You gotta be kidding me. Electricians won't add a Tesla wall connector on the backup side of ESS

[wwhitney]

is there a way to see the imbalance between the two legs

Get yourself a Kil-A-Watt or the like, plug it into a receptacle for voltage reading, and make sure it doesn't change (much) as you turn on loads. If turning on a load (which would be on the opposite leg) ever makes the voltage go higher on the Kil-A-Watt, that's a pretty definite sign of a neutral problem.

Cheers, Wayne

 

[CrazyRabbit]

Put a amp meter on your ground and you will see a few amps flowing. I can turn off my mains and still see a few amps. My ground is better then the utility!
So current is flowing thru the neutral to my ground.
is there a maximum allowed current be for utility souls fix this?
My neutral wire is same gage as L1/L2

 

[wwhitney]

Put a amp meter on your ground and you will see a few amps flowing. I can turn off my mains and still see a few amps.

Are you in an area with metallic water mains and water laterals? The most likely reason for the current on your GEC while your main breaker is off is that a neighbor on the same transformer has a compromised neutral, but since the neutral is earthed at both your houses to the metallic water service, the neighbor's lowest impedance neutral return path is through the water main and your neutral connection (along with everyone else on the same transformer).

Cheers, Wayne

 

[Vines]

A few comments:

- Vines likely had a marginal neutral to begin with, possibly already with some voltage imbalance. Then during the stress test, the imbalance of the loads on the two legs must have been greater than previously seen, causing enough voltage imbalance to damage equipment.

- Connection to earth doesn't matter for low voltage (i.e. < 1000V) questions like this.

- With an intact neutral, 120V L-N loads on opposite legs work as expected (and if there's any current imbalance between the draw on the two legs, the neutral will carry that current.) When the neutral is compromised, then you end up with a series circuit, supplied with 240V, with the parallel 120V loads on one leg in series with the parallel 120V loads on the other leg (and the current through the two series loads has to be equal, there is no neutral to carry the unbalanced current). So the voltage drop across the two series loads will divide in proportion to their impedances. If they happen to be equal, you won't notice the missing neutral. But if one leg has more impedance (which if the individual loads were all the same would mean fewer of them are turned on, since the individual loads are in parallel), it will see more voltage drop, often sufficiently in excess of 120V to damage equipment.

Cheers, Wayne

During the 10 minutes or so that we had no neutral wire, it took out the following appliances:
Old HP plotter
Brother Laserjet printer
Clothes Dryer
Bose Wave Radio
Computer surround system
Clock on a natural gas stove
4 powerstrips at least smoked right in front of our faces.
Several wall switches or the fixtures

PGE guy that came out told us our load was imbalanced, but we were pulling 25 kW 35 kW peak from a 200A service, mostly with 3 electric dryers and my car, all of them 240v loads.

 

[holeydonut]

During the 10 minutes or so that we had no neutral wire, it took out the following appliances:
Old HP plotter
Brother Laserjet printer
Clothes Dryer
Bose Wave Radio
Computer surround system
Clock on a natural gas stove
4 powerstrips at least smoked right in front of our faces.
Several wall switches or the fixtures

PGE guy that came out told us our load was imbalanced, but we were pulling 25 kW 35 kW peak from a 200A service, mostly with 3 electric dryers and my car, all of them 240v loads.

Dude... does homeowners insurance cover that type of damage? I wonder what would have happened if you had Powerwalls at the time of that test.

I can't wait to get an EV...

 

[CrazyRabbit]

Are you in an area with metallic water mains and water laterals? The most likely reason for the current on your GEC while your main breaker is off is that a neighbor on the same transformer has a compromised neutral, but since the neutral is earthed at both your houses to the metallic water service, the neighbor's lowest impedance neutral return path is through the water main and your neutral connection (along with everyone else on the same transformer).

Cheers, Wayne

My connection to water main is thru black polymer pipe, but house pipe is copper. My transformer impedance was low, approved for 20+ powerwalls, which was measured L1-N, N-L2.
Neutrals on our grid do float a bit, do you see neutrals on three phase transmission lines... theoretically neutral current becomes zero..

 

[CrazyRabbit]

Dude... does homeowners insurance cover that type of damage? I wonder what would have happened if you had Powerwalls at the time of that test.

I can't wait to get an EV...

I’m going to guess powerwall has a auto transformer. Which would handle the neutral current.

 

[Vines]

Dude... does homeowners insurance cover that type of damage? I wonder what would have happened if you had Powerwalls at the time of that test.

I can't wait to get an EV...

I have only very basic coverage, so I pay this stuff out of pocket.

Wife took it as an excuse to get newer nicer stuff, lol. I was happy to be rid of some of it, which were power hogs anyway. The printers were especially big offenders, and now I have a nice desktop 11x17 inkjet printer. If we pulled 25 kW with the Powerwalls most of it would come from the Powerwalls so our service would no be stressed. Also we are getting a 400A service upgrade as part of the project.

 

[CrazyRabbit]

Auto transformer can create the neutral leg. Passive device, so should work with powerwall off. Try turning off powerwalls and measure your neutral current to them.

 

[DanB2]

I have 2 ACs on 2 Powerwalls in a full home backup setup. I agree that they would run down the batteries pretty quickly but to me, the real benefit is that if there is an outage during the day (such as a brownout in the summer here in SoCal), my 11 kW solar system can comfortably run both AC units and charge the batteries during the day. With 27 kWh in the batteries, I can run one of the ACs intermittently at night and still have a good reserve in the morning (as long as the summer is coming up).