Prep for Charging Circuit(s) / Panel Question

[airbish]

Another Panel/Circuit Question. We just got our 90D VIN early this week and are prepping for home charging.

I am certainly going to engage a qualified electrician to do this, but I like to be educated first..

Here's our Panel setup (after having to re-trace (and re-label) mostly everything due to the horrendous documentation by previous owner/electricians).

- 200Amp to Main Panel. Two-Sub Panels (and a 'Sub sub'.)

- Main Panel (200Amp in / 30 Slot): Dual 70Amp to Sub-A, Dual 60Amp to Sub-B, Dual 70Amp to 2 AC Units, Dual 30Amp to Clothes Dryer, Dual 40Amp to Wall Oven, Dual 25Amp to 3rd AC. 2 x single 20Amp, 10 x Dual 15Amp. One open single 'slot'. Yeah it seems pretty full.

- Sub-A (70Amp in / 12 Slot): 5 x dual 20Amp, 7 Open Slots

- Sub-B (60Amp in / 12 Slot): 60Amp Dual to Pool Equipment Box + 2 x 20Amp, 6 x 15Amp, 2 open slots.

- Pool Equipment Box: (60Amp in / 8 Slot) 1 x Quad? 20Amp, 2 x Dual 20Amp, 2 x single 20Amp driving: Jandy CPU/Controller, 2HP Main pump (single speed, going to go to variable...but will still be 2hp), 3/4HP Water Feature Pump, Cleaner Boost Pump (not sure what HP). I haven't done the math on what all this really draws.

(An aside question I have is why the Sub-B is only on a 60Amp when it has it's own 60Amp 'sub' to the pool equipment box and the additional circuits. That doesn't make any sense to me. Especially when there is a 70Amp sub with a lighter load. But I'm certainly no expert.

Can anyone weigh in for me what the best path would be here. For the foreseeable future a single 14-50 (or equivalently setup HPWC) would be fine for me. My commute is short (and we have J1772s at the office). Any road trips I would supercharge or use CHAdeMO. We may likely end up with a second EV in the future but not for now.

Thoughts? I'd love to have some education (and options) before I call the electrician and pay an ignorance tax.

Btw, I'd love (I think) to be able to have a second dedicated main on an EV night rate plan...but that may be intrusive/expensive to get done...and it doesn't seem popular/possible with Georgia Power. For now just focused on getting the 50Amps run to the garage for a 14-50 or WPWC. If I can get more out there (for future use), great.

Thanks very much!

Photos attached if it helps.

 

[aesculus]

You might want to contact your utility first and ask them to do a load calc on your meter. I have a 200 amp main panel with a ton of sub panels too but the utility told me I rarely go over 130 amps. And if I charged after 11pm to 7am, even at 80 amps, I would never be over the rated load of my panel. Your situation may be different.

Then the other questions are where do you want to put the plug and how far is it way from any panel and can you get access to it? The likelihood of using one of you existing panels depends on available slots, total capacity of the panel and what size wire is feeding it. Probably none of your sub panels can probably take on the additional 14-50 without a major wire/breaker change, and one panel does not even have any room. Can't see the breaker size on Sub A or Sub B but an electrician would have to add all of that up for you plus know the types of devices connected or potentially connected to determine if they are upgradable or not. Your main panel does not show any place for a double pole breaker to add an additional sub panel unless you could move one of the breakers to another sub and open up two slots.

Bottom line from my perspective is I would ask the utility for the load calc first and then hire an electrician for an assessment.

 

[airbish]

Thanks aesculus,

All good and valid. The utility load calc sounds like a great first step. In the meantime I'm going to start mapping out all the specific devices and related loads.

Sub-A is a 70Amp breaker off the main panel. SubB is a 60Amp breaker (with a 60Amp breaker off that to the pool panel. I still don't get that.

My gut is that it could squeeze into Sub-A...but again...I'm guessing. There is slot space there...and the handful of 20Amps in there now are fairly light with the exception of a full size fridge. Small Under Cabinet Fridge, Small undercabinet drawer dishwasher (rarely gets used), microwave, warming drawer (rarely used), a cooktop vent/fan hood, and several additional 20amp runs for a small number kitchen/island outlets and under/over-cabinet lighting. I don't know what large built-in fridge draws (easy to look up) but it's on a 20Amp. So.. I guess I just don't see anywhere near a full 70Amps coming through all that. Enough to draw an extra 40 with some reasonable load on the rest? I don't know. If we need to shuffle a little, I don't think it will be crazy. The 3 panels are all adjacent on the same wall....and I have to believe there is headroom overall on the 200 main.

The panels are in the basement but in very close proximity to the garage. The basement closet where the panels are is adjacent to the wall where the garage starts (on the next floor up). The washer and dryer are directly above the panel and on a wall that is adjacent to the garage. It's a 3-car and we would like to put the charge ports in between the 2nd and 3rd bays. I'm guessing no more than a 30' run overall, probably less.

Thanks again. Will make the call to GA Power / SoCo for the load calc. (maybe I can see it in the portal somewhere).

 

[aesculus]

Access makes all the difference in the world. If they can easily pull new conductors you can do a lot of things, and the panels themselves are peanuts if you need to swap them.

 

[BrokerDon]

We had a similar main / sub panel configuration and the Tesla recommended electrician used a load calc and pulled permits and got our HPWC installed right next to our 100A sub panel which was adjoining our 200A main panel in our 2006 built tract home. Has worked perfectly for 10 months now, usually charging at 60A with a couple of 80A fast charges too.

Seems crazy to me the builder filled the 200A main panel and 100A sub panel leaving ZERO empty breaker spaces... instead of installing a 400A panel... especially since our utility (SCE) confirmed a 400A panel upgrade was both easy and free by only pulling another wire through the existing underground conduit from their transformer. I'm planning on upgrading our main panel to 400A if we add solar so we can get the 30% tax credit on the panel upgrade.

 

[airbish]

Thanks! Definitely going to do the load calc.

In the meantime... I get detailed kWh reports from the GA Power portal. Trying to convert those to Amps to get a average daily Amp draw. (I totally understand needing to know peak draw vs average...but that should give me a starting point).

We have one of those 90's-built unnecessarily large, inefficient homes (with a pool, 2 kids, etc.). So we are sort of a poster-child for excessive energy usage at the moment. Working hard to fix that. Gone almost all LED, redoing insulation/windows, Nests, upgrading to variable speed pool pump, upgrading to high Seer AC units, etc. HOA won't allow solar (that I am aware of)...otherwise I would consider it.

Currently we average around 3,000 kWh/mo in cool/shoulder months (8-9 months) and 4,500-5,000 kWh during the hot(lanta) months. Yeah..I know.... Working on it.

Is there a way to use that information to get to a ballpark Amp draw? I've gone through some of the online calcs (like: http://www.rapidtables.com/calc/electric/kW_to_Amp_Calculator.htm)...but I'm not sure what options to select for phase / voltage / power factor to accurately relate it back to the info I'm getting from the PoCo. I could do more research and get to it...but thought I'd ask.

Thanks again.

 

[aesculus]

Your biggest load is undoubtedly AC. If you have anything you can schedule (pool, drying clothes) to keep out of the late night - early AM window then you can set the Tesla to start charging when everything else is off. Then your total load will not be a factor. That's assuming that your AC load and the Tesla does not put you over the top. Where I live it can be 100F + during the day but by 10AM or so the AC units are usually off or come on for only a few minutes at a time. Again the peak loading, or even better a time of day loading profile, will help you. Don't worry about anything except for watts at this stage. You are just looking to see if you can find a window for charging (unless you have to be able to charge 24/7).

 

[AWDtsla]

Thanks! Definitely going to do the load calc.

In the meantime... I get detailed kWh reports from the GA Power portal. Trying to convert those to Amps to get a average daily Amp draw. (I totally understand needing to know peak draw vs average...but that should give me a starting point).

We have one of those 90's-built unnecessarily large, inefficient homes (with a pool, 2 kids, etc.). So we are sort of a poster-child for excessive energy usage at the moment. Working hard to fix that. Gone almost all LED, redoing insulation/windows, Nests, upgrading to variable speed pool pump, upgrading to high Seer AC units, etc. HOA won't allow solar (that I am aware of)...otherwise I would consider it.

Currently we average around 3,000 kWh/mo in cool/shoulder months (8-9 months) and 4,500-5,000 kWh during the hot(lanta) months. Yeah..I know.... Working on it.

Is there a way to use that information to get to a ballpark Amp draw? I've gone through some of the online calcs (like: http://www.rapidtables.com/calc/electric/kW_to_Amp_Calculator.htm)...but I'm not sure what options to select for phase / voltage / power factor to accurately relate it back to the info I'm getting from the PoCo. I could do more research and get to it...but thought I'd ask.

Thanks again.

It kind of sounds like you got the cheapest possible AC units, and they are possibly malfunctioning as well. Around here 2-3 electric bills would pay to have them replaced with something modern.

kWh draw does not have a 1:1 with ampacity needed. I would add up the minimum circuit ampacity for your AC's and other high-draw items.

 

[airbish]

Well I wouldn't say they are the cheapest, but they are old...and I do not believe they are malfunctioning. With that said, I have quotes for all new 18 Seer systems (like I gave to the new owner of my old house) ready to go in.

Going to do the load calc for sure but I'm confident at this point that I don't need to sweat the additional 50amp.

Thanks.

 

[ABCCBA]

@airbish - How long of a commute do you have each day? That will determine how much and how fast you need to charge the battery at home. Then, based on the minimum amount of time needed to recharge the battery, you can determine the amperage charging rate. With you only having a 200A service to the house, two A/C units, a swimming pool and then your standard appliance load, you will be pushing the limits of your service during the summer time when your house is fully loaded and you have the car charging at +50A. JMHO.

Go to your Georgia Power Smart Meter and look at the electronic readings. There will be a KWh reading and a KW reading, amongst the several that scroll. Look at the KW reading. It should be XX.xxx or a similar format. That is your demand, or highest rate of usage. From that, it can easily be determined what the highest amperage is at the 'peak' usage, by dividing the demand by 0.240.

How far is your garage from your electric meter? If it is relatively close, you could look at upgrading your meter panel to dual breaker, 320A panel and have GPC upgrade the service drop to 320A. Then, you could have one of the Main Breakers be a 200A and feed all your existing services exactly as they are. The second breaker could be installed and run to feed a 100A panel for the garage and your EV charger.

Just a little input and thought. But, it all depends on your current load on the 200A service, charging rate you need to recharge you car for daily use and the distance from your electric meter to the garage.

 

[AWDtsla]

Well I wouldn't say they are the cheapest, but they are old...and I do not believe they are malfunctioning. With that said, I have quotes for all new 18 Seer systems (like I gave to the new owner of my old house) ready to go in.

That's probably because that's what the local HVAC contractors stock. I would aim for something over 25 SEER, hopefully with inverter control. It frees up ampacity in your load center, in addition to just saving a ton of cash in energy

 

[ddimit]

The most immediate and the biggest return on your investment will be a variable speed ( note, not 2 Speed) pool pump. Its a pretty easy change out and some utilities offer rebates to offset the cost. You will go from a standard 1 hp pump drawing 12+ amps over a 8 hour window down to 1-2 amps on low speed running over a longer filtering window.

 

[airbish]

The most immediate and the biggest return on your investment will be a variable speed ( note, not 2 Speed) pool pump. Its a pretty easy change out and some utilities offer rebates to offset the cost. You will go from a standard 1 hp pump drawing 12+ amps over a 8 hour window down to 1-2 amps on low speed running over a longer filtering window.

Agreed completely. Ordered one two days ago. Going from 2hp single-speed 8-12 hours a day (with cleaner and spillover) to 2hp variable. Expecting a ~70% reduction. Ran the hard calcs the other day, don't recall the numbers. Traveling for work this week but will have it in when I get back. Wasy install. I need all the projects I can get to fill the wait time. That's right I need to check to see of GA Power rebates on those. They should.

 

[airbish]

That's probably because that's what the local HVAC contractors stock. I would aim for something over 25 SEER, hopefully with inverter control. It frees up ampacity in your load center, in addition to just saving a ton of cash in energy

Hmmm... I did Trane XV80 variable speed furnace/ah's and XR18 units at the last house and I thought those where pretty solid. I'll have to look into that some more. We are looking at doing additional attic insulation (maybe radiantguard as well) and replacing most of the windows. But yeah, AC is what gets us (other then the pool pump, which I'm dealing with now.) Will have to look at that. Lennox?

 

[airbish]

@airbish - How long of a commute do you have each day? That will determine how much and how fast you need to charge the battery at home. Then, based on the minimum amount of time needed to recharge the battery, you can determine the amperage charging rate. With you only having a 200A service to the house, two A/C units, a swimming pool and then your standard appliance load, you will be pushing the limits of your service during the summer time when your house is fully loaded and you have the car charging at +50A. JMHO.

Go to your Georgia Power Smart Meter and look at the electronic readings. There will be a KWh reading and a KW reading, amongst the several that scroll. Look at the KW reading. It should be XX.xxx or a similar format. That is your demand, or highest rate of usage. From that, it can easily be determined what the highest amperage is at the 'peak' usage, by dividing the demand by 0.240.

How far is your garage from your electric meter? If it is relatively close, you could look at upgrading your meter panel to dual breaker, 320A panel and have GPC upgrade the service drop to 320A. Then, you could have one of the Main Breakers be a 200A and feed all your existing services exactly as they are. The second breaker could be installed and run to feed a 100A panel for the garage and your EV charger.

Just a little input and thought. But, it all depends on your current load on the 200A service, charging rate you need to recharge you car for daily use and the distance from your electric meter to the garage.

 

[airbish]

@airbish - How long of a commute do you have each day? That will determine how much and how fast you need to charge the battery at home. Then, based on the minimum amount of time needed to recharge the battery, you can determine the amperage charging rate. With you only having a 200A service to the house, two A/C units, a swimming pool and then your standard appliance load, you will be pushing the limits of your service during the summer time when your house is fully loaded and you have the car charging at +50A. JMHO.

Go to your Georgia Power Smart Meter and look at the electronic readings. There will be a KWh reading and a KW reading, amongst the several that scroll. Look at the KW reading. It should be XX.xxx or a similar format. That is your demand, or highest rate of usage. From that, it can easily be determined what the highest amperage is at the 'peak' usage, by dividing the demand by 0.240.

How far is your garage from your electric meter? If it is relatively close, you could look at upgrading your meter panel to dual breaker, 320A panel and have GPC upgrade the service drop to 320A. Then, you could have one of the Main Breakers be a 200A and feed all your existing services exactly as they are. The second breaker could be installed and run to feed a 100A panel for the garage and your EV charger.

Just a little input and thought. But, it all depends on your current load on the 200A service, charging rate you need to recharge you car for daily use and the distance from your electric meter to the garage.

Good info. Thank you. Will look at the meter. And will check into the upgraded main.

My typical daily commute is short...4 miles or so...and we have 1772s at office and will probably put a 100Amp HPWC or two in...teslas are adding up. But there are some days that I need to hop around...Charlotte, B'Ham, Greenville, etc. In reality, I don't need anything more than a 50Amp...I just like to be prepared.

Run from Panel to Garage is short. Panel is in basement but adjacent to garage and an easy punch through. 30' most I'm guessing.

Run from from Meter is similar, it's just on the outside wall from main panel and on the same external wall as garage. About as easy as it gets I think.

Thanks again.

 

[ABCCBA]

@airbish Shown is my current setup. I have a HPWC for the Tesla and a 14-50 with a 'rig' that I made for the Volvo. I have 80A for the Telsa and 50A for any future EV(s).

Good info. Thank you. Will look at the meter. And will check into the upgraded main.

My typical daily commute is short...4 miles or so...and we have 1772s at office and will probably put a 100Amp HPWC or two in...teslas are adding up. But there are some days that I need to hop around...Charlotte, B'Ham, Greenville, etc. In reality, I don't need anything more than a 50Amp...I just like to be prepared.

Run from Panel to Garage is short. Panel is in basement but adjacent to garage and an easy punch through. 30' most I'm guessing.

Run from from Meter is similar, it's just on the outside wall from main panel and on the same external wall as garage. About as easy as it gets I think.

Thanks again.

 

[Boatguy]

If peak loads are a problem, you can limit the charge rate on your MS (you didn't mention if you had 48a or 72a) to 30a and still probably get all the power transfer you need on most nights.