Tesla surprises with a $4800 bill on existing $5300 install contract

[SMAlset]

If it weren’t for all the loss of lives and property, you could almost say the wildfires would be a good thing for the advancement of solar and battery back up. Of course other areas of the country have been affected by hurricanes, tornado damage, bad winter storms that have kicked out their power for periods of time too.

With covid, SIP and WFH more people are dependent on spending more hours at home and needed to stay connected and comfortable in their homes.

 

[wwhitney]

This is the breaker in question, you can see its (2) 100A breakers tied by a common trip. Either 100A tripping trips the whole thing, within the limits of the UL listing.

OK, I text chatted with Schneider Electric today, it took 3 different people to get the full story. Here it is:

- HOM2200 has a single 200A trip mechanism.
- The bus in the SC2040M200C is a single 200A bus.
- The wire bending space restricts distribution wiring to #1 or smaller (for breakers with perpendicular to bus entries).
- Heat rise testing restricts 2 position breakers to 100A or less (do not use HOM2125).
- The product was UL listed before the 4 position breaker and subfeed lugs were available, so it has never been tested with them.
- The product is sufficiently mature there are no plans to invest further development time on it and test the combination.

So my take away is that the HOML225 should work fine with the SC2040M200C, but as it is not a tested combination, it is not approved to use them together.

Cheers, Wayne

 

[Vines]

Good investigation, and good to know Wayne!

Much better than the way it was explained to me, by someone who probably assumed.

This puts it in the grey area of it works but its not listed for it. Good to know its not due to a wimpy bus. Thanks for correcting me.

 

[wwhitney]

As to the question of tripping the 100A breaker in my scenario, it depends on the CT location and the load on the non backup side. You are partially correct that this is an issue. In this case, likely the additional CT could only go around about 20A worth of non backup load to offset, depending on actual draw, actual load at the home, and actual PV generation.

I did a little more research on this, your idea of having a generation panel with more than 80A of inverter output current but fed by only a 100A feeder would obviously work in most circumstances without tripping the 100A feeder breaker, but there is an NEC section it would violate. 705.60/705.65 requires that the feeder between the electrical service and the inverters be sized for the full 125% of the inverter output current. So to comply with that you could only put, say, (2) Powerwalls and 32A of PV inverter output current on a single 100A feeder.

Another bummer, because it is otherwise a pretty reasonable idea. I had one more idea on how to get a 200A feeder out of the SC2040M200C, but it's a bit unusual and I'm not sure if it's NEC compliant. Namely, use (2) pairs of parallel 1/0 conductors for the 200A feeder. Each pair lands in a HOML225, and the two HOML225 are on opposite sides of the HOM2200 main breaker, the same distance from it. [They could be right next to it, unless more separation is need to keep the wire terminations for interfering with each other.]

1/0 is the smallest size allowed to parallel. It's one size larger than the maximum #1 branch conductor listed, but since the HOML225 uses an angled entry wire lug providing more wire bending space, that should be OK. The current should divide equally, so it's only 100A per "branch circuit breaker". [And even it doesn't, it's still almost a factor of two less current per bus stab than using a single HOML225.]

Cheers, Wayne

 

[Vines]

The powerwalls can only backfeed into panels with CTs, though the NEC does not recognize this.

This is why my comment about 20A worth of CT in the non backup panel.

GW2 has some magic around this that will be released soon.

As to the parallel 1/0, I like how you are thinking and it sounds safe, but maybe not totally complaint, as the breaker isn't listed on the sticker, and the #1 maximum.

 

[Vines]

This is one solution to the NEC backfeed issues. Will be interesting to see what the inspectors think.

 

[wwhitney]

The powerwalls can only backfeed into panels with CTs, though the NEC does not recognize this.

This is why my comment about 20A worth of CT in the non backup panel.

Ah, I guess you are proposing a 100A feeder from the meter main to the Backup Gateway, but >100A wiring from the Backup Gateway to the generation panel and to the backed up load panel. So you only need to limit the CTs in the non-backup panel to limit the maximum export on the 100A portion of the feeder. I didn't get the mixed wiring sizes at first.

So that would work in practice, although it is not currently recognized by the NEC and you have to consider the full inverter output current of each Powerwall. But the 2020 NEC has some language about "Power Control Systems", and once that version is adopted, if Tesla gets the proper listing on the Powerwalls, then it would be doable.

Cheers, Wayne

 

[Vines]

Wayne, I went to Schneider advanced support, and tried to get them to take our money. @wwhitney

I was asking if they would explore relisting this CSED to accept this 200A 4 pole connection.

The rep basically said the same he said to you, that they had no interest even with our money. He also said he thought it would fail rise of heat testing with the 4 pole 200A connection.

 

[wwhitney]

Very interesting, thanks for the update.

He also said he thought it would fail rise of heat testing with the 4 pole 200A connection.

I really don't see how it would be any different from have (2) double pole 100A breakers next to one another. Does he know something we don't? Is there some physics reason the single column bus arrangement is worse at dissipating heat than a double column bus arrangement, even when the heat is generated within a single column?

Cheers, Wayne

 

[Vines]

Very interesting, thanks for the update.

I really don't see how it would be any different from have (2) double pole 100A breakers next to one another. Does he know something we don't? Is there some physics reason the single column bus arrangement is worse at dissipating heat than a double column bus arrangement, even when the heat is generated within a single column?

Cheers, Wayne

The HOM2200BB is one single breaker, so it may perform differently under heat load.

Likely they just want to make us but new service panels, they get nothing out of working with us in this way, as we would buy less service panels.

 

[pgrovetom1]

Its now been a month and my 3 Powerwalls and all 4 panels are just sitting there not yet wired. I struggled through the crazy billing and Tesla had a local contractor contact me to sort out their mess. They just could not figure out how to get the wiring to work out. I spoke to the local contractor who decided he needed to come over to understand how to best arrange the wiring to and from my main panel and the new equipment wall. We worked out a scheme that wasn't too bad but he decided a new main panel with meter and disconnect only made sense to both fit on the PG&E side for the meter and provide a splice area where breakers would have been. Then to use wiring troughs flying over top to wire main feed from disconnect and spliced service wires ( 200A house, 100A house, and 50A pool) to the top of my wall and then to the backup and non backup panels. So I extended my wall toward the existing service by 7 inches and dug a trench to reroute the solar directly to the generation panel. We will reroute wires that didn't need to go up my service pole such as the solar and pumps on the ground. That minimizes the splicing needed in the new panel empty space.

After he and I worked out this plan, he sent a cost to Tesla. Then Tesla removed the 2 items from my contract that were wrong, the solar meter and PW pad. That reduced the cost by about $1500 and Tesla charged me about the same for the new panel, permit changes and accepted the labor due to their bungling. That means my new contract is roughly the same. So now its been almost 2 weeks and Tesla says they are waiting for purchasing to send a contract to the local contractor. This project has been a real nightmare and its surprising Tesla can install any complex job due to their incompetence and horrible internal communication and coordination. I was happy with their manager who took over and arranged getting things right so far.

So it just sits looking like this waiting for completion.

 

[sorka]

So do I have one of the cheaper center fed panels? Mines the CGBT40M2F4:

On the south side of the 200 amp disconnect, I've got:

Double Pole:
90 (sub panel)
30
50
50
20
20

Single Pole:
20
20
20
20
20

That's 620 amps of single pole (roughly 310 per leg).

On the north side of the 200 amp disconnect, there are 10 15 single pole breakers and one double pole 90.

That's 1/2 of what the south side has. Something doesn't seem right there. Although the north side only has 14 slots while the south has 25 slots.

Does that "branch finger rating" of 100 amps mean 100 amps max on either side of the main?

The other confusing thing is the bigger breakers on on the very ends of the bus rather than being close to the center. Wouldn't you want the biggest loads distributed evenly on both sides and as close to the main disconnect as possible?

 

[Vines]

@sorka
Yes that is a cheaper center fed panel. It cannot do whole home backup easily, You are limited to 100A of max draw through any single breaker. You could do a 100A circuit to the Gateway, and leave one of those 90A subfeeds on the bus and relocate everything else to the backup side, as long as you had enough power wall resources. (100% rule)

Alternately (120% rule), downsize the main to 175A or 150A and do a total of 70A or 95A of PV Plus Powerwalls backfed into the distribution bus with that same 100A max breaker, and move any number of breakers onto the backup side in the new subpanel. The calculated load in the backup circuit should not exceed the branch circuit breaker rating protecting your backup circuit.

The reason heavy loads go at the end of the bus to reduce heat buildup near the main CB. Don't worry about the distribution of them, if there's no smoke, no excess heat and no breakers are tripping you are better off leaving the worry to the experts.

@pgrovetom1 glad to hear Tesla is making things right so you can get up and running, even if not at your speed.

 

[sorka]

@sorka
Yes that is a cheaper center fed panel. It cannot do whole home backup easily, You are limited to 100A of max draw through any single breaker. You could do a 100A circuit to the Gateway, and leave one of those 90A subfeeds on the bus and relocate everything else to the backup side, as long as you had enough power wall resources. (100% rule)

Alternately (120% rule), downsize the main to 175A or 150A and do a total of 70A or 95A of PV Plus Powerwalls backfed into the distribution bus with that same 100A max breaker, and move any number of breakers onto the backup side in the new subpanel. The calculated load in the backup circuit should not exceed the branch circuit breaker rating protecting your backup circuit.

The reason heavy loads go at the end of the bus to reduce heat buildup near the main CB. Don't worry about the distribution of them, if there's no smoke, no excess heat and no breakers are tripping you are better off leaving the worry to the experts.

@pgrovetom1 glad to hear Tesla is making things right so you can get up and running, even if not at your speed.

Thanks for the quick reply. So the limit is 100 amps per breaker, not 100 amps for the entire bus on that side of the main service? What's to prevent a total load of more than 100 amps on one side split among multiple breakers? Will the service disconnect trip when it exceeds 100 amps on a single side?

FYI, I'm not adding PWs right now. Just solar. But having seen the topic, it got me wondering what I'd need to do to add them. If I did so, I'd want to go 3 or 4 so I'd be more inclined to just upgrade the whole panel.

 

[Vines]

The limit is 100A per breaker location, the panel is listed for 200A. If overloaded the Main CB will trip. The main breaker protects the 200A bus, in case multiple breakers need more power at once than the main breaker can handle it will trip..

If you plan to add 3 or more powerwalls, it makes sense to replace it. If you are just doing PV it is sufficient.

I wouldn't worry if its getting overloaded unless there is an issue like I pointed out above. If you have ever reset a breaker more than once or twice, and especially if the main breaker has ever needed resetting.

 

[sorka]

The limit is 100A per breaker location, the panel is listed for 200A. If overloaded the Main CB will trip. The main breaker protects the 200A bus, in case multiple breakers need more power at once than the main breaker can handle it will trip..

If you plan to add 3 or more powerwalls, it makes sense to replace it. If you are just doing PV it is sufficient.

I wouldn't worry if its getting overloaded unless there is an issue like I pointed out above. If you have ever reset a breaker more than once or twice, and especially if the main breaker has ever needed resetting.

Thanks so this isn't a bus bar limitation of 100 amps on each side of the main service breaker but instead a limit on the size of the breaker itself? Could you not use a 4 pole breaker?

 

[Vines]

Thanks so this isn't a bus bar limitation of 100 amps on each side of the main service breaker but instead a limit on the size of the breaker itself? Could you not use a 4 pole breaker?

You could put a 200A 4 pole on the bus, and it may fit. However if you are the last electrician in the MSP and made a non-compliant 200A connection any fire will be blamed on you 100%.

It says pretty clearly 100A max. That being said, I have seen worse decisions.

One "Dead front" we pulled off almost lived up to its namesake. Someone made a line side tap into the unprotected line conductors with a wood screw into the aluminum wire, then taped it with electrical tape. Its a good thing it didn't kill the guy who removed that cover.

 

[sorka]

You could put a 200A 4 pole on the bus, and it may fit. However if you are the last electrician in the MSP and made a non-compliant 200A connection any fire will be blamed on you 100%.

It says pretty clearly 100A max. That being said, I have seen worse decisions.

One "Dead front" we pulled off almost lived up to its namesake. Someone made a line side tap into the unprotected line conductors with a wood screw into the aluminum wire, then taped it with electrical tape. Its a good thing it didn't kill the guy who removed that cover.

Thanks. And I'm not actually going to do that. It was just a question to help make sure I was understanding what you had said previously.

 

[Vines]

Thanks. And I'm not actually going to do that. It was just a question to help make sure I was understanding what you had said previously.

Sorry if I seemed combative, its a subject that comes up a lot. I see this variously being dangerous to costly for the customer but is also the (bad) reason why a customer might choose a cheaper installer. The cheap installer just know the AJH doesn't know better, slap some subfeed lugs in there and go.

With us at the cutting edge of PV and ESS installations we have to self regulate and not give our industry a bad name. It only takes a couple fires, someone doing something stupid before the hand of regulation slaps us down.

 

[wwhitney]

I looked at Eaton's catalog of CH products, I didn't see any 4 position branch breakers or subfeed lugs.

Cheers, Wayne