Grounding the Circut

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Old 04-15-12, 06:25 PM
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Grounding the Circut

Hello all,
This is my first time posting here but I read this blog weekly. I ran into an interesting situation this weekend while doing some electrical work. I am moving my washer/dryer into a closet so i had to run wiring from an existing light to an outlet so I can plug in the washer. In the process I was using my non contact voltage tester to make sure the outlet was working. As I did this, I noticed that when I put the voltage tester to the face/body of the washing machine itself the tester beeped and lit up as if there was electricity flowing through the entire machine. I thought this was odd, so I took an extension cord and plugged the washing machine into one end, and plugged it into an outlet on a different circut, when I put the tester on the washing machine again, it did not beep or light up. As a last test, I plugged the extension cord/washing machine into a different outlet (which I did not alter) on the same circuit as the first, and again as I put the non contact voltage tester to the washing machine, it lit up and beeped. Now, I am worried something is wrong with the entire circut, maybe it isn't grounded???

I tried looking everywhere as to why the voltage tester would read the washing machine as being "live" but have had no success, any help is appreciated. Thanks in advance.
 
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Old 04-15-12, 07:04 PM
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Basically a non-contact tester measures electromagnetic fields not voltage. For a pro who understands its limitations it can be a valuable tool. For an amateur it can easily run you on a wild goose chase. You can have an electromagnetic fields without any significant power.

Now, I am worried something is wrong with the entire circut, maybe it isn't grounded
The reading likely has nothing to do with the circuit ground. In fact a circuit can have no ground and still be good. Ground just adds extra safety. Once up on a time almost all circuits were ungrounded.
 
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Old 04-16-12, 05:28 PM
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Great, that is good to know sounds like I shouldn't worry.

Just for the sake of my own curiosity, would there be any reason why some outlets I plug the machine into create this field while other outlets do not?
 
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Old 04-16-12, 05:40 PM
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Just for the sake of my own curiosity, would there be any reason why some outlets I plug the machine into create this field while other outlets do not?
Possibly, but we'd be off into hypothetical stuff there. Just for the sake of my curiosity, have you tested the various receptacles with a receptacle tester?
 
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Old 04-16-12, 05:45 PM
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I did test the receptacles with a receptacle tester and everything read as correct
 
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Old 04-16-12, 06:05 PM
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One more interesting thing I just found. I just tested the outlet on the circut we installed, using an analogue voltmeter set to 250V, as well as other outlets on the same fuse/breaker and found that white to black reads 150V, while white to ground reads 40V. However, other outlets in the house we haven't messed with also read 150V black to white, but 0V white to ground.

Any thoughts?
 
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Old 04-16-12, 06:32 PM
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Just one: possibly the wire insulation was damaged at some point. Is this circuit AFCI protected? If not, should it be under current code?

If it isn't, I think I would try replacing the breaker with a combo AFCI and seeing if that would hold. If it did, I would sleep easy. If not, I would be checking the wiring down the line.

Just a thought.
 
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Old 04-16-12, 06:49 PM
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One more interesting thing I just found. I just tested the outlet on the circut we installed, using an analogue voltmeter set to 250V, as well as other outlets on the same fuse/breaker and found that white to black reads 150V, while white to ground reads 40V. However, other outlets in the house we haven't messed with also read 150V black to white, but 0V white to ground.
150 volts is a out of the normal range for household voltage and could cause damage to equipment. I know I got some screwy voltage readings one time and found out it was my voltmeter's batteries going bad. Analog meters I would not think be affected by this. Take a voltage reading on other circuits and see what you get. Something may be a foot here.

On a side note: You should not run the washer off your lighting circuit. It really should have it own circuit.
 
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Old 04-17-12, 06:06 AM
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I checked the other outlets in the house and they also read 150V.
 
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Old 04-17-12, 06:34 AM
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If you create a new washing machine location including hose hookups, such as in a closet, then you should run a new 12 gauge 20 amp. 120 volt circuit for that washing machine area only, ending in an ordinary duplex receptacle (or a single 20 amp rated receptacle).

However nothing prevents you from plugging the washing machine into an existing nearby receptacle provided you do not run an extension cord through a doorway or under a carpet or through staples on the wall.

A separately run ground wire all the way up from the panel can be used to legitimatize a 3 prong receptacle installed where a 2 prong receptacle used to be. This need not follow the route of the circuit wiring. The body or frame of a washing machine or other appliance, or the chassis of electronic equipment, may be bonded via a wire to anything you determine to be or figure out to be grounded.
 

Last edited by AllanJ; 04-17-12 at 06:50 AM.
  #11  
Old 04-17-12, 07:52 AM
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Ok, so I bought a new multimeter and all outlets (ones we put in and the original onese) read 120V from black to white. However, the outlets we put in still read 40V white to ground, and 80V black to ground...does this mean the black is leaking voltage somewhere? If not what does it mean?
 
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Old 04-17-12, 08:19 AM
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Plug a hair dryer into one half of the receptacle while you measure hot to neutral (black to white) of the other half. YOu should get an almost steady 120 volts when the hair dryer is turned off and on.

If not then there is a neutral problem.

If hot to neutral is okay but neutral to ground registers some voltage (more than two volts) then there is a problem (loose connection?) somewhere in the ground path back to the panel.
 
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Old 04-17-12, 08:22 AM
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However, the outlets we put in still read 40V white to ground, and 80V black to ground...does this mean the black is leaking voltage somewhere? If not what does it mean?
No,more likely it means a bad ground. You need to check all connections. Does the ground come directly from the breaker box or is it fed from another device box? Does it depend on old style BX cable at some point?
 
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Old 04-17-12, 04:40 PM
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There is a problem with a neutral connection in the circuit.
 
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