Thanks everyone, I learned a few new things from this thread! First, it is not uncommon for densely packed residential units (like my townhouse) to each receive two out of three connections to a 3-phase power. In fact, in my learnings elsewhere on the internet, most of NYC’s residential units are powered this way. Apparently my neighborhood in Santa Clara, too. Second,
@nwdiver points out that it is easier (cheaper?) this way for the electric company when installing transformers in a neighborhood with attached units.
I guess now I’m feeling a bit shortchanged, knowing that my oven could be heating faster and car charging 15% faster had I been on a 240v system. Ignorance was bliss.
Not just NYC. Everywhere in US multi-residence power systems tend to be three phase, supporting electrical systems serving multiple units, townhomes, condominiums, and many data centers also. So 208v is a common US norm.
Further since we all know that BEV charging is a continuous load:
"First is the definition of
ampacityfound in Article 100. Ampacity is “The current in amperes that a conductor can carry continuously under the conditions of use without exceeding its temperature ratings.”
Next is the 125% requirement in 210.19(A)(1) and 215.2(A)(1): “The minimum feeder circuit conductor size,
before the application of any adjustment or correction factor,shall have an allowable ampacity not less than the noncontinuous loads plus 125 percent of the continuous loads” (emphasis added). This requirement ensures that conductors and overcurrent devices are not operated continuously at over 80% of rating." source: IAEI
For that reason the maximum draw for a 208/30 outlet, the typical multi-unit-building average outlet, will be 22 amps. In common use typical actual draw is more likely to be about 200/21 or so.
BEV drivers tend to be upset about that. However, having had all my three Tesla's living happily with 208/30 rated, actual draw usually 200/21 or a little less, I have never had a problem. Why?
Simple, even when I drive >200 miles round trip, my cars always arrive with >20% SOC, and charge overnight easily to ~90% which I rarely exceed, or even 100% which I do when setting off on a very long trip. Faster charging really is not necessary for me.
Back in 2014 when I was taking delivery fo my new Model S P85D I was obsessed to find a way to get 240/60 at a minimum. Honestly, useless, because 208/30 nominal is always good enough and also generates less waste heat than would higher amperage, so is really more efficient. Of course were voltage to be higher, that would improve efficiency, but amperage not at all. For anybody who resides in any 208/30 normal outlet, using that without change saves money and simplifies the installation.
If you really want more amperage and
if your breakers are factory made as parallel and ONLY if actually built as a pair then you can get 208/60. Your panel does have dualed breakers but the panel seems full so unless you are changing the panel anyway this would be an expensive option.