Charging Question at 120v

I think two outlets is probably right as there is not a 120V 30 amp outlet in the configuration you need (straight blade - see attached).

 

the only negative i see to option one is if the breaker tripped, both cars would stop charging. but that is very unlikely. i would go with the one circuit. consider upgrading the wire size, so you can go L2 later. without much work, if you desire.

 

Option 1 will not be advised
If you have one charging already and another just about to plug in you will create voltage drop and car that was already charging will ramp down current
It is possible just not worth
Option 2 will be much better
I have two Prime and one is charged by 120v and another on 240 v
Temporary way you could use drayer outlet with extension cord to have 240v in garage
It is not cheap...but much less than hiring Electrician

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I am not an electrician. More specifically I am not an electrician in California or the city you live in.

Option 1 would work fine if nothing ever went wrong. If you have electrical issues, however, twice the power that the EVSE is designed for could flow through it without blowing a breaker. You want that breaker to blow just as soon as things go wrong, not allowing twice the power to flow to somewhere as if all was fine.

Options 2 prevents this by having two, smaller power, breakers. It is likely to be slightly more expensive, but much cheaper than the deductible on a new house.

 

Option #1 won't pass muster for reasons shown in koryliss's socket illustration.

That leads to a potential third option, if electrical codes and local authorities approve:

* Option 3: Put in a single 240V, 20 Amp circuit, with full size Neutral wire. I.e. split phase. Wire the two 120V sockets (in a single junction box) on opposite sides of that Neutral. This approach allows for the two 120V outlets to eventually be replaced by a single 240V outlet for L2 charging.

If using this approach, I'd use heavier wiring appropriate for a 30 Amp circuit for a future higher capacity conversion to 240V 30A. But it would still require 20 Amp breakers now (not 30 Amp) for those initial 120V sockets. And to avoid tripping both cars at once, consider using a non-ganged 20 Amp breaker.

 

Wow! Two Primes at once. That's jumping in with both feet. Well done! I am jealous, but in a friendly sort of way.

I am an industrial electrician (or was till I changed careers). @koryliss is right. You'd need some sort of adapter to connect the EVSEs into anything bigger than a 20A receptacle. And then you'd have the possibility of a breaker stopping the charge on both cars rather than just one. Separate outlets and breakers is easier and more reliable. It's tempting to factor in cost, but don't let it get in the way of safety and code conformity.

 

With room for one 40 amp circuit your answer is simple, but expensive. Google the clippercreek share2. Although best described on their web site, the share2 can support full 16 amp charging for 2 cars simultaneously. Moreover, it supports 1 car at 32 amps if the other evse isn't charging. (But our Primes can only take 16 amps). Fantastic product, and somewhat future-proof. I have one. Let us know what you think.

 

i think some electricians are more interested in making money than doing the right thing. no offense to my but @jerrymildred who i know wouldn't sink to that level. take his advice, and hire the electrician who agrees with him.

 

With that many tandem breakers already in place, I would also be prepared for the possibility that the existing service (apparently 100 Amps) might warrant an upgrade (to 200 Amps).

 

I think I counted 260 amps of breakers in a 100 amp service.

40 more amps of hours long full load may be unwise.

I could not see a brand name, is it a Square D service?

amazon.com/Square-Schneider-Electric-HOM4080M200PCVP-80-Circuit/dp/B00NO2533U

Getting the same brand and series service would allow you to reuse your existing breakers.

 

What about installing nothing and reducing charge to 8 amps on both Primes?
220V Prius Prime Charging Cable | Page 2 | PriusChat

 

That looks like a pretty old system. You might give serious thought to replacing the panel as @fuzzy1 and @JimboPalmer mentioned.

I think electrician one is being careful because he doesn't know what your actual load is. So is Number two. Three and four are a little braver, just looking at the space available. There should be a label that tells you how many breakers (single or double) the panel is made for.

Short of a new service entrance, and not knowing what the label says, you do have room for more 120V breakers. Looks like you could physically fit in one 220V (which wouldn't meet your needs) or two single or two double 120V breakers. But that might overload the incoming wires and/or the backplane since you're potentially adding as much as 27 amps or more with two chargers. (My PiP draws a little over 13 amps.) You only have one 100A breaker, so you're probably safe fully populating it, but with all those doubles, I'd be careful.

I would recommend checking how many amps you're drawing now while the lights are all on and the refrigerator and other appliances are on, especially whatever's on that 100A 2-pole breaker. Turn on everything you can from TV to toaster. If you have a clamp on amp meter, take the cover off the panel, turn stuff on, and put the meter around the incoming wires one at a time to see what you have. Keep in mind that there is the possibility of drawing more current that what you read, so I'd leave a good 30% for head room. Others may have a different fudge factor. And all of this is assuming the panel is made to accept more breakers.

I can't figure out the brand either. Doesn't look like Square D. Square D is what I prefer. If you can swing it, the QO series is nicer than the HOM, but both are good.

 

Keep the extension cord short and heavy and it'll be fine. Check it to make sure it and the EVSE don't get warm, just to be safe.

 

You can install 15 or 20 amp outlets to a 30a breaker. If you look around your house you most likely have 15a outlets tied to a line with. 20a breaker.

So both ways would work. But I'd opt for #2 myself

 

I'm seeing several suggestions that this is a code violation.

 

I haven't taken the time to look it up, but I would think it would be. You could melt down the outlet without tripping the breaker. Outlet and wires need to be able to handle at least enough current to trip the breaker without damage.