> Paul, you have to have a line transformer for isolation -
> it is life and death - no discussion possible...
Not that he should do it (for other reasons), but there is a
great deal of equipment we use every day that runs power
supplies that are not isolated from the power line.
The problem is getting the home builder to understand what
to do to make it safe.
Switch mode power supplies run directly across the power
line, as do many TV sets and computer supplies. They do the
isolation later, after the power line is rectified,
filtered, and chopped back into higher frequency AC.
In contrast to that there are many devices built by Hams
that use transformers and are not safe. Some even appeared
in the ARRL Handbook over the years. Just look closely and
you will find many Ham projects that connect one side of a
filament transformer primary or blower to the chassis.
It depends more how you do things than anything else. If the
neutral of the mains connects to the chassis it is not safe.
This is especially true when the chassis is a common point
for 120V systems like blowers, relays, or filament
transformers.
73 Tom
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