Hot, Neutral & Ground... voltage question.

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pegggu

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if you have a 120v system (1 hot, 1 neutral).
essentially, is the neutral not a hot/live conductor, as it is an AC system that the current alternates?

if you were to measure voltage from hot to ground you'd get 120v.
if you were to measure voltage from neutral to ground, would you not get 120v as well?

thanks!
 
pegggu said:
if you have a 120v system (1 hot, 1 neutral).
essentially, is the neutral not a hot/live conductor, as it is an AC system that the current alternates?

if you were to measure voltage from hot to ground you'd get 120v.
if you were to measure voltage from neutral to ground, would you not get 120v as well?

thanks!
Click to expand...

No..... Measuring voltage from neutral to ground should ideally be 0 volts...
 
pegggu said:
if you have a 120v system (1 hot, 1 neutral).
essentially, is the neutral not a hot/live conductor, as it is an AC system that the current alternates?
Click to expand...

to answer this question, according to the code the neutral is a current carrying conductor in this case. so yes I would consider it "hot/live" because any residual current from the load will flow back through the neutral.
 
lielec11 said:
. . . I would consider it "hot/live" because any residual current from the load will flow back through the neutral.
Click to expand...
Not just "residual." For a single phase 120 volt circuit, 100% of the current flowing through the hot conductor will return to the source via the neutral conductor. I agree that in an ideal world, the voltage from neutral to ground will be zero. The world is not ideal, however, and there will be some measureable voltage between those two points.

 
charlie b said:
Not just "residual." For a single phase 120 volt circuit, 100% of the current flowing through the hot conductor will return to the source via the neutral conductor. I agree that in an ideal world, the voltage from neutral to ground will be zero. The world is not ideal, however, and there will be some measureable voltage between those two points.

Click to expand...

I agree... Usually there is a small voltage measurement between the neutral conductor and the EGC. I have measured at times and have found this to be @ 1 or 2 volts, but the voltage is dependent upon load current. :)
 
If the "system" is just 120 volts, not 120/240 single phase 3-wire, then there is no neutral, just one ungrounded conductor and one grounded conductor.

Tapatalk!
 
JoeStillman said:
But this is rare.
Click to expand...
Which reminds me...

I was driving on a rural road the other day and I noticed a string of utility poles paralleling the roadway for quite a distance. It looked like a medium voltage overhead distribution line, except there was only one conductor.
 
ggunn said:
Which reminds me...

I was driving on a rural road the other day and I noticed a string of utility poles paralleling the roadway for quite a distance. It looked like a medium voltage overhead distribution line, except there was only one conductor.
Click to expand...

Nothing wrong with that IMHO. perhaps they are getting ready for residential feeds
 
ggunn said:
Which reminds me...

I was driving on a rural road the other day and I noticed a string of utility poles paralleling the roadway for quite a distance. It looked like a medium voltage overhead distribution line, except there was only one conductor.
Click to expand...

Is that what they call SWER-Single Wire Earth Return ?
 
JoeStillman said:
But this is rare.
Click to expand...
It is rare to see as utility supplied service. It is fairly common as control voltage on machines or control systems, and is occasionally seen for limited power as a separately derived system. Say you have 480/277 as the main power but need limited 120 volts for a convenience receptacle - you may just derive 120 only from appropriate sized transformer.
 
John120/240 said:
Is that what they call SWER-Single Wire Earth Return ?
Click to expand...

I hope this wasn't commonplace. Had a fairgrounds where primary side of two transformers on poles were never attached to system ground, only to ground wire ran down pole. We didn't know of this condition until one hot summer day and a dry summer the poles were smoking as higher than previous currents were traveling down the ground wire along the pole to earth because of increased Air conditioner use. At the time, out of curiosity I took the back of my hand towards the ground wire to see how hot it may have been and if I remember correctly I think I felt a tingle which after I thought about it could have been a very bad situation.
Still here!
 
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