Re: Battery Boxes...What One Company Designed

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On 18 Sep 2005 05:13:37 GMT, ddl@danlan.*com (Dan Lanciani) wrote in message
<1331587@xxxxxxxxxxxxxxxxxxx>:

>In article <ehopi1lk9nh29a8u247sbu1o1tt5cm65la@xxxxxxx>,
MFHult@xxxxxxxxxxxxxxxxxxxxx (Marc F Hult) writes:
>| On 18 Sep 2005 02:52:12 GMT, ddl@danlan.*com (Dan Lanciani) wrote in message
>| <1331585@xxxxxxxxxxxxxxxxxxx>:
>|
>| >In article <as8pi1da45o1psehe0s983ql7439j8k3ek@xxxxxxx>,
>| MFHult@xxxxxxxxxxxxxxxxxxxxx (Marc F Hult) writes:
>|
>| >|
>| >|
>| >| Inteli-Power PD9180 and PD9160 (now Progressive Dynamics) as I wrote in my
>| >| previous post. See
>| >|
>| >| http://www.progressivedyn.com/power_converters.html
>| >
>| >Interesting.  I had no idea that you could get class 2 supplies with such
>| >high power output.  Maybe I'll have to reconsider my low-voltage
distribution
>| >analysis...
>| >
>|
>[...]
>| IMO, Key here is UL and internal transformer isolation. But I haven't probed
to
>| see whether it is specifically UL for Class 2. I am satisfied that it means
>| engineering needs.
>
>Hmm.  But if it isn't UL listed as a class 2 supply then it can't supply class
>2 circuits.  Class 2 supplies have some pretty stringent requirements for
>current limiting (not just over current protection--source impedance is a
>consideration).  Last time I checked the most power allowed for a class 2
>supply in the lowest voltage range was 100VA.  (At higher voltages the power
>is reduced disproportionately IIRC.)

Interesting.

Thanks for the clarification about Class 2. I musta had at least NEC Class 2 and
Class I, Division 2 all jumbled up ;-)

It would appear that the listing for the PD91x0 devices is probably UL 458 ("
Chargers or charging functions incorporated into converter or inverters for use
in recreational vehicles and boats, as covered by the Standard for Power
Converters/Inverters and Power Converter/Inverter Systems for Land Vehicles and
Marine Crafts").

For home use, they may need to be listed under UL 1012.  " These requirements
cover portable, stationary, and fixed power units having an input rating of 600
volts or less, direct- and alternating- current, with at least one output not
marked Class 2, and that are intended to be employed in ordinary locations in
accordance with the National Electrical Code, ANSI/NFPA 70." ) I dunno.

http://search.globalspec.com/engineering-search/engineering-standards/abstract
/24003535340/UL_Standard_for_Safety_Power_Units_Other_Than_Class_2

http://ulstandardsinfonet.ul.com/scopes/1012.html


Previously I identified four sections of the code that seem to pertain:

Article 411 lighting  (isolated; <30 volts/42.4v peak); max 20 amp branch
circuit supply; max 25amp lighting circuit; Class 2 power source; not grounded )

Article 720  ( <50 volts; =>12AWG wiring; Article 240 overcurrent )

Article 725.21 Class 1 ( <30 volts and <1000 volt-amp )

Article 725 Class 2  (supplying or active converting <100 watts at =<30VAC or
=<60vdc )

Power for telcomm equipment is yet another set of NEC provisions that may
pertain depending on what it being powered.

Article 411 is not particularly useful because it appears to pertain to a
complete unit that is UL listed as a system. One can buy low voltage wiring
systems as a package that conform to 411 that use bare wires a few inches from a
tall person's head. But if is unclear that one can substitute or fix anything
and still be compliant. Note the "Class 2 power source requirement" .

Article 720 is where I should have indicated that the DC _supply_ to my
low-voltage lighting dimmers fall. As practical matter, one uses conventional (
Sect 1-4 ANSI/NFPA 70) wiring  but keeps these conductors out of conduits and
boxes that also contain 120/220 VAC. My DC dimmer panel is about 4 feet from the
PD91x0  supplies so this is easy to do.

Article 725.21 Class 1 (not 2  Thank you ;-) ) would seem to pertain to (in my
case) to:

1) The distribution of power from the centrally-located DC lighting dimmers
(24vdc input, 0-12vdc output) to my commercial track lighting that is UL-listed
for remote transformers.

http://www.ipnlighting.com/faq/linear_faqs.htm

Each dimmer is rated at 250 watts and has its own 20 amp breaker.

2) The distribution of power from the 12vdc supply (tap) of my system  (80 x 12
= 960 < 1000v-a) as 725.21 Class 1

So the principal questions would seem to revolve around

1) UL 458 vs UL 1012(?) listing of the PD91x0 charger/supplies

2) Use of Class 2 DC-DC converters such as

http://www.axiomatic.com/24vdc-power-supply.html
http://www.ecnmag.com/article/CA502827.html?filename=ECN20050201ec51ps616.xml
to provide a Class 2 source from Art 720 distribution

3) Compliance with Art 720 + Art 240, rather than Art 725, if listed Class 2
DC-DC converters are not used.

Power for telcomm equipment is yet another set of NEC provisions that may
pertain depending on what it being powered.


... Marc
Marc_F_Hult
www.ECOntrol.org