Adamjamma
Senior Member
- Location
- Jamaica and london
Since it is pvc I would really like to know how the bond was made... I know how I would achieve it in the Caribbean... due to 5he building techniques... but it is against the codes there..lol...
Missing neutral
- Thread starter Fmkehoe
- Start date
- Status
Fmkehoe
Senior Member
- Location
- Cornwall ny USA
- Occupation
- Inspector
Will do. I’ll go by and shutter-bug away. I’d like to pull the meter, but can’t.
ptonsparky
Tom
- Occupation
- EC - retired
My best GUESS is that they have a common metallic water pipe with neighboring homes. OPs home has an electric water heater that has an EG installed back to the neutral bar in the panel. Neutral current is flowing along this EG to the water line, to the neighbor(s) then on their neutral(s) back to the transformer. Note: Guess, also in my case known as a SEWAG. Another SEWAG could be there is another wire from the rod into the panel that he has missed.
Sounds like the OP looked things over pretty closely so we will wait
Kwire mentioned other possibilities.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Adamjamma
Senior Member
- Location
- Jamaica and london
in caribbean the homes are concrete with rebar tied in such a way that you actually have a ground cage almost as good as a faraday cage around you, due to the way they put the foundation rebar in, tying to the columns and the reinforcements, the various beams, the concrete decks... all the way up to the roof...
Using my ground tester, I have actually seen homes there that measured a lower ground reference value when the ground rod was disconnected from the rebar in the walls... not much but... One reason why I am looking forward to the course in the spring on ground rod tests...lol... to see if somehow the way I was taught to test ground rods is wrong or I am doing it wrong..lol...
But ten homes I have tested you could disconnect the ground rods and only use the rebar in the concrete as a ground and be just fine. The Ze number was lower on the tester without the ground rod bond to the rebar bond... lol.
Of course, I am not well trained and am trying to learn more so am always willing to be told I am doing something wrong as long as the person telling me I am wrong shows me the right way...lol
Using my ground tester, I have actually seen homes there that measured a lower ground reference value when the ground rod was disconnected from the rebar in the walls... not much but... One reason why I am looking forward to the course in the spring on ground rod tests...lol... to see if somehow the way I was taught to test ground rods is wrong or I am doing it wrong..lol...
But ten homes I have tested you could disconnect the ground rods and only use the rebar in the concrete as a ground and be just fine. The Ze number was lower on the tester without the ground rod bond to the rebar bond... lol.
Of course, I am not well trained and am trying to learn more so am always willing to be told I am doing something wrong as long as the person telling me I am wrong shows me the right way...lol
Fmkehoe
Senior Member
- Location
- Cornwall ny USA
- Occupation
- Inspector
So here are the two hot legs coming into the panel.
You can see the bare ground wire coming in from outside.
And you can see where it attaches to the grounding/neutral buss.
Also, I checked out the water meter, there is no grounding wire on the plumbing pipes.
Attachments
ptonsparky
Tom
- Occupation
- EC - retired
Do you have an electric water heater or any other equipment that is in contact with the plumbing? You may not see a 6 bare directly connected to the WP.
Is there a common metallic water piping system in the neighborhood? Clamp your amp meter around the water line as it leaves the house. Do the same for any other piping system. Some current is normal on these but you should be able to see a significant change in current as you cycle 120v loads in the house.
Do you have an amp clamp meter?
Fmkehoe
Senior Member
- Location
- Cornwall ny USA
- Occupation
- Inspector
ptonsparky
Tom
- Occupation
- EC - retired
JFletcher
Senior Member
- Location
- Williamsburg, VA
at this point I would have to guess that there is an underground bond from the ground rod at the panel to the poco ground, or an overlooked or hidden bond to metal water pipe.
ptonsparky
Tom
- Occupation
- EC - retired
Its there somewhere and may take a shovel to find.
OP. Can you access the POCO neutral? Have you amp clamped it? Time to call the POCO and open things up. Then again if everything is working.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
151115-2359 EST
Open all breakers except one circuit. Load that circuit with at least one 1500 W spacer heater. This will provide about a 10 A load. That 10 A has to flow thru something acting as the neutral.
But before doing this put a screwdriver in the earth somewhere away the home and where you do not expect much ground current to flow. From this earth probe run a test lead into the house near the main panel. Use an insulated wire, size unimportant. Use a high impedance meter.
With no load on in the house, except possibly a low wattage bulb near the main panel, Measure voltage between each hot incoming line, and the earth reference. Also between earth and the neutral bus. Measure hot line to hot line voltage. Measurement should be to 1/10 V.
Repeat these measurements with the 1500 W 120 V heater as the only load.
From this data we can learn a lot.
Depending upon these results the next step may be to measure magnetic fields to see were the neutral current is going.
.
Open all breakers except one circuit. Load that circuit with at least one 1500 W spacer heater. This will provide about a 10 A load. That 10 A has to flow thru something acting as the neutral.
But before doing this put a screwdriver in the earth somewhere away the home and where you do not expect much ground current to flow. From this earth probe run a test lead into the house near the main panel. Use an insulated wire, size unimportant. Use a high impedance meter.
With no load on in the house, except possibly a low wattage bulb near the main panel, Measure voltage between each hot incoming line, and the earth reference. Also between earth and the neutral bus. Measure hot line to hot line voltage. Measurement should be to 1/10 V.
Repeat these measurements with the 1500 W 120 V heater as the only load.
From this data we can learn a lot.
Depending upon these results the next step may be to measure magnetic fields to see were the neutral current is going.
.
Fmkehoe
Senior Member
- Location
- Cornwall ny USA
- Occupation
- Inspector
Natural gas, no bond on there either.
Well, it's worked fine since 1990, maybe I could just run a single neutral to the meter. :happysad: But I can't get in without breaking the seal, or call poco.
mjf
Senior Member
Is this house located in Cornwall, NY?
If so, you are required to hold a Rockland County Electrical license (or work for a licensed holder) to perform electrical work.
no disrespect intended, but from your profile, you don't seem to qualify.
Best of luck!
If so, you are required to hold a Rockland County Electrical license (or work for a licensed holder) to perform electrical work.
no disrespect intended, but from your profile, you don't seem to qualify.
Best of luck!
ptonsparky
Tom
- Occupation
- EC - retired
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
EGC to a furnace could possibly be carrying neutral current, though NG usually has isolating fitting somewhere near the point of emerging from underground and/or at metering equipment.
Licensing requirements don't change the physics here.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
181117-1130 EST
I believe I previously mentioned that you can use a coil and sensitive voltmeter to search for unbalanced AC 60 Hz current.
This coil should be about 2000 turns on a 1/2" diameter or square bobbin. #32 wire would work. Shunt this with a 1 ufd Mylar capacitor to reduce higher frequencies. Use a meter that resolves 10 microvolts. This is distance sensitive from the current,
At the moment I read about 50 mV on phase A, 30 mV on phase B, 15 mV on neutral. My water line from the street was about 0.8 mV. All of these readings have substantial error relative to each other. But it is clear not much neutral current is on my water line. The water line reading into house was down in the noise around 0.02 mV.
.
I believe I previously mentioned that you can use a coil and sensitive voltmeter to search for unbalanced AC 60 Hz current.
This coil should be about 2000 turns on a 1/2" diameter or square bobbin. #32 wire would work. Shunt this with a 1 ufd Mylar capacitor to reduce higher frequencies. Use a meter that resolves 10 microvolts. This is distance sensitive from the current,
At the moment I read about 50 mV on phase A, 30 mV on phase B, 15 mV on neutral. My water line from the street was about 0.8 mV. All of these readings have substantial error relative to each other. But it is clear not much neutral current is on my water line. The water line reading into house was down in the noise around 0.02 mV.
.
Fmkehoe
Senior Member
- Location
- Cornwall ny USA
- Occupation
- Inspector
Fmkehoe
Senior Member
- Location
- Cornwall ny USA
- Occupation
- Inspector
Don’t remember. If I go by I’ll check it out.
- Status