rustybkts wrote:
I have seen it mentioned before that the Manzanita chargers are not isolated
from the mains.
As this is inherently very dangerous, I am surprised they are even allowed
to be sold and have never heard of any non isolated power supply being
available in Europe.
Can anyone expand on how this can be allowed?
1. Regulatory standards are *voluntary* in most parts of the USA. Safety
agency listings like UL, ETL, etc. are not required by law, except in
a few places where local ordinances have been passed to require it.
(Two places I know of are Chicago IL and Los Angeles CA).
Thus, you can sell just about anything. The limiting factor is that
the seller can be SUED if the product causes damage or injury. Most
companies decide to get a safety agency listing (like UL or ETL) so
they can testify in court that their product has been tested and
met safety standards.
2. Non-isolated products are very common. Many consumer products leave
out isolation as a cost-cutting measure. Toasters, stoves, dryers,
air conditioners, and pretty much all high-power products are not
isolated.
However, there are safety standards that apply to such products.
The standards say that the case must be grounded, there must be
no possible way for a consumer to touch any of the potentially
"hot" wires coming from it, and it must have extra-strong insulation
between anything the consumer can touch and the AC line. Again,
complying with the standards is voluntary, though most manufacturers
follow them to avoid being bankrupt by lawsuits.
> A simple component failure will expose the output terminals to the
> mains supply.
Actually, the output terminals are *always* connected to the mains
supply. In effect, the charger is a bridge rectifier from the AC line to
the output terminals, plus a non-isolated buck/boost voltage converter.
--
Lee A. Hart | Ring the bells that still can ring
814 8th Ave N | Forget the perfect offering
Sartell MN 56377 | There is a crack in everything
leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
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