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Preparing for your Model S: Selecting outlet, Solar City, etc.
- Thread starter bonnie
- Start date
Installed my 6-50 plug on 8awg wire and 50 amp breaker in my garage yesterday. Circuit has been set up for years on an extra dryer which I don't need.
Well I noticed my kitchen oven light blinking and sure enough the dryer line and oven are on the SAME BREAKER not on same wire though.
I understand the breaker may trip if I bake and charge at same time. But its not a fire risk to my knowledge.
My box is full and would need a new sub panel to ad separate breakers.
I am wondering if the s will detect this and cancel charge or limit ampacity?
Any comments suggestions are welcome.
from my Samsung galaxy s3
Well I noticed my kitchen oven light blinking and sure enough the dryer line and oven are on the SAME BREAKER not on same wire though.
I understand the breaker may trip if I bake and charge at same time. But its not a fire risk to my knowledge.
My box is full and would need a new sub panel to ad separate breakers.
I am wondering if the s will detect this and cancel charge or limit ampacity?
Any comments suggestions are welcome.
from my Samsung galaxy s3
JackA
Member
I am not an electrician: however, I watched an electrician yesterday as he installed a 100 Amp circuit to our detached garage. I am not visualizing how your oven and new outlet are not "sharing" some wire. The breakers I saw being used yesterday only have one set of connection lugs so the wire from the load center breaker must be split at some point, one to the oven one branch to the new outlet. I was told by the electrician that the ratings are based on one hour continuous use that is why the expected load should be no more than 80% of the rated capacity. This is to reduce the heat build up in the wire and connectors according to him. A few hundred dollars spent with an electrician might be much less costly than a fire loss.
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I was warned that 8ga wire is not adequate for continuous 40amp draw and actually had my electrician change out to 6ga.
I see.. well I guess I better reconsider my setup. Thanks for the advice.
from my Samsung galaxy s3
8 AWG can be used when the proper wire is used, all components are rated at 75 deg C or 90 deg C (breaker, wires, conduit, etc.) and you don't have to de-rate (either due to high temp attic runs or packed conduits, etc.) There is no easy guide for this because the NEC deals with different wire types. For example, if you used type NM cable (typical all-in-one black-sheathed Romex multi-wire cable, like 8/2) it isn't good for 50A with #8, but separate wires in conduit or type MC cable is ok. You have to check your wire / cable's ratings and types.
EDIT: Oh yes, and the length of the circuit. #8 for anything longer than a short garage run should probably be avoided.
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A few things:
1. Since you added a new outlet, it must conform to code. An electric dryer and a range/oven may not share the same circuit.
2. When you say they're on the same breaker but not the same wire, and you installed this breaker, did you attach multiple wires to each screw terminal on the breaker, or are they pigtailed together inside the box? They must be the latter - even if it were legal to share the breaker, you cannot have two wires connected to a breaker screw, to be legal.
3. What breaker was formerly in the box? Wiring, receptacles / appliance nameplates, and OCP devices (breakers) must be matched. If your oven was a 30A oven on #10 wire it cannot be connected to a 50A breaker.
4. Given your location, I am assuming that your county / city subscribes to current code and requires inspections. Installing a new breaker and outlet will typically require a permit and inspection. If you didn't do this, selling your house later may create a problem -- in some jurisdictions, it can cause you to have to bring the ENTIRE HOUSE up to code at your expense before you may sell it. You should check with your city hall / county inspector.
What type of panel do you have? Some panel brands have compact breakers, 2 in one slot. You could combine 4 120V circuits into 2 slots to make room for a new double-pole breaker. Before you do this, you'll probably need to do a load calculation to make sure you're not going to oversubscribe your panel too much, since you're adding such a large load.
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I was looking for a good consumer-friendly table with some web searching. Didn't find one I really like, but this one was interesting...
American wire gauge - Wikipedia, the free encyclopedia
The "NEC copper wire ampacity..." column seems to line up with what you're saying.
Does this imply 1 gauge for wiring to the HPWC?
No. I don't have the HPWC final specs, but I'm assuming based on published information it requires a 100A circuit and wire for an 80A continuous load. Assuming 75 or 90 deg C ratings (and that you don't need de-rating), you're normally looking at #2 wire (115A/130A rating), although #3 would be good enough. It's much harder to find #3. Keep in mind this is for copper wire, usually THHN.
(#1 is hard to find too, you'd probably have to go up to 1/0 if you needed it.)
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That was my understanding as well.
What leads to that assumption, as opposed to the 60 deg C?
Thanks for the info.
Most wiring (especially current-generation individual conductors in conduit), breakers, conduit, and receptacles, etc., are now UL listed at 75 and 90 deg C. The only issue becomes if you have to de-rate because you have tight conduits, or hot attic runs, etc.
Got it. Thanks.
So here's an example:
Cerrowire 1,000 ft. 2-Gauge Stranded Aluminum USE Cable - Home Depot
2 gauge wire. When you click the Specification link under MORE INFO, it includes:
You have to be careful with the wire types. Type USE is underground service entrance wire. Article 338 of the NEC covers its uses. Because USE is intended for underground service entrance, it is not required to have flame-retardant covering/insulation, and as a result 338.12(B) states that type USE may not be used for interior wiring at all.
Typically, for ampacity that big on an internal use, you'll use type THHN in conduit, it's much easier to work with.
Edit: The wire you linked is also AL wire, not CU, so its ampacity is much less.
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I did not actually add an outlet- it was in my home when I bought it- I just converted the outlet from dryer plug to the nema 6-50 as a solar city electrician said my outlet could do- the 8 gauge wires are individual copper and the run is very short- maybe 8 feet.
I did not add a breaker I am using a 50 amp breaker that was already installed- I dont know if the lines are pigtailed or what so that I need to investigate yes. I also do not yet know the amps required of my oven. Perhaps 50 is too high for typical oven.... I will have another electrician take a look at this point. Thanks for the advice.
It depends upon your jurisdiction, but in most cases if you did anything other than replace a like-for-like receptacle (for example 10-30R with the same model) -- if you ran new wire, or changed breaker size, changed from NEMA 10 series to 6 or 14 series, or extended the circuit -- it's a permit-required change.
You mentioned a dryer outlet, those are usually 30A... what was the old receptacle? If it was a 30A outlet on the 50A breaker, that's dangerous. It's safer now, except for sharing the breaker with the range. If you converted from a NEMA 10 series to a NEMA 6 series, is your breaker in a sub-panel or the main service panel? If a sub-panel, you might need to move the wire from the neutral bus of the panel to the ground bus, as a NEMA 10 is a hot-hot-neutral and NEMA 6 is hot-hot-ground. In an older panel or a service panel, the two may be bonded so it won't make a difference. HOWEVER, sharing that oven then becomes problematic, as it may have need for 120V/240V, which would have return current flowing on the ground wire. That's why you need permits, this stuff gets complicated.
As for the oven, it really depends upon the nameplate -- whether it's a range, a single oven, a double oven, a combination microwave/oven, etc. The nameplate will tell you the minimum ampacity required and, if direct-wired, the maximum circuit size.
Finally, as to your question, no, the car will not sense and adjust based on other loads on the circuit -- your breaker will just trip if you run the oven and charge the car at the full 40A at the same time.
One final thing for you -- should you insist upon keeping the breaker-sharing arrangement (against code), please make sure you do not have a Federal-Pacific Stab-Lok panel (typically breakers are black numbers on an orange face on the end of the breaker) or a Zinsco panel. Those panels are notorious for failure to trip and will be a severe fire hazard on that circuit.
spatterso911
P100DL - Raven
I've got a quote from SC to do a short run (1 ft) of 100 A to HPWC and a long run (25 ft) to install a 14-50 (opposite side of a 2-car garage). $1650. Good deal??
dflye
S Sig Perf 414, VIN 814
We had two 14-50 plugs installed on opposite walls in our garage using conduit from an existing sub-panel in the garage, probably a bit over 50' of conduit involved, total cost was about half of what you were quoted. Not sure if the 100A HPWC run would increase the price that much, or if there are other challenges for your particular install.
The work we had done was through a company already on site doing a solar PV install, so not sure if we got a price break due to them already being on site for the larger project.
Depends on the work required. If you have breaker space, room in the panels' edge for the cut-outs, and are going with surface-mount boxes, conduit, and receptacles, it seems rather high. If you need some circuits moved to make room in the panel, or the electrician will be digging in walls, running things in the attic, cutting boxes in, etc., you might be approaching that figure.
spatterso911
P100DL - Raven
I have a full size Square D surface mount panel inside the garage (200 A) with only 2 breakers in it for my PV system. The run would be about a foot to a surface mount box to manage the HPWC, and about 25-35' run from the panel, up the wall, across the ceiling, across the garage (2-car), down the wall again to mid point for the 14-50 plug. All surface mount. No need to hide the conduit. I'm surprised by the price, but it appears SC is using a standard price regardless of the run. I have thought about hiring an electrician to do this instead of them and see what price I get. I don't really believe that this install should cost $1650.
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Given what you have described, including parts it should be considerably less than that, perhaps a 1/3 of that.
PS: If you're going below the panel with the HPWC, leave yourself some room if you need additional exit from the box in the future - if you can go 18 or even 24 inches you'll be thankful later.
I had a quote from a local company that I've used several times before, including a discount for me as an existing customer to $1800 to install a 14-50. (I don't think they had done one before.) When it was all said and done, the bill came in at $1300 since the whole thing went a lot faster than they had expected. Stand-up guys. PM me if you're in the Silicon Valley area and want a referral.
Now I just need a car to try it with...
Now I just need a car to try it with...
