Dear Moshe,

I assume you mean creepages and clearances between input 
circuits and SELV circuits (and not conductors). I am also 
assuming  you are familiar with the clearance and creepage Tables 
in UL1950 and/or EN 60950 which depends on the Installation 
Category and Pollution Degree.

In regards to insulation for North America, because of limitations on 
TNV circuits, a max 72 Vdc supply is considered a secondary 
hazardous circuit. If you do not have the required insulation 
between these circuits (basic or reinforced insulation depending on 
whether circuits are reliably earthed or not), the standard allows 
you to interconnect the two circuits if abnormals are done between 
components in the two circuits and you still maintain the criteria for 
SELV voltage limits. Regret I cannot reference the claues at this 
time since I am at home and not in our laboratories. 

For Europe, the max 72 Vdc supply circuit can be considered a 
TNV-2 circuit if not subject to overvoltages. In this case, between a 
TNV-2 circuit and SELV, you need to comply with the basic 
insulation requirements and also the Dielectric Sterngth or Impulse 
Test requirements (again I do not have the standard to give you 
details).

I suggest for worldwide Approvals, you consider the strictest of  the 
above specified requirements. 

Although you have not asked, do not forget that in the US, a 
means for connection to the supply is needed in accordance to the 
NEC, such as a field wiring compartment with terminal blocks or 
min 6 inch pigtail leads. A compartment (with knockouts or holes 
for field wiring) is not needed for equipment to be Recognized or 
which is intended for Restricted Access Locations (RAL). In the 
latter case, instructions are needed for routing of the field wiring so 
that they are not damaged during installation and normal use of 
your equipment.

Hope this helps.


Best Regards, 


From:                   mvald...@netvision.net.il
Date sent:              Wed, 21 Oct 98 00:44:09 PDT
Subject:                isolation of battery (72V max) input
To:                     emc-p...@ieee.org, t...@world.std.com
Send reply to:          mvald...@netvision.net.il

> Hello everyone,
> 
> What are creepage/clearance requirements between battery (60V nominal which 
> could go to 72V) 
> conductors and SELV conductors? The equipment resides in "CO like" 
> environment.
> 
> thanks in advance,
> Moshe
> --------------------------------------------
> Name: moshe valdman
> E-mail: mvald...@netvision.net.il
> Phone: 972-52-941200
> Telefax: 972-3-5496369
> Date: 21/10/98
> Time: 0:44:10
> You are most welcome to visit my homepage at:
> 
> http://www.geocities.com/CapeCanaveral/5233/
> --------------------------------------------
> 
> 
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