On Jan 19, 2009, at 09:47:55 -0800, Chuck Guzis" wrote:
On 19 Jan 2009 at 11:17, Jules Richardson wrote:
It's always surprised me that stuff like
that's legal in the US,
given the
nature of the power outlets; it doesn't need a lot of weight for
the device
plugged into the wall to tilt slightly and risk the exposure of
live metal
contacts (heck, normal power cords and pets are a bad enough
combination :-)
Electrical safety requirements and certification in the US is a hodge-
podge of private (e.g. Underwriters Labs), state and local building
code) and Manufacturers and trade associations (NEC, IEEE "green
book"). Action with individual products is taken on a Federal level
only when a sufficient number of episodes have shown a device to pose
a danger (Consumer Product Safety Commission). AFAIK, there are no
Federal standards for electrical product safety--although there are
for RF emission.
Basically, it's cowboy electrical safety when it comes to consumer-
level mains-operated devices.
Basically, in the US the UL is the standard which one follows (CE if
you want to go elsewhere). Failing to meet the UL/CE standards
generally has force of law in the US due to the ever diligent lawyers.
Failure to meet (and get fully tested and certified) opens one up to a
suit where one has to prove that the design is safe. Whereas, if
certified, the suer has to prove either negligence on the part of the
manufacturer or show that the certification is at fault. The latter
rarely happens. Extensions to the NEC (National Electrical Codes - a
published standard which is implemented locally) rarely step into the
areas where the UL/CE standards bear. However, some localities can't
keep their hands out of the pie...
Wall warts relieve the manufacturer of a product of having to certify
the product to the lebenty-leben, various, multitudinous and sundry
standards since the w/w manufacture does this for you. The low voltage
output eliminates all the mains testing and certification. To give you
an idea, the difference in testing and certifying one of our product
with an internal supply and one using a wart exceeded $20k and that
was over 15 years ago. Since this was a fairly low volume device you
can guess the direction we went. Even using a certified power supply
requires that the entry and attachment be certified if not provided by
the p/s manufacturer.
If one wants to be a cowboy and manufacture a consumer-level mains-
operated device without certification, make sure all your assets are
safely ensconced in a Cayman Island account.
CRC