High current on neutral with a balanced load

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jhardy13

Member
Location
Joplin Missouri
Occupation
Industrial Engineering student
I would think with a DC circuit you just have a straight line. Reduced in amplitude because of the resistance. Intermittent would cause changes but again only in amplitude. My SEWAG.
Okay following that logic, if I knew the normal amplitude of a device on an unimpeded circuit, could I determine the impedance of another circuit with that same device based on the amplitude? Impedance might not be the correct term here. Please correct me if I am wrong. Hopefully you understand what I'm asking here.
 
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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
201031-1106 EDT

jhardy13:

In your main panel there are normally two bus bars aside from the hots. One should be the EGC bar, and the other the neutral bar. These two bars are tied together by a very low impedance path, and must be. At the present moment I read 0.7 millivolts between my two bars with a Fluke 27 meter. But I also read 0.2 mV with the two meter leads just shorted together in that general region, and this one turn loop may not be seeing the same magnetic field as when I make the voltage drop measurement between the two bus bars. The basic point is that those two bars should be at essentially the same voltage.

When you turn off your main breaker in the main panel, then there should be no current flow from your power transformer back thru your neutral and EGC bus bars to the transformer center tap. You can check that you see no hot wire current. Assuming that hot wire current is zero, then look for what neutral or EGC wires have current flow. Look for and determine which wires show current flow. This current, if it exists, comes from somewhere else.

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Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
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EC - retired
Okay following that logic, if I knew the normal amplitude of a device on an unimpeded circuit, could I determine the impedance of another circuit with that same device based on the amplitude? Impedance might not be the correct term here. Please correct me if I am wrong. Hopefully you understand what I'm asking here.
Not sure if I understand, but I would think Ohms Law is your answer. Resistance is normally associated with DC, impedance with AC. If you know I,E,&R, in one circuit and I changes in the second, you should be able to determine R, everything else being the same.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
J. H., you could temporarily disconnect the incoming coax and measure the voltage between the cable's shield and your grounding block. Be careful and expect some voltage once separated; you may even get arcing.

I believe the cable trunk has 60 vac on it for in-line distribution equipment, but I don't know whether that voltage is filtered or blocked from the customer drops. Your cable tech department may be able to help here.

It may help you to draw out a diagram of the various interconnections between the house and the outside world. Include in this the power and cable drops, along with water or any other conductive, metallic pathways.

The guys who seem to be giving you grief are trying to help. It's as frustrating to us as to you when symptoms change over time. The bottom line is that a logical progression of elimination should pinpoint the cause(s).
 
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