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ccutrer
Active Member
Sorry, this is off topic, but you know what I see all the time? Using 8AWG NM (technically rated at 40A) to feed 50A stoves and hot tubs. My own hot tub is wired this way, and there's no way I could fix it without ripping up half my basement and probably disassembling my deck. Luckily I'm not worried cause I know my hot tub maxes out at 17A empirically. Anyhow, you can't stress enough that a Tesla will pull exactly 40A from a 14-50 (or whatever a wall connector is set for), and will do so for hours on end. You can't be undersizing these things and figure "meh, appliances never pull their nameplate rating anyway, it's fine."
ssq
Member
I asked the team@Chai about the gateway and they said its not going to work with my utility, yes its SDGE again - thats one more reason why they suck!Very cool product ... check out the video
Has anyone used this to monitor power usage?
Their app did not work either for me. I would have loved to use it, liked the energy signature concept - maybe @FlasherZ and @ccutrer can help us n00bs understand the merit of what these guys claim and whether its a genuinely good product.
FlatSix911
Porsche 918 Hybrid
ssq
Member
Yes, they claim on their website it works with most SoCal utilties => How can I create an account with my utility? | Chai Energy
For me the app was stuck on gathering data, this may take 24 hours for 5 days. Then I installed an update and it was stuck on the screen, this may take 72 hours for another 5 days before I uninstalled the App.
ccutrer
Active Member
Looks interesting. I have a TED Home Pro monitoring both overall usage, and several individual circuits. For a while it sent just the total usage to a website that claimed to be able to automatically figure out your appliances. It was hilarious to see it change its mind daily about what kind of appliances I had. This product looks to at least let you tag the appliances, but that's only accurate to a point. When I'm looking at my overall usage I've gotten pretty good at knowing what's on (hot tub is 4kW, dryer is 7kW, A/C is 3.5kW, furnace blower is 700W), but for smaller things there's just too much noise and base load to accurately identify out of the aggregate.
ccutrer
Active Member
K-MTG
Sunshade Captain of TMC
ccutrer
Active Member
More derailing: I love SolarEdge! I have an SE11400. Speaking of properly sized conductors, it's a beast to get 6AWG into their terminals, but the monitoring is awesome.Yes @K-MTG we have discussed this, thats the eventual product I am going to get. My Solaredge SE5000 doesn't show consumption data.
Sorry All, for derailing this threadbut so much good info being exhcanged!
ssq
Member
I checked with my electrician, he says he has put in #4 THHN between the main panel and Tesla HPWC. Is the "at 90°" n operating temperature rating qualifier?
ccutrer
Active Member
It's Celsius. I'm not a licensed electrician so @FlasherZ can probably correct me if I say anything wrong. But the temperature rating is for the insulation and assembly of the entire cable and conduit. NM cable is non-metallic and should not be in any conduit, so must always use the 60° column, regardless of other factors. The 90° column can be used if the type of wire (THHN is what we're discussing here), the conduit, how many other wires are in the "raceway" (I think it's called the fill factor, and is actually taken as a derating of the full ampacity), and the ratings on the terminals are all at 90°. So if he really put 4AWG THHN in appropriately sized conduit between the panel and wall connector, yes you can use the 90° column and get 95A (not 100A). Set your wall connector at 90A (I don't think it has a 95A setting). The 100A breaker is then okay, cause if the ampacity doesn't match a standard breaker size, you can go up one (probably subject to some caveat I'm not aware of). Or you could go down to a 90A to match the wall connector setting and not worry about it (but possibly not a cheap and easy to find breaker).
ssq
Member
Great information, thanks for clarifying. However he did not use metal conduit with the #4 THHN. The two THHN sets (one to the subpanel and other one to the HPWC) are laid out separated by approx 16" inside the drywall. I don't know about the temperature rating yet but I can easily find that out tomorrow by asking him or simply checking the wire labeling in the main panel where they terminate.
ccutrer
Active Member
THHN should be rated for 90°. The breaker likely is as well (most if not all breakers of that size are). The wall connector definitely is. I'm about 90% certain that THHN in direct insulation contact is not an approved assembly (is there insulation?). THHN just within drywall I'm pretty sure is not an approved assembly either, but less likely to immediately start insulation on fire when run at full amperage. As to derating the wire for this particular raceway - I have no idea what do, since it shouldn't be allowed. Probably just use the 60° column, which gets you back to 70A.
ssq
Member
No insulation or any sort of filling in the walls. I live in San Diego so I doubt any walls have insulation here except the attic.
This is the structure/layer I see => Stucco || black paper like lining(moisture blocker?) || Wooden framing|| Drywall.
So now I'm worried about the THHN passing though 2" drilled holes in the wooden framing. Lots of questions to ask the electrician tomorrow when he comes to collect the check.
CmdrThor
Active Member
Yea that doesn't sound like a legal installation. I would withhold payment until it is done correctly (and passed inspection). I used 3-3-3-5 copper SER to feed my subpanel from a 100A breaker on my main panel. My inspection will be early next week, hope I pass!
I hope yours passes but I just got installed 2/3 NM-B copper to a 100amp sub panel in the garage
That's still an illegal install.
First, the 90 degree column of #4 is only 95 amps. Even then, that wouldn't count because termination ratings at the breaker and HPWC terminals tend to be 75 degC, which means #4 is limited to 85A.
- Sections 625.40/625.41 state that vehicle charging loads are always to be considered continuous loads.
- Section 210.19(A)(1)(a) says that "Where a branch circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the minimum branch circuit conductor size shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load." An HPWC configured for an 80A continuous load, then, requires a conductor with an "allowable ampacity not less than" 100A.
- Allowable ampacity of conductors is defined in section 310.15. The 90 degC column of 310.15(B)(16) states that the ampacity of #4 copper conductors is 95 amps, and 75 degC is 85 amps.
- You cannot even use the 90 degree column because termination ratings on your breakers and the HPWC are 75 degC.
- As 95 and 85 amps are not "not less than" 100 amps, #4 would not be usable for this application.
- The 240.4 "next size up" rule, for breakers only, doesn't apply to conductors, so it cannot be used.
This is also an illegal install if that subpanel contains a 100A breaker for a wall connector configured to 80A. It is legal only if the wall connector is configured for the 72A charging setting on a 90A breaker. See the same section in the FAQ mentioned in the post directly above.
However, I will say that many inspectors will pass the configuration, and since the inspector's opinion is the only one that matters, good luck with it.
Most of the local inspectors I've talked to will red-tag #2 NM cable in an application requiring 100A.2/3 cable is rated to 95A when installed per art 334. Many electricians say "yeah, it's only going to be charging at 80A though!!!" and neglect to read one of the most basic articles of the Code (210) which says the conductor must be rated at not less than 125% of continuous loads. 80 * 125% = 100A. Conductors that are rated less than 100A don't qualify.
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