In article ,
KC8QJP wrote:

cut the ground off the blanket that will make the hum go away

That strikes me as very poor advice, for three reasons:

[1] I've never seen an electric blanket or bed-heating pad here in the
U.S. which *has* a ground prong. They all use two-wire
(hot/neutral) plugs.

[2] If there *is* a ground prong on a device which is used in close
proximity to a human body, it's probably there for a very good
reason (safety). Removing a safety ground from such a device
seems like a really bad idea.

[3] If the reason for the humming is a harmonic-currents problem (as I
suspect) then it has *nothing* to do with the presence or absence
of a ground connection. It's due to irregular current flows on
the hot and neutral wires. Floating the device free from the
safety ground will have not reduce the problem at all.

"Floating" an equipment-chassis ground can sometimes help reduce hum
in audio/video equipment if the hum is due to a ground loop. I don't
believe that ground loops have anything at all to do with the original
poster's buzzing-transformer problem.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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