceivers in cars. Some of which are on gain 
antennas and can be remotely accessed to transmit. Not to mention hand held 
transceivers that might walk by. 

 

Jim, WB8VSU 

 

 

On July 24, 2023 5:51:27 PM Brian Gregory  wrote:

 

The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not a 
medical standard, but Annex A does call out the medical standard 60601-1-2 as a 
reference, as well as CENELEC 50204.  We can't figure out why;  cell phones 
produce less than half that, and our WiFi transmitter is probably 
representative, and is rated well under 1 W.  I could see a higher immunity 
standard as needed for commercial environments, say in a bank of 4-5 chargers.

 

Following along in 61000-4-3, we agree with John that residential applications 
are clearly best matched to the definition for Class 2 environment, and the 
table in Clause 5 says the limits for Class 2 equipment is 3 V/m.  20 V/m does 
not show up in Clause 5 of 61000-4-3 for any class.  

 

So, I've should to reach out to a UL standards group and find out if this is 
really necessary for residential applications.   Our local lab can't do more 
than 10, and an overseas affiliated lab is similarly limited.  I'd like to know 
were this requirement comes from.   This is more a question for EV Charging 
safety than a mainstream EMC question. 

 

As a backup, I could request a comment to Ken's point is if they define the 
peak of the modulation as 20 V/m.  I don't know where these are defined.

 

Thanks for all the detailed replies!

 

Colorado Brian 
720-450-4933



-- Original Message --
From: John Woodgate 
To: Brian Gregory 
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100

61000-4-3 is a Basic Standard. It does not specify test levels but indicates 
possible test levels. You need to look in detail at Clause 5, but look at these 
words:

 Product committees shall select the appropriate test level for each frequency 
range needing to be tested as well as the frequency ranges.

The residential environment is usually designated Class 2 (see Annex E of the 
standard), which calls for 3 V/m.

==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi (340 
- 245 BC)

On 2023-07-21 17:44, Brian Gregory wrote:

 Hello colleagues, 

 

We are building EV Chargers for residential markets (not just US) and one of 
the safety applicable standards is UL 2231-2.  It calls out  IEC 61000-4-3 for 
immunity testing parameters, which states a requirement for a field strength of 
20V/m.  Our EMC expert says typically testing is "done at 3 Vrms, which is 
standard for most products in residential environments."   He can only test up 
to 10V, and we're hearing the same from an overseas lab to whom our 
manufacturer refers.  

 

Does FCC Part B have guidelines for field strength we can cite?   Can some 
offer this "DC guy" (aka, 60 Hz) a quick definition of what the 20V/m 
represents?

 

I'm guessing 20 V/m is for higher density commercial applications, aka charging 
stations, so we probably need an exception for residential.  

 

Thank you!

 

Colorado Brian 
720-450-4933

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 
 All emc-pstc postings are archived and searchable on the 
web at: 
https://www.mail-archive.com/emc-pstc@listserv.ieee.org/

Website: https://ewh.ieee.org/soc/pses/ 
Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to 
unsubscribe)
List rules: https://ewh.ieee.org/soc/pses/listrules.html

For help, send mail to the list administrators:
Mike Sherman at: msherma...@comcast.net
Rick Linford at: linf...@ieee.org

For policy que

Re: [PSES] Woodgate's reply on residential Immunity field strength

[John Woodgate]

While the vehicle is on charge or vey near a charger?

On 2023-07-24 23:12, Jim Bacher, WB8VSU wrote:
John, I have transmitter that transmits on a VHF Frequency about 2 
minutes after I shut the car off. A number of setups allow a person to 
use a hand held device to access a higher powered transceiver that is 
in the car. It's fairly common setup for highway patrol vehicles, due 
to distance from the control points.


Jim



On July 24, 2023 6:04:13 PM John Woodgate  wrote:

There are, but 20 V/m still is a very high value. One wouldn't expect 
a transmitter to be used in a car while it is on charge.


On 2023-07-24 22:57, Jim Bacher, WB8VSU wrote:
Wi-Fi and cell phones are not the only transmitters near cars. There 
are police, fire and ham radio transceivers in cars. Some of which 
are on gain antennas and can be remotely accessed to transmit. Not 
to mention hand held transceivers that might walk by.


Jim, WB8VSU


On July 24, 2023 5:51:27 PM Brian Gregory 
 wrote:


The reference for 20 V/m to EV chargers comes from UL 2231-2.  This 
is not a medical standard, but Annex A does call out the medical 
standard 60601-1-2 as a reference, as well as CENELEC 50204.  We 
can't figure out why;  cell phones produce less than half that, and 
our WiFi transmitter is probably representative, and is rated well 
under 1 W.  I could see a higher immunity standard as needed for 
commercial environments, say in a bank of 4-5 chargers.
Following along in 61000-4-3, we agree with John that residential 
applications are clearly best matched to the definition for Class 2 
environment, and the table in Clause 5 says the limits for Class 2 
equipment is 3 V/m. 20 V/m does not show up in Clause 5 
of 61000-4-3 for any class.
So, I've should to reach out to a UL standards group and find out 
if this is really necessary for residential applications.   Our 
local lab can't do more than 10, and an overseas affiliated lab is 
similarly limited.  I'd like to know were this requirement comes 
from.  This is more a question for EV Charging safety than 
a mainstream EMC question.
As a backup, I could request a comment to Ken's point is if they 
define the peak of the modulation as 20 V/m.  I don't know where 
these are defined.

Thanks for all the detailed replies!
Colorado Brian
720-450-4933


-- Original Message --
From: John Woodgate 
To: Brian Gregory 
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100

61000-4-3 is a Basic Standard. It does not specify test levels but 
indicates possible test levels. You need to look in detail at 
Clause 5, but look at these words:


/Product committees shall select the appropriate test level for 
each frequency range //needing to be tested as well as the 
frequency ranges./


The residential environment is usually designated Class 2 (see 
Annex E of the standard), which calls for 3 V/m.


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I 
understand. Xunzi (340 - 245 BC)

On 2023-07-21 17:44, Brian Gregory wrote:

 Hello colleagues,
We are building EV Chargers for residential markets (not just
US) and one of the safety applicable standards is UL
2231-2.  It calls out  IEC 61000-4-3 for immunity testing
parameters, which states a requirement for a field strength of
20V/m.  Our EMC expert says typically testing is "done at 3
Vrms, which is standard for most products in residential
environments."   He can only test up to 10V, and we're hearing
the same from an overseas lab to whom our manufacturer refers.
Does FCC Part B have guidelines for field strength we can cite?
 Can some offer this "DC guy" (aka, 60 Hz) a quick definition
of what the 20V/m represents?
I'm guessing 20 V/m is for higher density commercial
applications, aka charging stations, so we probably need an
exception for residential.
Thank you!
Colorado Brian
720-450-4933


This message is from the IEEE Product Safety Engineering
Society emc-pstc discussion list. To post a message to the
list, send your e-mail to  All emc-pstc
postings are archived and searchable on the web at:
https://www.mail-archive.com/emc-pstc@listserv.ieee.org/

Website: https://ewh.ieee.org/soc/pses/
Instructions: https://ewh.ieee.org/soc/pses/list.html
(including how to unsubscribe)

List rules: https://ewh.ieee.org/soc/pses/listrules.html

For help, send mail to the list administrators:
Mike Sherman at: msherma...@comcast.net
Rick Linford at: linf...@ieee.org

For policy questions, send mail to:
Jim Bacher at: j.bac...@ieee.org

Re: [PSES] Woodgate's reply on residential Immunity field strength

[Jim Bacher, WB8VSU]

John, I have transmitter that transmits on a VHF Frequency about 2 minutes 
after I shut the car off. A number of setups allow a person to use a hand 
held device to access a higher powered transceiver that is in the car. It's 
fairly common setup for highway patrol vehicles, due to distance from the 
control points.


Jim



On July 24, 2023 6:04:13 PM John Woodgate  wrote:
There are, but 20 V/m still is a very high value. One wouldn't expect a 
transmitter to be used in a car while it is on charge.

On 2023-07-24 22:57, Jim Bacher, WB8VSU wrote:
Wi-Fi and cell phones are not the only transmitters near cars. There are 
police, fire and ham radio transceivers in cars. Some of which are on gain 
antennas and can be remotely accessed to transmit. Not to mention hand held 
transceivers that might walk by.


Jim, WB8VSU


On July 24, 2023 5:51:27 PM Brian Gregory  wrote:


The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not 
a medical standard, but Annex A does call out the medical standard 
60601-1-2 as a reference, as well as CENELEC 50204.  We can't figure out 
why;  cell phones produce less than half that, and our WiFi transmitter is 
probably representative, and is rated well under 1 W.  I could see a higher 
immunity standard as needed for commercial environments, say in a bank of 
4-5 chargers.


Following along in 61000-4-3, we agree with John that residential 
applications are clearly best matched to the definition for Class 2 
environment, and the table in Clause 5 says the limits for Class 2 
equipment is 3 V/m.  20 V/m does not show up in Clause 5 of 61000-4-3 for 
any class.


So, I've should to reach out to a UL standards group and find out if this 
is really necessary for residential applications.   Our local lab can't do 
more than 10, and an overseas affiliated lab is similarly limited.  I'd 
like to know were this requirement comes from.   This is more a question 
for EV Charging safety than a mainstream EMC question.


As a backup, I could request a comment to Ken's point is if they define the 
peak of the modulation as 20 V/m.  I don't know where these are defined.


Thanks for all the detailed replies!

Colorado Brian
720-450-4933

-- Original Message --
From: John Woodgate 
To: Brian Gregory 
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100

61000-4-3 is a Basic Standard. It does not specify test levels but 
indicates possible test levels. You need to look in detail at Clause 5, but 
look at these words:
Product committees shall select the appropriate test level for each 
frequency range needing to be tested as well as the frequency ranges.
The residential environment is usually designated Class 2 (see Annex E of 
the standard), which calls for 3 V/m.

==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi 
(340 - 245 BC)On 2023-07-21 17:44, Brian Gregory wrote:

Hello colleagues,

We are building EV Chargers for residential markets (not just US) and one 
of the safety applicable standards is UL 2231-2.  It calls out  IEC 
61000-4-3 for immunity testing parameters, which states a requirement for a 
field strength of 20V/m.  Our EMC expert says typically testing is "done at 
3 Vrms, which is standard for most products in residential environments."   
He can only test up to 10V, and we're hearing the same from an overseas lab 
to whom our manufacturer refers.


Does FCC Part B have guidelines for field strength we can cite?   Can some 
offer this "DC guy" (aka, 60 Hz) a quick definition of what the 20V/m 
represents?


I'm guessing 20 V/m is for higher density commercial applications, aka 
charging stations, so we probably need an exception for residential.


Thank you!

Colorado Brian
720-450-4933This message is from the IEEE Product Safety Engineering 
Society emc-pstc discussion list. To post a message to the list, send your 
e-mail to  All emc-pstc postings are archived and 
searchable on the web at:

https://www.mail-archive.com/emc-pstc@listserv.ieee.org/
Website:  https://ewh.ieee.org/soc/pses/
Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to 
unsubscribe)

List rules: https://ewh.ieee.org/soc/pses/listrules.html
For help, send mail to the list administrators:
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For policy questions, send mail to:
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To unsubscribe from the EMC-PSTC list, click the following link: 
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This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to  All 
emc-pstc postings are archived and searchable on the web at:

https://www.mail-archive.com/emc-pstc@listserv.ie

Re: [PSES] Woodgate's reply on residential Immunity field strength

[Ken Javor]

AM transmissions obviously have different amplitudes when modulated than when 
not.  Above 1 GHz, where transmissions are primarily digitally encoded 
(phase/frequency shift modulation techniques where the amplitude is constant), 
I don’t believe this is the case.  So it may be that above (for instance) 1 
GHz, the IEC formula of adding the modulation depth to the cw limit (i.e,, 10 
V/m limit modulated at 80% becomes 18 V/m peak of the modulation envelope) 
ought to look more like mil and aerospace practice where the limit is the limit.

 

Just to stir the pot, it isn’t obvious to me (with a largely mil and aerospace 
background) why the IEC took this approach.  Granted AM is AM, but why not 
simply specify a limit and say that the limit is measured as the peak of the 
modulation envelope?  Assuming that say 10 V/m cw is desired, the limit is then 
expressed as 18 V/m (or 20 V/m to use round numbers).

 

-- 

Ken Javor

(256) 650-5261

 

From: Brian Gregory 
Reply-To: Brian Gregory 
Date: Monday, July 24, 2023 at 4:49 PM
To: 
Subject: Re: [PSES] Woodgate's reply on residential Immunity field strength

 

 

The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not a 
medical standard, but Annex A does call out the medical standard 60601-1-2 as a 
reference, as well as CENELEC 50204.  We can't figure out why;  cell phones 
produce less than half that, and our WiFi transmitter is probably 
representative, and is rated well under 1 W.  I could see a higher immunity 
standard as needed for commercial environments, say in a bank of 4-5 chargers.

 

Following along in 61000-4-3, we agree with John that residential applications 
are clearly best matched to the definition for Class 2 environment, and the 
table in Clause 5 says the limits for Class 2 equipment is 3 V/m.  20 V/m does 
not show up in Clause 5 of 61000-4-3 for any class.  

 

So, I've should to reach out to a UL standards group and find out if this is 
really necessary for residential applications.   Our local lab can't do more 
than 10, and an overseas affiliated lab is similarly limited.  I'd like to know 
were this requirement comes from.   This is more a question for EV Charging 
safety than a mainstream EMC question. 

 

As a backup, I could request a comment to Ken's point is if they define the 
peak of the modulation as 20 V/m.  I don't know where these are defined.

 

Thanks for all the detailed replies!

 

Colorado Brian 
720-450-4933



-- Original Message --
From: John Woodgate 
To: Brian Gregory 
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100

61000-4-3 is a Basic Standard. It does not specify test levels but indicates 
possible test levels. You need to look in detail at Clause 5, but look at these 
words:

 Product committees shall select the appropriate test level for each frequency 
range needing to be tested as well as the frequency ranges.

The residential environment is usually designated Class 2 (see Annex E of the 
standard), which calls for 3 V/m.

==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi (340 
- 245 BC)

On 2023-07-21 17:44, Brian Gregory wrote:

 Hello colleagues, 

 

We are building EV Chargers for residential markets (not just US) and one of 
the safety applicable standards is UL 2231-2.  It calls out  IEC 61000-4-3 for 
immunity testing parameters, which states a requirement for a field strength of 
20V/m.  Our EMC expert says typically testing is "done at 3 Vrms, which is 
standard for most products in residential environments."   He can only test up 
to 10V, and we're hearing the same from an overseas lab to whom our 
manufacturer refers.  

 

Does FCC Part B have guidelines for field strength we can cite?   Can some 
offer this "DC guy" (aka, 60 Hz) a quick definition of what the 20V/m 
represents?

 

I'm guessing 20 V/m is for higher density commercial applications, aka charging 
stations, so we probably need an exception for residential.  

 

Thank you!

 

Colorado Brian 
720-450-4933

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Re: [PSES] Woodgate's reply on residential Immunity field strength

[John Woodgate]

There are, but 20 V/m still is a very high value. One wouldn't expect a 
transmitter to be used in a car while it is on charge.


On 2023-07-24 22:57, Jim Bacher, WB8VSU wrote:
Wi-Fi and cell phones are not the only transmitters near cars. There 
are police, fire and ham radio transceivers in cars. Some of which are 
on gain antennas and can be remotely accessed to transmit. Not to 
mention hand held transceivers that might walk by.


Jim, WB8VSU


On July 24, 2023 5:51:27 PM Brian Gregory  
wrote:


The reference for 20 V/m to EV chargers comes from UL 2231-2.  This 
is not a medical standard, but Annex A does call out the medical 
standard 60601-1-2 as a reference, as well as CENELEC 50204.  We 
can't figure out why;  cell phones produce less than half that, and 
our WiFi transmitter is probably representative, and is rated well 
under 1 W.  I could see a higher immunity standard as needed for 
commercial environments, say in a bank of 4-5 chargers.
Following along in 61000-4-3, we agree with John that residential 
applications are clearly best matched to the definition for Class 2 
environment, and the table in Clause 5 says the limits for Class 2 
equipment is 3 V/m.  20 V/m does not show up in Clause 5 of 61000-4-3 
for any class.
So, I've should to reach out to a UL standards group and find out if 
this is really necessary for residential applications.   Our local 
lab can't do more than 10, and an overseas affiliated lab is 
similarly limited.  I'd like to know were this requirement comes 
from.   This is more a question for EV Charging safety than 
a mainstream EMC question.
As a backup, I could request a comment to Ken's point is if they 
define the peak of the modulation as 20 V/m.  I don't know where 
these are defined.

Thanks for all the detailed replies!
Colorado Brian
720-450-4933


-- Original Message --
From: John Woodgate 
To: Brian Gregory 
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100

61000-4-3 is a Basic Standard. It does not specify test levels but 
indicates possible test levels. You need to look in detail at Clause 
5, but look at these words:


/Product committees shall select the appropriate test level for each 
frequency range //needing to be tested as well as the frequency ranges./


The residential environment is usually designated Class 2 (see Annex 
E of the standard), which calls for 3 V/m.


==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. 
Xunzi (340 - 245 BC)

On 2023-07-21 17:44, Brian Gregory wrote:

 Hello colleagues,
We are building EV Chargers for residential markets (not just US)
and one of the safety applicable standards is UL 2231-2.  It
calls out  IEC 61000-4-3 for immunity testing parameters, which
states a requirement for a field strength of 20V/m.  Our EMC
expert says typically testing is "done at 3 Vrms, which is
standard for most products in residential environments."   He can
only test up to 10V, and we're hearing the same from an overseas
lab to whom our manufacturer refers.
Does FCC Part B have guidelines for field strength we can cite? 
 Can some offer this "DC guy" (aka, 60 Hz) a quick definition of
what the 20V/m represents?
I'm guessing 20 V/m is for higher density commercial
applications, aka charging stations, so we probably need an
exception for residential.
Thank you!
Colorado Brian
720-450-4933


This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. To post a message to the list, send
your e-mail to  All emc-pstc postings are
archived and searchable on the web at:
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This message is from the IEEE Product Safety Engineering Society 
emc-pstc discussion list. To post a message to the list, send your 
e-mail to All emc-pstc postings are archived and searchable on the 
web at:

https://www.mail-archive.com/e

Re: [PSES] Woodgate's reply on residential Immunity field strength

[Jim Bacher, WB8VSU]

Wi-Fi and cell phones are not the only transmitters near cars. There are 
police, fire and ham radio transceivers in cars. Some of which are on gain 
antennas and can be remotely accessed to transmit. Not to mention hand held 
transceivers that might walk by.


Jim, WB8VSU


On July 24, 2023 5:51:27 PM Brian Gregory  wrote:


The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not 
a medical standard, but Annex A does call out the medical standard 
60601-1-2 as a reference, as well as CENELEC 50204.  We can't figure out 
why;  cell phones produce less than half that, and our WiFi transmitter is 
probably representative, and is rated well under 1 W.  I could see a higher 
immunity standard as needed for commercial environments, say in a bank of 
4-5 chargers.


Following along in 61000-4-3, we agree with John that residential 
applications are clearly best matched to the definition for Class 2 
environment, and the table in Clause 5 says the limits for Class 2 
equipment is 3 V/m.  20 V/m does not show up in Clause 5 of 61000-4-3 for 
any class.


So, I've should to reach out to a UL standards group and find out if this 
is really necessary for residential applications.   Our local lab can't do 
more than 10, and an overseas affiliated lab is similarly limited.  I'd 
like to know were this requirement comes from.   This is more a question 
for EV Charging safety than a mainstream EMC question.


As a backup, I could request a comment to Ken's point is if they define the 
peak of the modulation as 20 V/m.  I don't know where these are defined.


Thanks for all the detailed replies!

Colorado Brian
720-450-4933

-- Original Message --
From: John Woodgate 
To: Brian Gregory 
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100



61000-4-3 is a Basic Standard. It does not specify test levels but 
indicates possible test levels. You need to look in detail at Clause 5, but 
look at these words:
Product committees shall select the appropriate test level for each 
frequency range needing to be tested as well as the frequency ranges.
The residential environment is usually designated Class 2 (see Annex E of 
the standard), which calls for 3 V/m.

==
Best wishes John Woodgate OOO-Own Opinions Only
www.woodjohn.uk
Rayleigh, Essex UK

I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi 
(340 - 245 BC)On 2023-07-21 17:44, Brian Gregory wrote:

Hello colleagues,

We are building EV Chargers for residential markets (not just US) and one 
of the safety applicable standards is UL 2231-2.  It calls out  IEC 
61000-4-3 for immunity testing parameters, which states a requirement for a 
field strength of 20V/m.  Our EMC expert says typically testing is "done at 
3 Vrms, which is standard for most products in residential environments."   
He can only test up to 10V, and we're hearing the same from an overseas lab 
to whom our manufacturer refers.


Does FCC Part B have guidelines for field strength we can cite?   Can some 
offer this "DC guy" (aka, 60 Hz) a quick definition of what the 20V/m 
represents?


I'm guessing 20 V/m is for higher density commercial applications, aka 
charging stations, so we probably need an exception for residential.


Thank you!

Colorado Brian
720-450-4933This message is from the IEEE Product Safety Engineering 
Society emc-pstc discussion list. To post a message to the list, send your 
e-mail to  All emc-pstc postings are archived and 
searchable on the web at:

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-

Re: [PSES] Woodgate's reply on residential Immunity field strength

[Brian Gregory]

 The reference for 20 V/m to EV chargers comes from UL 2231-2.  This is not a 
medical standard, but Annex A does call out the medical standard 60601-1-2 as a 
reference, as well as CENELEC 50204.  We can't figure out why;  cell phones 
produce less than half that, and our WiFi transmitter is probably 
representative, and is rated well under 1 W.  I could see a higher immunity 
standard as needed for commercial environments, say in a bank of 4-5 chargers. 
Following along in 61000-4-3, we agree with John that residential applications 
are clearly best matched to the definition for Class 2 environment, and the 
table in Clause 5 says the limits for Class 2 equipment is 3 V/m.  20 V/m does 
not show up in Clause 5 of 61000-4-3 for any class.   So, I've should to reach 
out to a UL standards group and find out if this is really necessary for 
residential applications.   Our local lab can't do more than 10, and an 
overseas affiliated lab is similarly limited.  I'd like to know were this 
requirement comes from.   This is more a question for EV Charging safety than a 
mainstream EMC question.  As a backup, I could request a comment to Ken's point 
is if they define the peak of the modulation as 20 V/m.  I don't know where 
these are defined. Thanks for all the detailed replies! Colorado Brian 
720-450-4933

-- Original Message --
From: John Woodgate 
To: Brian Gregory 
Subject: Re: [PSES] Immunity test field strength, residential setting
Date: Fri, 21 Jul 2023 18:05:59 +0100


61000-4-3 is a Basic Standard. It does not specify test levels but indicates 
possible test levels. You need to look in detail at Clause 5, but look at these 
words:
 Product committees shall select the appropriate test level for each frequency 
range needing to be tested as well as the frequency ranges.
The residential environment is usually designated Class 2 (see Annex E of the 
standard), which calls for 3 V/m.
==
 Best wishes John Woodgate OOO-Own Opinions Only
 www.woodjohn.uk
 Rayleigh, Essex UK
 
 I hear, and I forget. I see, and I remember. I do, and I understand. Xunzi 
(340 - 245 BC)On 2023-07-21 17:44, Brian Gregory wrote: Hello colleagues,  We 
are building EV Chargers for residential markets (not just US) and one of the 
safety applicable standards is UL 2231-2.  It calls out  IEC 61000-4-3 for 
immunity testing parameters, which states a requirement for a field strength of 
20V/m.  Our EMC expert says typically testing is "done at 3 Vrms, which is 
standard for most products in residential environments."   He can only test up 
to 10V, and we're hearing the same from an overseas lab to whom our 
manufacturer refers.   Does FCC Part B have guidelines for field strength we 
can cite?   Can some offer this "DC guy" (aka, 60 Hz) a quick definition of 
what the 20V/m represents? I'm guessing 20 V/m is for higher density commercial 
applications, aka charging stations, so we probably need an exception for 
residential.   Thank you! Colorado Brian 
 720-450-4933This message is from the IEEE Product Safety Engineering Society 
emc-pstc discussion list. To post a message to the list, send your e-mail to 
 All emc-pstc postings are archived and searchable on the 
web at: 
 https://www.mail-archive.com/emc-pstc@listserv.ieee.org/
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 Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to 
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 List rules: https://ewh.ieee.org/soc/pses/listrules.html
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 Mike Sherman at: msherma...@comcast.net
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-

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_
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