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

[Energy Electric]

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.

 

[ActionDave]

You still have a bad neutral somewhere most likely. Power company guys do not always diagnose their side of the electrical system correctly.
"So when I put my meter on his conductors" is too vague of a description of where you are taking your voltage readings from to give more precise assistance.

What kind of contracting are you semi retired from. Forum rules mandate that we don't allow threads giving electrical advice to non electricians.

 

[jaggedben]

Definitely a bad neutral.

If the microwave is backed up I'm a bit surprised the Tesla gateway isn't disconnecting from the grid at that voltage out of range. It could mean the bad neutral is on the branch circuit with the microwave.

 

[ptonsparky]

Does the Tesla unit care what the L-N voltage is after it leaves ?

Classic bad neutral symptoms .

 

[Energy Electric]

You still have a bad neutral somewhere most likely. Power company guys do not always diagnose their side of the electrical system correctly.
"So when I put my meter on his conductors" is too vague of a description of where you are taking your voltage readings from to give more precise assistance.

What kind of contracting are you semi retired from. Forum rules mandate that we don't allow threads giving electrical advice to non electricians.

I'm a semi retired Electrical contractor, At the main meter panel all my readings are normal

 

[Energy Electric]

Definitely a bad neutral.

If the microwave is backed up I'm a bit surprised the Tesla gateway isn't disconnecting from the grid at that voltage out of range. It could mean the bad neutral is on the branch circuit with the microwave.

Well this is a weird situation, meter is at the street the house is up the hill, approx 500' two splice boxes, one of the splice boxes I have already re spliced the the connections, second splice box all the connections were done by a high voltage contractor and they all look really good, not to say it isn't but that will be my last spot. From the last splice box it goes to the garage 200amp load center with a 200amp main breaker, from there it goes through his Tesla power wall and back to the houses load center. So yes there is a lot going on here and yes I have gone through all the connection points to make sure everything is tight. All of this happened all of a sudden , and yes his tesla power wall goes haywire when the voltage appears not to be stable. He is going to call PG&E again and have them check the neutral connection behind the meter section which they didn't do the first time they came out.

 

[Energy Electric]

Does the Tesla unit care what the L-N voltage is after it leaves ?

Classic bad neutral symptoms .

Yes the Tesla power wall goes crazy when the voltage is unstable.

 

[retirede]

At the main meter panel all my readings are normal

This would imply that the compromised neutral is downstream of the meter. Not a utility problem.

 

[electrofelon]

Well this is a weird situation, meter is at the street the house is up the hill, approx 500' two splice boxes, one of the splice boxes.

Do you know if it's direct buried or in conduit? Could be a bad neutral underground.

 

[qcroanoke]

Do you know if it's direct buried or in conduit? Could be a bad neutral underground.

There are contractors out there with the equipment to find a fault underground if you determine that's where it is.

 

[LarryFine]

At the main meter panel all my readings are normal

Then you need to do point-by-point voltage readings until you find the bad wire or connection.

Fall-of-potential tests may also help, looking for voltage between points that should have none.

Everything that I have read so far suggests a bad connection in the shared neutral of a MWBC.

 

[Hv&Lv]

This would imply that the compromised neutral is downstream of the meter. Not a utility problem.

I’m so glad someone said that…

 

[jaggedben]

Does the Tesla unit care what the L-N voltage is after it leaves ?

Classic bad neutral symptoms .

Yes the Tesla power wall goes crazy when the voltage is unstable.

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.

 

[texie]

As I always say when this type of post comes up the EC better learn quick and find the weak neutral soon or the magic smoke will arrive soon. Weak/open neutrals can have expensive consequences in this day and age.

 

[qcroanoke]

If it wasn't 500 ft between the service disconnect at the meter and the 200 amp panel I'd run a temporary neutral and see if the problem goes away. If it doesnt at least you'd know where it ain't. Lol

 

[ptonsparky]

Finding the location of a faulted underground is easy with the right equipment.

 

[Hv&Lv]

Finding the location of a faulted underground is easy with the right equipment.

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”

Dynatel 573A Earth Fault/Cable Fault Locator

The Dynatel 573A is a portable, battery-powered tone set that detects and pinpoints health and conductor faults, and locates the path of buried or underground (UG) cables. It will indicate the presence of dangerous voltage on a...

www.atecorp.com

 

[kwired]

Well this is a weird situation, meter is at the street the house is up the hill, approx 500' two splice boxes, one of the splice boxes I have already re spliced the the connections, second splice box all the connections were done by a high voltage contractor and they all look really good, not to say it isn't but that will be my last spot. From the last splice box it goes to the garage 200amp load center with a 200amp main breaker, from there it goes through his Tesla power wall and back to the houses load center. So yes there is a lot going on here and yes I have gone through all the connection points to make sure everything is tight. All of this happened all of a sudden , and yes his tesla power wall goes haywire when the voltage appears not to be stable. He is going to call PG&E again and have them check the neutral connection behind the meter section which they didn't do the first time they came out.

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.

 

[Energy Electric]

Do you know if it's direct buried or in conduit? Could be a bad neutral underground.

Ok this what we have found so far, everything is good at the meter panel PG&E came back and verified, I have then re spliced all three conductors at the firs box, went to the second box and untaped the connection there and it was good, no burnt insulation the wire looks great. the next thing that I dis was take a reading with my meter, I made a very small hole in the insulation on each of the hot wires A and B phase and one leg to neutral I'm getting 116v and on the other i'm getting 130volts. so I went down to the first box and I did the same thing and at each phase I was getting 124v to neutral each. So that telling me that somewhere between the first and second box which is in conduit mind you they must have nicked the neutral wire when they where pulling it in 20+years ago..

 

[Energy Electric]

As I always say when this type of post comes up the EC better learn quick and find the weak neutral soon or the magic smoke will arrive soon. Weak/open neutrals can have expensive consequences in this day and age.

Well if you have reading the post sent out i'm doing my best to try and figure it out from point A to Point B which in turn I have determined that they must have nicked the neutral wire when they pulled it in 20 + years ago