Required Safety devices NEC 2020 code Powerwall installation

[CrazyRabbit]

i'm in fort worth tx. two years ago, fort worth required disconnect switch inside the garage and outside by the meter for my enphase solar installation, which is connected to the meter base.

I have 320 amp service. in the garage i have a 200 amp loads panel for non backed up circuits and a 200 amp panel powering my house for backed up circuits.

fast forward to today, I'm having powerwalls installed, what safety devices are required for this installation?

NEC 2020 code, section 230.85, requires emergency disconnect/service disconnect located outside by the meter. would it be acceptable to have only one of my panels on on a disconnect switch or should both be on said switch. tesla only want to put one panel on the disconnect switch, which in the event of a fire and the switch is utilized by the fire department my other panel would still be powered and they would have no knowledge of this. so should tesla put both panels (non backed up and gateway/backed up panel) on a disconnect switch/breaker (meeting 230.85 requirements) or just the gateway/backup panel?

My existing solar will be connected to the 400 amp generation panel removing both my 100 amp disconnect switches. will the tesla optional remote disable switch be sufficient to shutdown my solar? or is other equipment required.

i'm afraid my system needs 100 or more disconnect switches, lol.

 

[Vines]

i'm in fort worth tx. two years ago, fort worth required disconnect switch inside the garage and outside by the meter for my enphase solar installation, which is connected to the meter base.

I have 320 amp service. in the garage i have a 200 amp loads panel for non backed up circuits and a 200 amp panel powering my house for backed up circuits.

fast forward to today, I'm having powerwalls installed, what safety devices are required for this installation?

NEC 2020 code, section 230.85, requires emergency disconnect/service disconnect located outside by the meter. would it be acceptable to have only one of my panels on on a disconnect switch or should both be on said switch. tesla only want to put one panel on the disconnect switch, which in the event of a fire and the switch is utilized by the fire department my other panel would still be powered and they would have no knowledge of this. so should tesla put both panels (non backed up and gateway/backed up panel) on a disconnect switch/breaker (meeting 230.85 requirements) or just the gateway/backup panel?

My existing solar will be connected to the 400 amp generation panel removing both my 100 amp disconnect switches. will the tesla optional remote disable switch be sufficient to shutdown my solar? or is other equipment required.

i'm afraid my system needs 100 or more disconnect switches, lol.

The properly labeled main breakers in your main service panel (assuming no separate structures) ensure compliance with the 230.85 I think.

I am not able to speak to your local requirements, but I would recommend putting in the remote disconnect switch near the main service. This way, you open the main disconnects and activate the battery disconnect (in any order) and all power to the ESS, PV and Subapnels is eliminated. This is compliant with the requirements of 706.15.A as well.

Also if there was some fire in the control circuit or nearby, it is a normally closed circuit. Any damage to the wire would trigger the emergency battery disconnect function when the circuit opened.

 

[Vines]

The properly labeled main breakers in your main service panel (assuming no separate structures) ensure compliance with the 230.85 I think.

I am not able to speak to your local requirements, but I would recommend putting in the remote disconnect switch near the main service. This way, you open the main disconnects and activate the battery disconnect (in any order) and all power to the ESS, PV and Subapnels is eliminated. This is compliant with the requirements of 706.15.A as well.

Also if there was some fire in the control circuit or nearby, it is a normally closed circuit. Any damage to the wire would trigger the emergency battery disconnect function when the circuit opened.

There may be additional local AHJ disconnect requirements that I don't see yet, as the description of your installation was pretty basic. No guarantee I didn't miss something without some more information.

 

[CrazyRabbit]

diagram doesn't say anything about optional emergency disconnect button. i know fort worth says there must be provisions to shut down the system outside by the meter and in the garage since that is where my loads panels are. what is the purpose of the ac disconnect, emergency disconnect/service disconnect?
i combined most of my loads into a 80 circuit panel, loads calc for panel/house is 175 amps, using mike holt toolbox app.

 

[CrazyRabbit]

USER INPUTS​

A. General Lighting/Receptacles:

Living Area in Sq. Ft.:

3000sq. ft.

Small Appliance Circuits: 3 Circuits

Laundry Circuit(s): 1 Circuit(s)

B. Fixed Appliances and Equipment:

Dishwasher(s), 120V:1Unit(s),15 Amperes

Disposal(s), 120V:1Unit(s),10 Amperes

Jacuzzi Tub(s), 120V:1Unit(s),1200 VA

Microwave(s), 120V:1Unit(s),1100 VA

Water Heater(s), 240V:1Unit(s),4500 VA

Well Pump(s), 240V: 1Unit(s),3 Horsepower

Electric Dryer(s), 240V:1Unit(s),5000 VA

Electric Cooktops(s), 240V:1Unit(s),7200 VAOven Single(s), 240V:1Unit(s),5000 VA

C. Cooling/Heating Load(s):

Cooling Load: AC/Condenser
46A and Fan 4A, 240V

Heating Load: Heat
28800 VA and Fan 4A, 240V

COPPER RESULTS​

1. Service Disconnect Rating: 175A
2. Service Conductor Size:
1/0 AWG, rated 150A at 75°C
3. Service Neutral Conductor Size: 6 AWG, rated 65A at 75°C
4. Supply-Side Bonding Jumper: 6 AWG
5. Raceway Size: 2 Inch

ALUMINUM RESULTS​

1. Service Disconnect Rating: 175A
2. Service Conductor Size: 3/0 AWGAL, rated 155A at 75°C
3. Service Neutral Conductor Size: 4 AWGAL, rated 65A at 75°C
4. Supply-Side Bonding Jumper: 4 AWGAL
5. Raceway Size: 2 Inch

Service Calculation[220.82(B)]

A. General Lighting/Receptacles:

Living Area: 3000 x 3 VA = 9000VA

Small Appliance Circuits: 1,500 VA x 3 = 4500VA

Laundry Circuit(s): 1,500 VA x 1 = 1500

B. Fixed Appliances and Equipment

Dishwasher(s), 120V:1Unit(s) x 15 Amperes x 120V =1800VA

Disposal(s), 120V:1Unit(s) x 10 Amperes x 120V =1200VA

Jacuzzi Tub(s), 120V:1Unit(s) x 1200 VA = 1200 VA

Microwave(s), 120V:1Unit(s) x 1100 VA = 1100 VA

Water Heater(s), 240V:1Unit(s) x 4500 VA = 4500 VA

Well Pump(s), 240V:1Unit(s) x 3 Horsepower = 4080VA



1Unit(s), 5000VA



Electric Cooktops(s), 240V:1Unit(s), 7200VA

Oven Single(s), 240V:1Unit(s), 5000VA

Subtotal: 46080VA
First 10,000 VA at 100%: 10000

Remainder 36080 VA at 40% = 14432 VA

Subtotal Demand Load: 24432 VA

C. Cooling/Heating Load(s) [220.82(C)]:

Cooling Load at 100%: 240V x (46A + 4 A) = 12000 VA


[Omit Per 220.60]

Heating Load at 65%: [28800VA +(240V x 4 A)] x 65% = 12896 VA
Heating Load at 40%: [28800VA +(240V x 4 A)] x 40% = 3968 VA

Cooling/Heating Demand Load: 16864 VA

Total Service Demand Load:

Service Demand VA Load (A, B, and C):41296 VA

Service Load in Amperes: 172A ( 41296 VA/240V)

NOTES:​

1. Service Disconnect Rating [240.4 and 240.6(A)]

Service disconnect sized must have an ampacity of at least 172A

Service Disconnect Rating: 175A

2. Service Conductor Size [310.15(B)(7) and Table 310.15(B)(16)]

Service conductor sized to 83% of 175A service disconnect rating.

175x 83% = 145.25A

3. Service Neutral Conductor Size [220.61 and Table 310.15(B)(16)]

A. General Lighting, Small Appliance, and Laundry VA Load: [220.42]

General Lighting: 3000 sq. ft. x 3 VA = 9000 VA

Small Appliance Circuits: 1,500 VA x 3 = 4500 VA

Laundry Circuit(s): 1,500 VA x 1 = 1500 VA

First 3,000 VA at 100% = 3000 VA

Remainder, 12000 VA at 35% = 4200 VA

General Lighting, Small Appliance, and Laundry Demand Load: 7200

B. Appliance(s) VA Load:​

Dishwasher(s), 120V:1Unit(s) x 15 Amperes

Total: 5300 VA x 75% = 3975 VA, 220.53

Disposal(s), 120V:1Unit(s) x 10 Amperes

Total: 5300 VA x 75% = 3975 VA, 220.53

Jacuzzi Tub(s), 120V:1Unit(s) x 1200 VA

Total: 5300 VA x 75% = 3975 VA, 220.53

Microwave(s), 120V:1Unit(s) x 1100 VA

Total: 5300 VA x 75% = 3975 VA, 220.53

C. Dryer(s) VA Load [220.60]​

Neutral Demand Load [220.61(B)]​

5000VA x 70% = 3500 VA, 220.54

D. Cooking Equipment VA Load [220.61] and Table 220.55​

Neutral Demand Load [220.61(B)]​

0 VA x 70% = 0 VA, 220.55

Neutral VA Demand Load(A, B, C, and D)​

7200 VA + 3975 VA + 3500 VA + 0 VA = 14675 VA

Neutral Load in Amperes:

61A ( 14675 VA/240V)

4. Supply-side Bonding Jumper Size [250.102(C)]​

Supply-side bonding jumper sized to the service conductor size.

5. Raceway Size [Chapter 9, Table 1]​

Based on a raceway at 40% fill, with an equipment grounding conductor.

 

[BGbreeder]

Wow! Lots of details. On your diagram, one small question from an electrical neophyte; should the neutral be bonded in the Tesla gateway, rather than the 400A panel?

All the best,

BG

 

[CrazyRabbit]

The properly labeled main breakers in your main service panel (assuming no separate structures) ensure compliance with the 230.85 I think.
...
Also if there was some fire in the control circuit or nearby, it is a normally closed circuit. Any damage to the wire would trigger the emergency battery disconnect function when the circuit opened.

the main breakers are in garage, 230.85 requires disconnect by meter.
from my experience, fire causes all wiring to short out. fire will cause the battery disconnect wires to short out, rendering the NC switch useless and the powerwalls still on. it would have been much better to have a EOL resistor to properly detect tampering of wires OC or SC. perhaps it does.
regardless they need to place a emergency shutdown switch outside and inside the garage.

Why we use End of Line (EOL) Resistor in Fire and Gas System ? - Inst Tools

The End-of-Line Resistor used in fire alarm systems may look as same as a Terminating Resistor, however the function of the End-of-Line Resistor is completely different.

instrumentationtools.com

Wow! Lots of details. On your diagram, one small question from an electrical neophyte; should the neutral be bonded in the Tesla gateway, rather than the 400A panel?

All the best,

BG

Neutral is only to be bonded at the first means of disconnect, period. so would that be the AC disconnect switch?

 

[wwhitney]

Wow! Lots of details. On your diagram, one small question from an electrical neophyte; should the neutral be bonded in the Tesla gateway, rather than the 400A panel?

The OP has essentially two services, as does any 2x200A service. In which case there is a neutral-ground bond (main bonding jumper) in each service disconnect. In the diagram drawn, they would be in the "existing distribution panel" and the "ac disconnect", the two boxes on the left next to the meter.

Cheers, Wayne

 

[wwhitney]

My comments:

- Installing an exterior disconnect for one of the 200A service panels and not the other would be crazy, certainly not in accordance with the spirit of (2020) NEC 230.85.

Also, I assume the "AC disconnect" shown is the exterior disconnect. Having that outside and configured as the service disconnect means that your other service disconnect must be outside next to it, independent of 230.85. So your existing 200A panel (on the left of the diagram) would need to be supplied by a new exterior 200A service disconnect with a 4-wire feeder, all the GEC connections would need to move to that new disconnect, and grounds and neutrals would need to be separated in your existing 200A panel.

- The only way you can put a 400A generation panel (rather one with more than 200A of generation) behind the 200A Backup Gateway is if the Gateway is configured as a PCS to monitor that feeder (section 6 on the diagram) and limit the current on it to 200A (or is it 160A?), or 180A (or maybe 144A) if any of those feeders are 4/0 Al rather than 3/0 Cu. Presumably Tesla plans to do that.

- With multiple services and the house loads split among them, any copper feeders protected at 200A need to be 3/0 Cu, not 2/0 Cu; any 2/0 Cu would need to be protected at 175A. 4/0 Al can be protected at 200A, but it only has a 180A ampacity. Just a general warning, since you cut off the feeder details.

Cheers, Wayne

 

[CrazyRabbit]

My comments:
... since you cut off the feeder details.

Cheers, Wayne

 

[wwhitney]

Further comments:

- The main breaker in the Gateway is redundant. Now if the N-G bond and GECs are moved from the AC disconnect to the Gateway, and the exterior AC disconnect is labeled "Emergency Disconnect--Not Service Equipment", then the main breaker in the Gateway would be required. And then if the Gateway is next to the other 200A service panel, a similar Emergency Disconnect (230.85) for it could be installed outside, and the other 200A service panel would not require any change to its GECs and N-G bond

- If there is just one dwelling unit on site, and the other existing 200A service panel supplies some loads to that dwelling unit (vs, say, being dedicated to a second dwelling unit, or to a detached wood shop), then conductors (4), (6), and (7) are wrong. The allowance to protect 2/0 Cu at 200A only applies when a 200A service is serving all of and only one dwelling unit. Absent that, 2/0 Cu has to be protected at 175A, and 3/0 Cu is required for 200A OCPD.

The existing conductors to that other 200A panel also bear checking; the only way they could be 2/0 Cu is if they are serving all of and only a second dwelling unit.

Cheers, Wayne

 

[Vines]

diagram doesn't say anything about optional emergency disconnect button. i know fort worth says there must be provisions to shut down the system outside by the meter and in the garage since that is where my loads panels are. what is the purpose of the ac disconnect, emergency disconnect/service disconnect?
i combined most of my loads into a 80 circuit panel, loads calc for panel/house is 175 amps, using mike holt toolbox app.

View attachment 809131

My comments
I have to say, I don't totally understand your system, or maybe I just need my coffee to kick in, since I slept in and am on vacation. I was up late at a concert last night.

Around here, your 400A combo panel with meter would be located on an exterior wall, so the 2 main breakers inside it are the service disconnects. However, I do not see the main breakers in the service panel explicitly drawn, though they are shown in text above the service panel.

If there are 2x200 main breakers there at the meter, why is the disconnect fused, unless that is all Tesla installs? Unless this is just a 400A meter can without any disconnects at the meter? Something doesn't make sense to me in the diagram compared to the description.

What is the method of compliance for the Tesla design for an exterior means to shutdown the ESS system if there is no ESS emergency disconnect, are the Powerwalls or 400A subpanel outside and readily accessible?

If the (fused?) 200A bladed AC disconnect was outside, and electrically between the TEG and the 400A subpanel, then it would accomplish ESS and PV rapid shutdown. Then it's the same as any other house, turn off the main breakers and then turn off the 200A Safety Switch.

I don't see why to use the forked design at all, and if the TEG and 400A subpanel were colocated, I would feed the 200A essential loads subpanel from the 400A subpanel. It could be that this would max the slots in the 400A subpanel, but would eliminate the need for the 200A main breaker in the essential loads subpanel and the 400A subpanel.

I am going to drink some coffee and keep watching this thread as I am sure this will make more sense.

 

[wwhitney]

Unless this is just a 400A meter can without any disconnects at the meter?

Yes, that is what the diagram shows. Not so common in CA but common enough in the rest of the country and likely the default in some areas.

Cheers, Wayne

 

[Vines]

Yes, that is what the diagram shows. Not so common in CA but common enough in the rest of the country and likely the default in some areas.

Cheers, Wayne

It's just not what the text says just above it. Ok now this makes more sense.

 

[wwhitney]

It's just not what the text says just above it. Ok now this makes more sense.

Ahh, you must be interpreting "(E) 2x200A MAIN SERVICE PANEL" as "(2x200A) service panel" singular. While I'm interpreting it as "2 x (200A MAIN SERVICE PANEL)" plural. Since that is what the diagram shows by not showing any OCPD in the meter base. And by showing the N-G bond on one side downstream of the meter base.

On the other hand, that means the "TO (E) DISTRIBUTION PANEL (LEFT)" is mislabeled or at least misleading, it should be "TO (E) SERVICE PANEL (LEFT)".

All of my comments have been based on the above understanding; if the diagram is wrong, obviously the comments may change. The OP could clarify whether I am correct in inferring there is no OCPD outside in the meter base, and the service disconnects are currently the (2) main breakers in the (2) 200A garage panels (which should be side by side).

Cheers, Wayne

 

[Vines]

Ahh, you must be interpreting "(E) 2x200A MAIN SERVICE PANEL" as "(2x200A) service panel" singular. While I'm interpreting it as "2 x (200A MAIN SERVICE PANEL)" plural. Since that is what the diagram shows by not showing any OCPD in the meter base. And by showing the N-G bond on one side downstream of the meter base.

On the other hand, that means the "TO (E) DISTRIBUTION PANEL (LEFT)" is mislabeled or at least misleading, it should be "TO (E) SERVICE PANEL (LEFT)".

All of my comments have been based on the above understanding; if the diagram is wrong, obviously the comments may change. The OP could clarify whether I am correct in inferring there is no OCPD outside in the meter base, and the service disconnects are currently the (2) main breakers in the (2) 200A garage panels (which should be side by side).

Cheers, Wayne

Yes, I put too much stock in what I am used to seeing here in California and forget that in other places CSED aren't common.

 

[CrazyRabbit]

doesn't table 310.12 allow 2/0 for service conductor....

 

[wwhitney]

doesn't table 310.12 allow 2/0 for service conductor....

Note the requirement about "supplying the entire load associated with a one-family dwelling" in the subsections of 300.12. That is why my comments were predicated upon the load of a one-family dwelling being split between the two 200A panels. Then 2/0 Cu is too small for a 200A feeder/service.

But if all the load of one dwelling is on one panel, that panel can be supplied by 2/0 Cu protected at 200A. The other panel would not get the same leniency, unless it also supplied all the load of a different dwelling unit.

Cheers, Wayne

 

[CrazyRabbit]

..
The OP could clarify whether I am correct in inferring there is no OCPD outside in the meter base, and the service disconnects are currently the (2) main breakers in the (2) 200A garage panels (which should be side by side).

Cheers, Wayne

correct, no ocpd outside. just a meter can, first ocpd is in the two 200A panels.

 

[CrazyRabbit]

doesn't the powerwalls and solar still power the house with the proposed system? gateway thinks utility is down and powerwalls and solar keep working. utility worker is safe, but not the fireman. solar is hot as well as house...
or am i wrong? i've seen tesla installs just like this on the net...