Generally, UL standards will state that a device on a non-primary circuit of
less than 42.4V with a current capability of under 8A is basically a
non-problem. Rememberthat UL came about as a means to minimize the risk of
fires by applying standardized safety specs. Hence, we have standard control
voltages that are well below 42.4V today. Wall warts may be ugly, but they
can save many hassles and much expense in the listing or approval process.
The reason for their existance may be another cause-effect thing created by
UL.

Chris

> -----O
>
> On Thu, 7 Mar 2002 08:29:53 -0700 Micro Eng <micro_eng@HOTMAIL.COM>
> writes:
> > so...is it a way to get around the UL approved if you use a walwart
> > that has
> > been approved?  UL only is worried about the AC side of things and
> > not what
> > is the DC?
>
>         Powering it with a wall wart makes it easier to get
> through safety
> listings. We're currently using ETL to test to UL standards.
> Our products
> are ETL listed.
>
> >
> > Then thier is FCC approval...does it apply to consumer things that
> > are not
> > computers yet have a micro in them?  I heard once that anything
> > under 1MHz
> > does not need the Class B approval
> >
>
>         There are a few exemptions.  See
> http://www.hallikainen.org/cgi-bin/section.pl?section=15.103
> . Possibly
> the exemption that is easiest to get is for low frequency battery
> operated equipment:
>
>     (h) Digital devices in which both the highest frequency generated
> and the highest frequency used are less than 1.705 MHz and
> which do not
> operate from the AC power lines or contain
> provisions for operation while connected to the AC power
> lines. Digital
> devices that include, or make provision for the use of, battery
> eliminators, AC adaptors or battery chargers which permit operation
> while charging or that connect to the AC power lines indirectly,
> obtaining their power through another device which is connected to the
> AC power lines, do not fall under this exemption.
>
>
> Harold

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