Preparing for your Model S: Selecting outlet, Solar City, etc.

[rcc]

I live in the SF Bay Area and like many folks here, put stuff in the garage and park outside. Solar City is recommending a 14-50 outlet in an outdoor receptacle which seems reasonable to me. RV's hook up outside and get rained on all the time.

[xhawk101]

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

[JackA]

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

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.

[efusco]

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

I was warned that 8ga wire is not adequate for continuous 40amp draw and actually had my electrician change out to 6ga.

[xhawk101]

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

[FlasherZ]

I was warned that 8ga wire is not adequate for continuous 40amp draw and actually had my electrician change out to 6ga.

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.

- - - Updated - - -

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.

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.

[brianman]

Correct. 8 AWG can be used on a 40A circuit, which is good for 32A continuous. 6 AWG should be used on a 50A circuit, which is good for 40A continuous.

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?

[FlasherZ]

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.)

[brianman]

I'm assuming based on published information it requires a 100A circuit and wire for an 80A continuous load

That was my understanding as well.

Assuming 75 or 90 deg C ratings (and that you don't need de-rating

What leads to that assumption, as opposed to the 60 deg C?

Thanks for the info.

[FlasherZ]

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.