A mix of options would be preferable IMO. L1 outlets in most places, and some 
L2 stations marked with signs saying 4 hour limits. A notification system that 
charging is done or that a space is available would be a nice enhancement.

One thing is I'm not convinced that providing L1 120v outlets is actually much 
less expensive than providing L2 240v outlets (note I said outlet here, not 
EVSE/station). Why? Because the wire and conduit will need to be sized 
according to the continuous current demand. This in turn means using at least 
10 or 12 gauge wire to keep voltage drop at 12 amps over some distances. Big 
parking areas could need even larger wire just to handle voltage drop. At 240v, 
voltage drop will have less of an effect (percentage wise) for the same 
distance. In short, 240v outlets like NEMA 6-20 allow for smaller wire or 
longer distances. 
The other aspect the number of outlets per circuit. 240v is commonly done as 1 
outlet per circuit wheres 120v often has several outlets per circuit. This 
works for 120v because most loads are intermittent high loads (microwave, 
vacuum) or low continuous (lights, TV). EVSE loads are generally high 
continous. L1 EVSEs usually limit themselves to 12 amps; in a parking lot, that 
would need one circuit per parking space assuming EVSEs all were active at once 
together. In short, 240v needs the same number of circuits. (One difference, 
though, is 240v will use 2x the electric panel circuit breaker slots.)

It is also possible to do this with power rationing. Several OpenEVSE based 
solutions have been developed to allow multiple vehicles to share a single 240v 
circuit. Tesla has also done this with their high power wall chargers that 
allows up to 4 be linked together.

My recommendation: run wire/conduit that allows for an easy conversion from 
120v to 240v circuits. If providing dedicated outlets, plan on 12 amps per 
actively used parking space. If using linked EVSEs then check the EVSE specs to 
see its sharing capabilities.

Last consideration: I am getting the impression that newer EV owners tend not 
to be as interested in pulling out an EVSE each day to connect their cars. 
Doing so is a hassle (esp rolling cord up afterwards) and it leaves their 
personal EVSE vulnerable to incidents.

On December 14, 2017 11:32:32 AM CST, Bill Dube via EV <ev@lists.evdl.org> 
>I tend to agree with Paul.
>The installation of 120vac outlets are a tiny fraction of the price of 
>the installation of L2 charging pedestals.
>If you spread them around over many parking places, (like they do in
>great white north for block heater outlets) there will be less 
>competition and contention over them.
>Keep in mind that a single 120vac 20 amp outlet can easily supply an EV
>with 50 or 60 or perhaps 70 miles of charge over a 8 hour workday. This
>covers 99% of commutes.
>Level 2 or 3 may be what is sexy and flashy, but Level 1 is probably 
>optimal for charging at work, given all the constraints. The ~$7k you 
>would spend on installation a Level 2 charger pedestal would easily pay
>for 20 Level 1 outlets spread over 20 parking places.
>Bill D.
>On 12/14/2017 6:13 AM, paul dove via EV wrote:
>> I say put 120v outlets in every spot and let people park where they
>> Sent from my iPhone
>>> On Dec 13, 2017, at 3:55 PM, Cor van de Water via EV
><ev@lists.evdl.org> wrote:
>>> Correct,
>>> Green means "available" so you would instinctively expect an empty
>>> at a green light.
>>> I would suggest a slight change to the meaning of the colors:
>>> Red = charging (no matter how fast/slow)
>>> Yellow = charging ended, spot should be vacated as soon as possible
>>> (grace timer)
>>> Green = charging and grace timer ended, spot is available (even if
>>> EV still plugged in).
>>> Anybody parked in a "green light" spot is suceptible to ticketing
>>> towing.
>>> Grace time can be tuned to match need/demand, with appropriate
>>> When a "yellow" charging space is vacated, an EV can immediately
>plug in
>>> and turn the
>>> spot to "Red" again.
>>> If a spot next to the EV charging spot is available and an EV
>>> that urgently needs a charge,
>>> it should be perfectly fine to unplug a "Yellow" or "Green" charger.
>>> Preferably he leaves a note at the car, how to contact him and how
>>> he needs to charge
>>> before it is OK to unplug when the official EV charging spot is in
>>> again.
>>> Note that it is possible to implement a max charging time with this
>>> well:
>>> Towards the end of the max charge time the light turns yellow and
>>> the charge time
>>> has expired, it stops charging but may allow an additional grace
>>> before the light
>>> turns green again and you should be on your way (or moved out of the
>>> spot at least).
>>> At companies with high contention for too few spaces, it makes sense
>>> force everyone
>>> to switch during lunch time (for example max 4 hours charging).
>>> Many EVs already announce how long charging is going to take, so it
>>> should be
>>> no surprise how long one can leave the car before it needs to be
>>> Obviously it is user friendly if the charging station sends you a
>>> when charging ends
>>> and the grace time starts.
>>> -----Original Message-----
>>> From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of EVDL
>>> Administrator via EV
>>> Sent: Wednesday, December 13, 2017 1:40 PM
>>> To: Electric Vehicle Discussion List
>>> Cc: EVDL Administrator
>>> Subject: Re: [EVDL] Combating ICED EV parking spaces
>>>> On 13 Dec 2017 at 13:08, Lawrence Harris via EV wrote:
>>>> I would love to see a big light on the top of the charge head that
>>>> goes green while charging, amber when the charger ramps down to the
>>>> end of charge and red when done.
>>> Outstanding idea, but I'd recomment the exact opposite of the colors
>>> red for bulk charging, amber for absorption (last 20%), and green
>>> charged.
>>> That's  because almost every other charger used on personal gadgets
>>> (phones, cordless drills, and so on) uses those colors or something
>>> similar. It's read for charging, green for done, and sometimes you
>>> yellow or flashing green during the absorption phase.  I don't think
>>> I've ever seen any other charger that was lit up red when it was
>>> finished, except for a couple that never changed color.
>>> David Roden - Akron, Ohio, USA
>>> EVDL Administrator
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