SSonnentag
埃隆•馬斯克
I guess that would depend on your installation layout. In my case, I would not want multiple 75-foot conduit runs. In a garage with a nearby panel it wouldn't be an issue.
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60A Breaker -> 4 gage or 6 gage wire?
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I guess that would depend on your installation layout. In my case, I would not want multiple 75-foot conduit runs. In a garage with a nearby panel it wouldn't be an issue.
Yeah, multiple 75 foot runs would be a waste. In that case, I'd run a fat feed (Al or Cu) to a garage sub-panel, then individual branch circuits to the EVSE. Allows for other circuits too.
eprosenx
Active Member
I think what size charging ability you deploy all comes down to each individuals situation and goals. I would say there is no right or wrong solution here.
I will call out a couple data points:
I will call out a couple data points:
- After only owning a Model 3 for a few weeks I have had a couple of occasions where I came home after work and wanted to top off before going on a long trip. So I was glad to have the full 48a charge capability (I still did not get it as full as I would have liked - charged to 90% the night before, then got home after commute at 80% and wanted to take it to 100%, but only got it back to 90%)
- My commute is very reasonable (about 30 miles round trip) and I have been able to bring myself back up to an 80% state of charge (which I charge to every night) with an hour or a little more of charging each evening. This is clearly overkill, but it is nice to know I am back to 80% quickly in case I need to make an unexpected trip somewhere, the power goes out, or we have a natural disaster.
As a CAD designer that specifies this sort of equipment daily I will give my $0.02
Any load which is on 5 or more hours per day is considered continuous and must be multiplied by 1.25.
Need 48A x 1.25 = 60A required
Options:
Romex: #4 Cu Romex, or #2 AL Romex ( #3 technically works but isn't readily available) Needs to be through structure.
THWN/THHN in Conduit : #6 Cu or #4 AL. Ground required is #10 for Copper and #8 for Aluminum. Needs to be protected inside EMT or other raceway depending on environment.
As to the question about the HPWC wire sizing the answer is that a listed assembly needs to be tested by UL, and therefore can use any wire size allowed by the listing.
I believe but am not sure, that there is circuitry in the on board car charger that detects a thermal runaway condition (increasing resistance with heat), and automatically responds by drawing less power.
Any load which is on 5 or more hours per day is considered continuous and must be multiplied by 1.25.
Need 48A x 1.25 = 60A required
Options:
Romex: #4 Cu Romex, or #2 AL Romex ( #3 technically works but isn't readily available) Needs to be through structure.
THWN/THHN in Conduit : #6 Cu or #4 AL. Ground required is #10 for Copper and #8 for Aluminum. Needs to be protected inside EMT or other raceway depending on environment.
As to the question about the HPWC wire sizing the answer is that a listed assembly needs to be tested by UL, and therefore can use any wire size allowed by the listing.
I believe but am not sure, that there is circuitry in the on board car charger that detects a thermal runaway condition (increasing resistance with heat), and automatically responds by drawing less power.
You base your conclusion on this premise statement. Let's see if it's even true or not.
The original Model S came out with maximum charging capability of 80A.
Then they lowered it to 72A.
Then they lowered it even further to 48A.
The trend looks downward, not upward, so your premise isn't even right. As more and more fast DC charging infrastructure is getting built, the need for very high onboard chargers in every single car is getting less.
SSonnentag
埃隆•馬斯克
But you're only looking from the perspective of a single manufacturer.
I have gone from a Chevy Volt (3.3 kW)
to a newer Chevy Volt (3.6 kW)
to a Nissan Leaf (6.6 kW)
to a Tesla S100D (17.2 kW)
to adding a Tesla X100D (combined with S 19.2 kW, or 35.4 kW if on separate 72A circuits)
All Tesla 100 pack vehicles have 72A onboard chargers, not 48A.
YMMV
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Agreed. Bottom line is this. Buy/install what you're comfortable putting into your own place. Or what your home's infrastructure will allow. But as far as I'm concerned I am buying a $64,000 car. I'm not going to get too hung up on the relatively very inexpensive costs (for me) of an HPWC:
Charger: $537 with tax
60 amp breaker: $10
8'-4 awg wire: $45
Wall anchors: $8
Total cost: $600. Less than 1% of the price of my car. Benefit: I know I will get the fastest home charging possible for my Model 3.
Because (a) you shouldn't care if it takes 1, 6, or 12 hours to recharge as long as you have enough range for the day's driving in the morning (the only exception is if you are on a TOU rate with a narrow cheap window), (b) it's more efficient (less heating) and (c) it's much better for the grid and the environment to charge at a lower rate for longer periods.
EDIT: and (d) indirectly, it helps hold down your, and everyone else's, electric bill to charge at lower rates because it helps defray distribution and transmission upgrades, which are the major cost in getting power to your home. Depending on how transmission costs are apportioned in your region, it may actually reduce transmission charges (not just hold them constant).
Irrelevant. All that matters is number of EV miles driven per day and how long it takes to replace them. Consider the absurd case - Tesla releases a P1000D with 3,000 mi range. I drive home from FL non stop (Woo-hoo! Spring break! Party!) and plug into my 17mph, 24A dryer outlet. It takes ~100hrs to recharge. So what? I'm not driving to/from FL every day. As long as I can replace my daily miles and them some overnight, I'll eventually fill up.
Plus, EV's are getting more efficient, so kWh/trip goes down, shortening charge times with the same charging infrastructure (250Wh/mi on the 3 vs 333Wh/mi on the S)
Meh. IMHO, 400A is silly, unless the load calcs say it's necessary (and even then, it's still silly). Put in a TED/Sense/etc and let me know when you pull more then 200A. And if you do, don't be surprised if you smoke your pole transformer.So our planning ahead when we built our house and had solar installed was a good thing? 400A service was only $1100 more than 200A.
PS Multiple Tesla chargers can share a single power feed.
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It's 3 hours, not 5. And they have to be, well, continuous (on for 2, off for 1, on for 2, off for 1, on for 2 doesn't meet the definition).
Few, if any, home loads (other than EV charging) are really continuous. For example, heating appliances typically cycle on and off via a thermostat, even if they are turned on for hours. Roasting a Thanksgiving turkey for 4-5 hours in an electric oven isn't a continuous load. Unless you use the self-cleaning cycle, then maybe. But you won't have much left for Thanksgiving dinner.
NEC 100.1, Definitions - "Continuous Load. A load where the maximum current is expected to continue for 3 hours or more."
Also, 625.21 specifies that EV charging is always considered a continuous load, regardless of duration.
Careful here, you absolutely, positively, cannot wire AL directly to the HPWC. The terminals are Cu only. You can run Al to an Al-rated subpanel, disconnect, or spice (like a Polaris-style connector), then Cu to the HPWC.
Glamisduner
Active Member
Also consider that slower charging is easier on the battery.
It's not just the wire gauge that matters. You also have to consider the operating temperate and wire type. For example if you used 6/3 Romex NM-B from home depot that would not work for your 48A (80%) power draw on a 60A circuit, but you could use 6/3 copper THHN (75A circuit or 60A at 80%) or THWN (65A circuit or 52 at 80%) and still be under your power requirement. This is easier than running 4 AWG wire. The electrician is not just charging for the cost of the wire. It is also harder to run. See referenced chart. Ampacity Charts
Selecting the right type to get the gauge lower saves half the cost. Ask your electrician #2 to price it with 6/3 THHN or THWN, or price it yourself. Wire & Cable Your Way | Electrical Wire By the Foot
My older MS 60 can only charge at 40A, so I installed a 50A breaker and used 6/2 NM-B for a 40A power rating at 80%. You are correct you need 6/3 if you want a NEMA 15-40 receptacle, which is another reason I installed a charger not a plug (plus safety and looks). When I sell the house I will just cap the wires and put a plate over the box. What are the odds the next person needs a 14-50 receptacle in that exact location unless that have a Tesla and then you could just sell them the charger. Save the $ and run 6/2 THHN or THWN.
P.S. I didn't use ferrels, but I would have if I could have got then in time. It is much cleaner and they make better contact, but it isn't critical.
Selecting the right type to get the gauge lower saves half the cost. Ask your electrician #2 to price it with 6/3 THHN or THWN, or price it yourself. Wire & Cable Your Way | Electrical Wire By the Foot
My older MS 60 can only charge at 40A, so I installed a 50A breaker and used 6/2 NM-B for a 40A power rating at 80%. You are correct you need 6/3 if you want a NEMA 15-40 receptacle, which is another reason I installed a charger not a plug (plus safety and looks). When I sell the house I will just cap the wires and put a plate over the box. What are the odds the next person needs a 14-50 receptacle in that exact location unless that have a Tesla and then you could just sell them the charger. Save the $ and run 6/2 THHN or THWN.
P.S. I didn't use ferrels, but I would have if I could have got then in time. It is much cleaner and they make better contact, but it isn't critical.
FYI, ferrels are what the installation guide recommends. I skipped them since I couldn't get them right away, but they make the installation much nicer if you can get them.
Page 19
"3. Strip the service wires going to the terminal block on the top entry bracket 3/4" (18 mm). Ferrules are recommended."
Installation Manuals - Wall Connector
That is out of context and has no relevance to charging at home. ALL AC charging through the onboard charger in the car is extremely slow from the battery's perspective. You're talking about the difference between 7 or 11 kW for a battery that handles 120kW.
That chart is slightly misleading - most THHN you find is dual rated THHN (dry)/THWN (wet) with 90 degree C insulation, so you could use the 90 deg C column for a 75A circuit.
BUT - you need to look at the temperature rating of the wire AND the terminals it is attached to. I'm pretty sure the HPWC uses 75 degree terminals, and most (if not all) residential breakers have 75 degree rated terminals (I've never heard of a residential breaker that uses 90 deg C terminals). So you're limited to the 75 deg C column, for 48A charging max on 6 Ga THHN.
eprosenx
Active Member
Hope you meant "hot and hot". ;-) The HPWC does not use the Neutral.
Glad you got it worked out! I did 6 AWG and that was difficult enough.
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