Hello all and please dont flame me if I am posting to the wrong group.
I wish to measure voltage on an a/c unit that is 220v.I know how to do
this with 12v systems(one lead to wire,other to ground)and I wonder if
it is the same deal for 220v.
I ask because the amperage invovled in a 220 line is capable of
killing as opposed to a 12v system and I want to be safe than sorry.
Can somebody please let me know the proper way or point me in the
Thank you in advance
No....220VAC is not 12DC....and no, on an AC unit, if you dont know how its
wired, you can look all day, and if you are going to ground, even if one leg
is dead, you will real 110VAC all day...220VAC you do not read to ground...
First, if you have no clue, you need to stop now, and no, altho I do this on
a daily basis, I wont be the one to tell you how to check on a unit I cant
see, and I will tell you that not only can the 220 kill you in the unit, so
can the 24VAC since its got several amps on it....
1VAC can kill...its not the voltage, its the amperage, and 1 amp can kill
you....even a 12V system...
Your yellow pages, under heating and air contractors.
You might be surprised...some of us are not as expensive as you would like
Hell...if you are in my service area, to keep you from messing up, and
getting hurt, I would check it for free for you...beat that...and yes, I am
in the trade, and yes, I see this all the time, and yes, normally it ends up
being something simple..
THE safety rule when working with AC is "Don't touch metal unless it is
GROUNDed or the power is off,
That's why the probes of the DVM are insulated. For most AC work, you want
to use identical (except for color) probes for both inputs to you meter.
You find a way of holding your meter so that you can see it while you
operate the probes with two hands.
You can quickly take any voltage reading necessary. If you want voltage to
ground, you touch one probe tip (either one, in AC is doesn't matter) to
ground and the other to whatever you wish to measure. In a 220 volt
circuit, you should measure 220 (240) voltage between the two hot wires and
110 (120) volts between either hot and ground. BUT you ALWAYS take the
hot/hot measurement. Don't ASSume that because each hot is 120 voltage the
hot to hot voltage is 240.
Thanks to everyone who replied.I decided not to mess with it because I
am not comfortable working with high voltage.It was later determined
that the compressor was drawing too much current on start up,which was
causing all the trouble.So I said screw it and went and got me a new
Thanks again everyone.
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