Dedicated circuit - is it necessary?

I'm using a branch circuit- there's an outlet on my front porch. There can be other things on the circuit- as long as they're not big draws and not in use when the car is recharging. I have my charger start at 4:45AM to be done by 7:45 before anyone else uses anything else on that circuit.

 

Parking lot lights on same circuit. Voltage is at 104 volts (should be 120 volts) Check out my data logger charts at "Attention Kill A Watt Nerds" thread.

 

Every time you hear about people coiling extension cords into their cargo bay so that they can get electricity on exterior circuits at work...hotels...parking garages...etc?
They're not worried about "dedicated" circuits, are they?

In my never to be humbled opinion, you don't "need" a dedicated circuit....simply one that's capable of supplying about 12A for an extended period.
Example: Electrical outlet in your garage that's not also supplying a large air compressor, a refrigerator, or a string of exterior lights, or running a 12A Bissell vacuum cleaner, etc.
If you're familiar with the electrical wiring in your house, you should be able to tell whether or not the circuit (plug) that you're interested in using is capable of charging your PiP by determining what other loads you have plugged into the same circuit.
Chances are...if there's a 20A breaker protecting this plug and you're not also supplying a kitchen circuit...or running a washing machine...or other large appliance, then you'll be fine.

Basically?
You have a couple of options:
1. Plug. Charge a few times. Check for lifted ("blown") breakers.
If there are none?
You're probably going to be OK.
It's not that tough. You're just hanging a 12-A load on your electrical system for however many hours it takes to charge a PiP.
Try to determine what other lights and receptacles are being supplied by this circuit and try to avoid plugging a vacuum cleaner, or a leaf blower or air compressor or any other large item into the same circuit while the PiP is charging. If you lift a breaker? Don't dial 911! Just unplug whatever caused it to trip, reset the breaker, and go on with your life. That's what breakers are for. If it happens a lot? Like more than once a month? Pop a flare over your local, properly licensed electrician if you can’t figure out why and correct the problem.
The circuit breaker that supplies the electricity to whatever outlet that you're using has a number on it corresponding to the current that it's rated to allow to flow before it trips. Usually? It's 15-20A. (20 is typical, although 15A circuits are getting more common.)
That means about 12A for the PiP and around 8 amps for anything else on the same circuit.
An outside light?
You'll be OK.
TWO outside lights?
You’ll still be OK.
Consider CFL’s or LEDs if you’re that worried.
A refrigerator, space heater, and a leaf blower?
You'll probably get to find out which breaker is supplying the circuit when you reset it.
That's option #1.

Option #2. Worry like hell. Call a licensed electrician to inspect your home electrical system, and get his or her advice as to whether you "need" a dedicated XX-amp circuit (GFI, of course!) installed to charge your PiP. He or she "might" translate this as "Do I need to hire you to pull permits and perform three or four figures worth of work on my house?" and respond accordingly.
Times are tough.
Contractors are hungry. If the electrician tells you that you "need" a dedicated circuit....get a second and third opinion.
Your wiring might be substandard for running a 12A load for however many hours that it takes to charge a PiP.
If this is the case.....you may want to consider bringing ALL of your wiring up to code before you plug in a vacuum cleaner (mine is 14A) or a leaf blower. Granted....you're only using those two appliances for a brief amount of time...but hey? Why take chances?

Tip: (current value: <$0.02) If you have to have a dedicated circuit? Or...more precisely, if somebody manages to convince you that you need one? Consider getting a 220V outlet wired as well.
If you're a homeowner, and if you believe that the whole EV thing will work for you eventually you'll want one anyway, and it'll be cheaper to get two jobs done at once.

Me?
I'm not much of a worrier.
I'd go with option 1.

Good Luck

 

I charge on my normal garage circuit that also has a washer, lights,garage door opener, dryer etc. never care what's operating and have never had a problem. Charges in same amount of time with either the washer or (gas) dryer going (sometimes both) or neither. Seems to make no difference. If there was an overdraw the circuit breaker would open and that's never happened. Only thing I make sure is off is the air compressor.

 

If you really want to be safe and obey the National Electric Code, don't put more than 4 other amps on that 20A circuit while the PIP is charging. If the breaker is rated just 15A, don't put anything else significant on it while charging. (I don't consider a single CFL or LED bulb to be significant.)

In other words, de-rate the nominal breaker rating to just 80% of its label. That is why the PIP draws only 12A, not a full 15A that would allow faster recharge.

 

If you upgrade the plug to a 220/240, you definitely want it on it's own circuit.

I just redid my old 1950's circuits and grounded most of them. In the process, I had my electrician run a new circuit for the car which was originally a 120, later upgraded to a 240. I asked if I could have a 120/240 split on the plugs, he said he didn't want to give someone the option of plugging onto the circuit which would overload or possibly degrade the wiring.

 

I use the front porch outlet at the house I live in, and when someone in the house is using a blow dryer to dry their hair, that is when we have to reset the circuit- so, at least in this house, we have to make sure I am not charging the plug in prius at the same time when someone needs to dry their hair

 

I plug my L2 OpenEVSE into the same outlet the electric dryer is plugged into. It's a 40A circuit. Both the dryer can run and the car can charge at the same time. YMMV. BTW, it's a relatively new dryer so it likely isn't anywhere near 40A.

But overall, you just have to add up the different devices using the same circuit. You need to assume 12A for the PiP, and add in anything else. And, you should stay at 80% or below of the rated breaker value on the circuit for the sum total of all the current.

 

you can do what you want as long as there is not a bunch of stuff that is on but keep in mind that if charging at 120 volts, the car is going to be drawing very near the maximum constant draw amperage so just about anything else drawing on the circuit is going to trip the breaker.

if you plan to charge on 240 and dont want to put in another circuit, i would branch off your dryer or something. Just wire into the plug, run some conduit to a socket and just make sure you dont dry and charge at the same time which should not be too difficult since i am guessing most of your charging will be done while you are sleeping

 

I think the reason they recommend a dedicated circuit is because charging the EV is roughly a 1400 watt / 11.6 amp affair. Same for why they don't want you to use an extension chord.

Extension chords would be okay too if they were heavy duty and carry the load without feeling warm to the touch. I'm using a 20 amp breaker and nothing gets warm. If the breaker pops in the middle of the charge you won't get a full charge. If your house burns down you won't get a good night's sleep. But it isn't rocket science... You can figure out what else if any is running on the circuit when you are charging... you can see what breaker setup you have, etc.

 

DITTO. I just got my PIP last week so I've only charged it a few times but haven't had any problems. I haven't tried charging with the dryer or washer running though, and I don't plan to. I was going to have an electrician come out and upgrade our 1960's wiring. It is a total mess in the kitchen. Toaster and microwave would trip the fuse. But so far, it seems like it is unnecessary for the PIP in the garage.

 

The breaker should open in case of overload. But a career in electricity has made me unwilling to bet my life or house on it. Instead of waiting for circuit breakers to pop, I obey the electric code deratings.

 

What derating does the code allow for a 1400 watt / 11.6 amp load?

 

The derating means to not intentionally load the circuit breaker to more than 80% of its rated value. For a 20 amp breaker and circuit, don't run more than 16 amps of devices at once. For a 15 amp breaker, don't run more than 12 amps.

By itself, your PIP is good on either size breaker.

If a washer or gas dryer is on the same breaker, I won't take lack of nuisance trips as an indication of long term safety. Another poster has a 240V charger on the same 40 amp circuit as an electric dryer. Before doing that, I'd check the dryer's nameplate to make sure it pulls no more than 20 amps. (20 amps dryer + 12 amps PIP charger = 32 amps = 80% of 40 amp circuit breaker rating.)

 

If you have an older home you may need to consider a separate circuit. I've been charging my PiP at my current rental for 18 months and 2 years before that at another home. A couple months ago we started hearing buzzing in an outlet inside the house (same wall) . Called an electrician last week because we noticed the wall was warm. The breaker never tripped. He replaced the switch but it looked fine. He diagnosed the problem as the amps needed to charge the car after testing that outlet, and recommended a separate circuit. I had gotten lazy and left the cord plugged in all the time, I don't know if this caused the problem or not.

The house is 50 years old. The only other things on the wall are a bedroom lamp, extension cord to charge phones, etc., light with fan, and shredder. The outside outlet looks on the newer side but I don't know about the wiring inside the wall.

Will investigate the cost of a separate circuit after trying to charge the car again and confirming that is what's causing the buzzing and heat (nothing else was on at the time).

 

I'm a little concerned that a licensed electrician would hear the symptoms you described above, replace a wall switch and (MAYBE!) tighten the outlet connections on the other receptacles and then recommend a separate circuit for one 12a load.
The shredder is the only other thing plugged into the circuit you described but what other things do you plug into those outlets?
How far would the new exterior branch circuit run, and how much would it cost?
Is the bedroom on the south or west wall?
Is the house wired with 12-gauge wire? Is it copper?

Buzzing and heat behind a wall are alarming symptoms.
Make sure your rental insurance is sufficient and maybe get a second opinion before getting the new circuit.
You may be sweeping a fairly dangerous problem under the rug.

Good Luck!

 

Glad I don’t own rental property