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#48305 02/09/05 12:58 AM
Joined: Dec 2002
Posts: 18
H
Member
Why is it when you have a switched outlet (the top is switched and the bottom is always hot), you turn off the switch that there is still 50 volts reading on the switch leg? When you ground the switch leg the voltage goes away? Electrical phenomenon?

#48306 02/09/05 02:18 AM
Joined: Jul 2004
Posts: 9,923
Likes: 32
G
Member
That is just a problem with these new high impedance meters. Withno load on the line you will see antenna effect.


Greg Fretwell
#48307 02/09/05 05:49 AM
Joined: Jan 2003
Posts: 4,391
I
Moderator
NEMA calls this 'phantom voltage' and it is real voltage with almost no current.

The wire that you are getting 50 volts on is picking this up simple by running next to other live wires.

You meter draws so little current it can measure this phantom voltage.

Try the same thing with an older analog meter.

Or use a set of Wiggys and a digital at the same time and you will see 0 volts on the digital.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#48308 02/09/05 06:55 AM
Joined: Oct 2004
Posts: 48
M
Member
A (near) full description of this can be found here .

M.


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