feeder taps exploit for ev charging?

E

eliprotiva

Member
Location
Missouri USA
Occupation
EV inovation
hi, im working on democrotizing ev charging, idea is anyone can plug in an evse to charge an ev by default. I want to use the tesla J3400 socket rated for 300 amps air cooled. I want the full 200 amps avalible if user buys such evse or small and cheap 32 amps evse. Plan is to feed total transformer load through signal pins using a ct and basically change ct ratio for transformer kva to keep a standard output for 100% load. I designed a phyical lock that enforces make and break at zero current and touch safe. My question is about NEC code and equipment grounding conductor (EGC). An evse enforces a 20ma max current on PE pin, given i dont have gfci that would mean i have to carry load fault current on PE contact thats rated for 80 amps contentious.
My question is can i use "outside feeder tap" rule (NEC 240.21(B)(5)) to get 200 amps?
https://imgur.com/bmGdnSA
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https://imgur.com/a/nacs
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https://imgur.com/undefined
 
retirede said:
Why do you need 200A capability? The maximum AC charge rate per J1772 (and NACS) is 80A.
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I want to allow many evse to be able to use 1 port. 32 amps is a common rate so thats only 6 vehicles charging. Think state parks, churches etc, we are at 1 ev per 1000 in rural Missouri. The second we get a cheap ev and lots of charging the numbers will go up. Also this plug will be used for the next 50 years and energy is trending towards free so we should expect more consumption. Transforms are already getting bigger
 
As to your question, The outside tap rule would not qualify, at least as drawn on your illustration. Note the conductors must terminate on an OCPD. Why not just put a small panelboard adjacent, with or without a tap rule, and then you could have branch breakers for each outlet?
 
eliprotiva said:
and energy is trending towards free
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The cost are continuing to go up as there is not enough supply to support the load....the being driven by the switch to more equipment being powered by electricity, and even more by the number of data centers being built. It will be decades before we can increase the capacity to match the growing loads.
Sure we can add wind and solar, but without extensive storage that actually acts to drive the costs up. not down.
 
don_resqcapt19 said:
The cost are continuing to go up as there is not enough supply to support the load....the being driven by the switch to more equipment being powered by electricity, and even more by the number of data centers being built. It will be decades before we can increase the capacity to match the growing loads.
Sure we can add wind and solar, but without extensive storage that actually acts to drive the costs up. not down.
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Also i think its not just a supply issue, but the grid infrastructure needs significant upgrading.
 
brycenesbitt said:
It's a time of day problem, not a grid capacity problem. Even the AI data centers peak and change depending on time of day.
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It is a grid capacity issue in many areas, and the lack of grid capacity is limiting the connection of solar in the PJM interconnect.
Also look at the spot prices when there is a lot of solar and wind available ...they drop to almost zero and that is a grid capacity issue. Right now, there are areas in California where the spot price is -$15.00 per mHW. There is no capacity to get the power to other parts of CA where the spot price is $35.00 per mHW.
Texas has spot prices ranging from -$30 to $35 per mHW right now.
 
don_resqcapt19 said:
It is a grid capacity issue in many areas, and the lack of grid capacity is limiting the connection of solar in the PJM interconnect.
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Yes! On the generation side.

The batteries are doing what they can. Note on the graph above the dark blue is all battery based time shift.
They soak up all that negative price electricity during the day, and sell it back just outside solar hours.

That said as far as I can tell, the OP posted about an odd feeder tap issue not the Duck Curve.
 
brycenesbitt said:
Yes! On the generation side.
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Not on the generation side...it is the capacity of the transmission and distribution systems.

Right now, in my small town, they are having to build about 4 miles of distribution line to have the capacity to connect a small solar farm. They have stopped work on the solar farm waiting for the utility to build the new lines. The building of such new lines in a very low priority for most utilities as the cost recovery is difficult.
 
electrofelon said:
As to your question, The outside tap rule would not qualify, at least as drawn on your illustration. Note the conductors must terminate on an OCPD. Why not just put a small panelboard adjacent, with or without a tap rule, and then you could have branch breakers for each outlet?
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goal is to have this in all meter bases in usa ready to plug in an evse. some people hate the look of utilty boxes, Also cost per address. also we need the evse to set the breaker size so a cheap small or large can be plugged in. goal is no electricains needed for evse swapping. Nema 14-50 has failed us for ev use.
 
eliprotiva said:
goal is to have this in all meter bases in usa ready to plug in an evse.
Click to expand...

Keep in mind it is usually problematic to tap in a meter base. Generally, it would have to be a "meter/main" type to even consider such a thing. Sime meter mains have breaker spaces, so that would be easy. If you have to tap a feeder, you are going to need some sort of box with overcurrent protection in it.
 
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