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FAQ: Home Tesla charging infrastructure Q&A
- Thread starter FlasherZ
- Start date
The HPWC's circuitry will be very, very minimal - only the car's load would really register. I suppose I should ask what double means? In my case, I use about 350 kWh/month or so for the car (but my normal load is between 3500 and 6500 depending on season).
Interesting, here's some usage (vs 2012) / consumption:
June, 2013: 1677 kWh, 2012: 1128 kWh,
July, 2013: 1475 kWh, 2012: 1045 kWh
[this is TOTAL consumption, inclusive of everything running in the house]
Lifetime is 313Wh/mi
My car has 8000 miles, and I believe ~2500 kWh lifetime consumption
- I've charged about 3000 miles outside of my hometown [superchargers, charging at hotels, etc.]
- my ChargePoint stats indicate approximately 878 (kWh) consumed - approximately 2800 miles(?)
- So that's about ~2000 miles charged at home, which is approximately 626 kWh. At 16.6/kWh, that's about $103.
Although I highly doubt the HPWC is the culprit, it is highly suspicious that the bill went up shortly after installing it (no other major appliances were installed).
Is it possible that there's an electrical "leak" in the HPWC?
mknox
Well-Known Member
I have a dedicated meter on my NEMA 14-50 outlet and here are some stats for you (as recorded by my meter, not the car):
April: 644 kWh / 2,066 miles
May: 790 kWh / 2, 474 miles
June: 719 kWh / 2,048 miles
July: 469 kWh / 1,259 miles
August: 716 kWh / 1,997 miles
This does not include some "opportunity charging" that I may do away from home (but would be minimal). I don't have a HPWC, but the kWh would be the same if I did. I just takes me a bit longer with the UMC to put the same kWhs into the car.
Sweet thanks - sounds like something is terribly wrong - either with my HPWC, or somewhere else in the house. I'll have to check it out and figure out what the heck is going on.
mknox
Well-Known Member
I just noticed that you said the "bill" went up whereas your original post talked about double useage (not the same thing). Could it be that you're on a tiered rate, and the added EV charging load has pushed some or all of your consumption into a higher rate tier?
swaltner
Active Member
If you want to check the power draw of your HPWC one-time, buy a Digital Clamp Meter like Shop Amprobe Digital Clamp Meter at Lowes.com will let you read the power draw of a single circuit in your breaker panel. You will need to pull the cover panel off your breaker panel and clamp this around one of the wires coming off the breaker for your HPWC.
To monitor electricity used by your car on an on-going basis, something like TED 5000-G Home Electricity Monitor is a good solution. This is a similar device to above (measures the magnetic field around a wire to monitor current flow), but it gets permanently mounted inside your breaker panel and can monitor the power usage on an on-going basis.
I have a TED 5000 installed with three sensors (House Breaker Panel, Workshop Breaker Panel, ClipperCreek LCS-25). With that I can see the total power usage of the hose and workshop, as well as directly read how much electricity is used to recharge the EV. The LCS-25 draws between 2 and 3 watts when it isn't charging the car. I would expect the HPWC to be similar.
mknox
Well-Known Member
I also have a 3-MTU TED (Whole House, Water Heater, EV Circuit). FWIW, the UMC draws between 0 and 2 watts when disconnected from the car. Most of the time it's reading 0 but occasionally I see it at 2 watts.
What about installing two NEMA 14-50's on the same branch circuit? I want to put an outlet both inside my garage and outside so I can charge even when another car is parked inside. My cable run is long and I plan to use a GFCI breaker, so running a second circuit would be very expensive. However, NFPA-70:2011 section 210.23(C) appears to prohibit multiple outlets >40A for anything other than electric stoves, but it's rather confusingly worded, and 210.23(D) appears to say the opposite so long as I put in a 60A breaker/outlet instead of 50A.
I don't think there would be any issues with it working properly, since you would only be using one plug or the other, correct? Basically like a hardwired extension cord.
Attached or detached garage?
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You're right in that it would likely work properly and this would be a safe use of a single branch circuit (provided you never plugged two vehicles in at once at full load); that said, I think it might depend on your AHJ (Authority Having Jurisdiction, or AHJ). It does appear that certain interpretations of the code may preclude this, although I'm not sure how often that provision is exercised.
I've posted the question in a couple of forums that contain electricians and inspectors, and we'll see what they say. EDIT: To clarify, your best bet is to call your local city or county inspector and ask them if it would be acceptable.Extension cords are prohibited by code, too.
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mknox
Well-Known Member
Definitely not allowed in my jurisdiction under Section 86-300 and 86-306 of the Ontario Electrical Safety Code.
Do you happen to have a link to the code citations, Michael? Unfortunately, unlike the States where it's codified and required to be public domain, I can't seem to find the code online for the OESA. From the excerpts I've seen, 86-306 doesn't expressly prohibit it as 86-306(1)(b) excludes the "single receptacle" wording for the 125V provision found in 86-306(1)(a), although I suspect that's just a technicality. Just curious.
I wanted to have two 14-50s in my garage for ease of access on the same circuit and my electrician said that was against code. The outlets would not be used at the same time. I'm in Virginia. The rationale was that when I sell the house the new owner may not realize the limitation and try to use both outlets simultaneously. Similarly, wiring both outlets on separate circuits to my sub panel was against code because it exceeded the total amperage of the feed to the panel. I would have kept one of the breakers open. Same problem. I even looked into an A/B switch that would force only one outlet to be connected at a time but it was cost prohibitive.
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That's not really the reason, as I'm willing to bet the total amperage of your 15A outlets in the kitchen would also exceed your 20A small-appliance branch circuit's breaker size. You were also being fed some BS when you were told that you couldn't because the circuits would exceed the feeder capacity. This happens all the time - feeder to a subpanel that has circuit breakers totaling much more. My poolhouse feeder, for example, is 60A. Inside the poolhouse is a panel that serves a 30A circuit for a wall heater, 2 20A small appliance circuits in the bathroom, a lighting circuit, 2 20A circuits in the poolhouse counter area, and a 40A feeder to an outdoor panel that has a 20A pump circuit, 2 20A outdoor receptacle circuits for pool maintenance, a pool light circuit, and a booster pump circuit. Never, though, is it expected that the poolhouse would draw more than the 60A. Feeders are sized for the expected load, not the total possible load.
That said, it does appear that 210.23(C) would preclude it on a single circuit in a "dwelling unit" (an attached garage) but in a detached garage with its own service panel, it would be permitted by 210.23(C) under "other utilization equipment". That's why the wording is so odd. Seems like this is going to be one on which you'd have to consult your local inspector.
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One additional point to the poster: You are not required to have GFCI circuit breakers on these circuits. The UMC has ground-fault capabilities built in already, and you'll be paying a lot for the 50A GFCI breaker. Save $90 per circuit and use a regular 50A breaker.
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mknox
Well-Known Member
Ridiculous as it seems, they don't post publicly. The least expensive version (downloadable PDF) costs $190 from what I can tell on the linked page. As a utility, we are not bound by the OESC (there are other safety regs that cover us), but we have a copy in our library. Based on the copyright notice and license agreement we have, I hesitate to post myself.
Section 86-300 says that EV charging equipment must be supplied by a separate branch circuit that supplies no other loads.
I could technically read that plus 86-306(1)(b) to permit multiple 50A outlets on a single 50A branch circuit supplying no other loads than EV charging loads. If only one of 2 receptacles is being used at any given time, then no other loads are attached. And unlike 86-306(1)(a) which specifies a "single receptacle" for 125V/20A or less, 86-306(1)(b) has no "single receptacle" text. Without the specific text I can't see if there's any other gotchas, but hey...
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