240 volt 1 phase, voltage rises to 146v when they turn on the microwave or any other appliance.

[Energy Electric]

Agreed.
I picked two of these on eBay about 8 years ago for $250. They work fantastic. Only time they struggle is when it’s in a splice that’s bad but wrapped in 273 layers of electrical tape, or conduit.

Basically anything “open air”

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This situation the wires are in conduit and at least 2 + feet underground and was installed 20+ years ago

 

[Energy Electric]

So it sounds like you have about 500 feet of possible places for this conductor to have failed.

Also note that long runs of small conductors (not saying yours are undersized) can fool you into thinking you have a bad neutral if load is pretty unbalanced. I ran into it on a golf course one time where they had a maintenance shop about 2000 feet away from where it received supply. Not much for load in that little building but still too much voltage drop on what was only maybe 2 AWG aluminum conductors over that kind of distance.

Ok Thanks, On this situation they ran 3/0 copper which I said to him that they should have ran 250 copper for at least 300ft then down size at the second splice box.

 

[Energy Electric]

If you would be more specific about what happens when it 'goes crazy' that could help narrow down the location of the problem.

If the neutral issue is upstream of the Tesla Gateway then I would expect the Gateway to disconnect from the grid when either L-N voltage is outside of about 135V and 108V. And then, if there's only one issue, the Powerwalls should operate fine off grid. But then the line side voltage could go back to normal without load, so the Gateway would reconnect to the grid after a minute or a few minutes, and the cycle would repeat. If this describes it 'going crazy' then your issue is likely between the meter and the Tesla Gateway.

If the neutral issue is between the Powerwalls and the loads I wouldn't expect the Powerwall to necessarily be able to notice.

Thank you , I have figured it out that neutral wire is damaged between the first and second splice box.

 

[electrofelon]

Ok Thanks, On this situation they ran 3/0 copper which I said to him that they should have ran 250 copper for at least 300ft then down size at the second splice box.

oh wow they ran copper for this? A nick in copper is unlikely to corrode thru like happens with AL. Are you sure you maintained the same loading during each test? IF the loading changed then the voltage measurements wouldnt be consistent.

 

[kwired]

Thank you , I have figured it out that neutral wire is damaged between the first and second splice box.

Though sounds like what you did has likely determined what segment is bad I'd maybe confirm by either placing some sort of temporary jumper around the suspected bad conductor to see if that solves the symptoms or even connect meter across suspected bad conductor (may need to use some extension cords as lead extensions) and check for voltage across the suspected bad segment of conductor.

Temp jumper need not be too large of a conductor if load is rather balanced , just needs to be big enough to carry the imbalance current, extension cord(s) with alligator clip test lead adapters for each end may very well be what I would have as equipment on the truck to attempt to do this with.

 

[electrofelon]

Though sounds like what you did has likely determined what segment is bad I'd maybe confirm by either placing some sort of temporary jumper around the suspected bad conductor to see if that solves the symptoms or even connect meter across suspected bad conductor (may need to use some extension cords as lead extensions) and check for voltage across the suspected bad segment of conductor.

Temp jumper need not be too large of a conductor if load is rather balanced , just needs to be big enough to carry the imbalance current, extension cord(s) with alligator clip test lead adapters for each end may very well be what I would have as equipment on the truck to attempt to do this with.

yeah gunna want to make sure currents stay the same for each measurement. Maybe two people with meters and phones to measure at same time, or control what is going on at the house and plug an electric heater or something large.

 

[qcroanoke]

Though sounds like what you did has likely determined what segment is bad I'd maybe confirm by either placing some sort of temporary jumper around the suspected bad conductor to see if that solves the symptoms or even connect meter across suspected bad conductor (may need to use some extension cords as lead extensions) and check for voltage across the suspected bad segment of conductor.

Temp jumper need not be too large of a conductor if load is rather balanced , just needs to be big enough to carry the imbalance current, extension cord(s) with alligator clip test lead adapters for each end may very well be what I would have as equipment on the truck to attempt to do this with.

If the microwave starts playing pretty and your voltages even out I'd say you've found it.

 

[ptonsparky]

Cu has much less of a tendency to corrode in half due to a nick in the insulation. Hopefully some one didn't bury or pull in a splice.

 

[qcroanoke]

I wonder if the raceway is broken somewhere? That would take away pull 1 out and pull 1 in....

 

[ptonsparky]

oh wow they ran copper for this? A nick in copper is unlikely to corrode thru like happens with AL. Are you sure you maintained the same loading during each test? IF the loading changed then the voltage measurements wouldnt be consistent.

Relying on chance to get an imbalance isn't the best method for sure.

Adding a consistent load on one leg is the best.

 

[electrofelon]

Cu has much less of a tendency to corrode in half due to a nick in the insulation. Hopefully some one didn't bury or pull in a splice.

Yeah seattle city light uses uncovered concentric neutral cables for their 25.5KV UG distribution, in flooded vaults, wet conduits and everything. CU would last a long time exposed.

 

[ptonsparky]

I thought I'd hit a tree root with my shovel until I felt the copper braid on the buried primary. Exited ditch in record time. Prior to Diggers hotline.

 

[jaggedben]

A good option here would be to set the Tesla system to stay off-grid, via its app. Then hook up a known load on the supply side of it to do your testing.

 

[kwired]

Yeah seattle city light uses uncovered concentric neutral cables for their 25.5KV UG distribution, in flooded vaults, wet conduits and everything. CU would last a long time exposed.

I've encountered 1940's-1950's underground copper with rubber insulation still in use. Some cases the neutral was bare solid conductor and wasn't showing any serious deterioration signs.

I once encountered an underground run from house to a garage. They did use a conduit but pulled overhead aluminum "triplex" through it with the bare ACSR neutral. I did pull it out and replace it, the neutral was mostly gone other than the steel strand, but IIRC it was broke in a few places as well. Probably been 20-25 years ago so not every detail is that clear anymore.

 

[TKsparky]

I have a client that has a 1 phase 240 volt service that has a 200amp main breaker at the meter panel and two underground pull boxes to his house to a 200amp main panel with a 200amp main breaker. he also has 3 tesla power wall back up units with batteries. As of yesterday all of a sudden his lights are flickering and his Microwave is running really slow. He had PG&E come out and check there side and they said that he has a bad neutral between the main breaker and his 200amp subpanel.
I respliced his neutral wire in one of his pull boxes and he still is having a issue with his microwave. So when i put my meter on his conductors it reads 122v on 1 phase and 130v on the second phase, when he turns on his drill press that 2 phase rises to 148volt ? I have tighten up every connection between his 200amp sub panel and his tesla power wall panel and still getting the same results. I have tighten up all of his grounds and neutral connections. Is there any one out there that can help me with this situation.

I suspect it is due to a direct buried (aluminum) feeder. It sounds like the neutral has been compromised. It could also happen in conduit, but rarely. Can you check voltage at the two splice boxes? That will help narrow it down. How are the Tesla power cells wired in. Can you bypass them?

 

[qcroanoke]

I suspect it is due to a direct buried (aluminum) feeder. It sounds like the neutral has been compromised. It could also happen in conduit, but rarely. Can you check voltage at the two splice boxes? That will help narrow it down. How are the Tesla power cells wired in. Can you bypass them?

From post 22,
Ok Thanks, On this situation they ran 3/0 copper which I said to him that they should have ran 250 copper for at least 300ft then down size at the second splice box.

 

[Strathead]

Thank you , I have figured it out that neutral wire is damaged between the first and second splice box.

I haven't seen this mentioned, I may have missed it. I doubt a nick in the wire would cause the problem you describe. It is possible, but the problem is either a high resistance, or an open in the neutral. It would take some fairly high loading for a merely corroded copper wire to have a resistance high enough to cause the voltage fluctuations you are describing.

 

[Frank DuVal]

Ok Thanks, On this situation they ran 3/0 copper which I said to him that they should have ran 250 copper for at least 300ft then down size at the second splice box.

Yes! I ran 4/0 copper to my garage for 150 Amp feed at 400 feet! 4 grand at the time, my price for the copper wire, but still cheaper than paying the power company to run underground primary and set a transformer. That was a 15K estimate 15 years ago. Due to small load of a garage/workshop, even though I "loaded" my load worksheet! I should have said it was a second residence...

I'm not sure why to downsize the conductor at the second splice box, it they were symmetrically placed. Now if the last run was much shorter then maybe.

 

[Energy Electric]

oh wow they ran copper for this? A nick in copper is unlikely to corrode thru like happens with AL. Are you sure you maintained the same loading during each test? IF the loading changed then the voltage measurements wouldnt be consistent.

Well everyone guess what! we found another underground splice box and yes the neutral connection was corroded and melted thru the splice connector. How we found it was we had a spare conduit running from box to box and I was going to run a sperate wire thru it to check for the voltage from point A to point B and we could only get our fish tape in 100+ ft on each side and it was not moving so we stretched out the fish tap going both direction and guess what another splice box buried in the ground. Anyway I want to thank everyone for there input and trying to trouble shoot this .

 

[qcroanoke]

Well everyone guess what! we found another underground splice box and yes the neutral connection was corroded and melted thru the splice connector. How we found it was we had a spare conduit running from box to box and I was going to run a sperate wire thru it to check for the voltage from point A to point B and we could only get our fish tape in 100+ ft on each side and it was not moving so we stretched out the fish tap going both direction and guess what another splice box buried in the ground. Anyway I want to thank everyone for there input and trying to trouble shoot this .

Buried j box? Who would thought.....