I am installing a 225 A, 208V panel board that will feed 8-40A ev chargers in a condominium. The customer would like to install 4 Enel x and 4 Tesla gen3 chargers. They would also like to use load sharing in the future as more residents become interested. Can you install a Tesla and Enel x in the same panelboard and still load share?
EVSE Load Sharing
- Thread starter mjc1060
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Whats load share? Is that a 'automatic load management system' ? If so you need to dig into the manuals for them.
Whats the maximum EV charging load the NEC will allow for a 225A 208V panel without load management?
My guess is 220.40 says to use the branch circuit values you calculated according to 625.42
Code:
625.42 Rating. The equipment shall have sufficient rating to
supply the load served. Electric vehicle charging loads shall
be considered to be continuous loads for the purposes of this
article.each Tesla charger is 6656 VA
and each Enel x is 9600VA
You have 26624 VA of Tesla and 38400 VA of Enel X chargers
Total VA is 65024
Now add 25% for continuous load 16256 VA
I get 81280 VA
or about 226 Amps
Now if you look at
220.60 & 625.42 Rating (second part)
Code:
Where an automatic load management system is used,
the maximum equipment load on a service and feeder shall be
the maximum load permitted by the automatic load management
system.
rnatalie
Senior Member
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- Catawba, NC
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Usually, you pay. You typically get some amount of supercharger time thrown in with the purchase. A few installations subsidize the use of the charger so the customer doesn't end up paying.
Yes I meant to say automatic load sharing system. Thank You that was very helpful
Happened to see this posting on a search and I can add some clarity.
First, it may be helpful to get up to speed on how EV charging actually works. It's rather clever. Here's a very well presented video (27 min.) that will not bore.
The high points:
- the actual charger is in the car itself.
- the charger can dynamically adjust its current draw.
- An EVSE is not actually a charger: it's just a contactor/relay, GFCI and tone generator.
- The EVSE tells the EV's onboard charger how much current it may draw. Really. (video @ 5:59)
- This can be changed "on the fly" by changing the duty cycle of that tone. Really.
The EVSE in the video is labeled "240V/30A" - but now you know, that's a lie. It's there to simplify life for inspectors and electricians. The EVSE could be programmed via software to send a different duty cycle tone, telling the EV it can draw *any* current.
Traditionally if you want to power four EVSEs off 80A of capacity, you provision 20A to each EVSE (so 16A actual charge x the 125% derate), so a subpanel and 4 breakers.
However, if you think about the above features, there's a design opportunity here. What if only one car is charging? Why is it plodding along at 16A when 64A is available on the feeder? "Because of limitations of old tech" is the only reason. Well, EVSEs can talk to each other.
That's exactly what's happened with the Tesla Wall Connector 3.0 and several other models. You configure one of them as a "master" and say "you have 64A to share". The other 3 are configured as servants - in Tesla's case they handshake wirelessly with each other, but some have a wired connection. The various EVSE's communicate their loads: if one is charging with the full 64A and a second EV plugs in, the second charger says "Yo, got a customer" and the master tells the first EVSE "cut to 32A" and then on confirmation tells the new charger "you have 32A".
When a car finishes charging, normal protocol is to send a signal to the EVSE saying "I'm done with power, thanks, you can disconnect me". At that point that EVSE gives its current share back to the pool.
This is a huge boon to drivers, since very often, only one EVSE is charging at a time. Being able to get "full-boat" means a much faster recharge and a happier customer.
How do you wire these? You wire all the shared EVSE's on one branch circuit rated for the whole shebang, taking special care to set up the share feature correctly. This is an exception to the "Dedicated circuit for EVSEs" rule, and it's approved by UL and in the instructions.
Anyway, it's important to think about this setup *before* you install a bunch of small branch circuits per EVSE. Activating the sharing "later" would require a total rewire.
Obviously, if you insisted on wiring a separate branch circuit to each of the sharing EVSEs, you'd need to run the "full boat system capacity" e.g. 80A to each EVSE. Otherwise you will trip the breaker in the frequent case when only one EV is charging.
First, it may be helpful to get up to speed on how EV charging actually works. It's rather clever. Here's a very well presented video (27 min.) that will not bore.
The high points:
- the actual charger is in the car itself.
- the charger can dynamically adjust its current draw.
- An EVSE is not actually a charger: it's just a contactor/relay, GFCI and tone generator.
- The EVSE tells the EV's onboard charger how much current it may draw. Really. (video @ 5:59)
- This can be changed "on the fly" by changing the duty cycle of that tone. Really.
The EVSE in the video is labeled "240V/30A" - but now you know, that's a lie. It's there to simplify life for inspectors and electricians. The EVSE could be programmed via software to send a different duty cycle tone, telling the EV it can draw *any* current.
Traditionally if you want to power four EVSEs off 80A of capacity, you provision 20A to each EVSE (so 16A actual charge x the 125% derate), so a subpanel and 4 breakers.
However, if you think about the above features, there's a design opportunity here. What if only one car is charging? Why is it plodding along at 16A when 64A is available on the feeder? "Because of limitations of old tech" is the only reason. Well, EVSEs can talk to each other.
That's exactly what's happened with the Tesla Wall Connector 3.0 and several other models. You configure one of them as a "master" and say "you have 64A to share". The other 3 are configured as servants - in Tesla's case they handshake wirelessly with each other, but some have a wired connection. The various EVSE's communicate their loads: if one is charging with the full 64A and a second EV plugs in, the second charger says "Yo, got a customer" and the master tells the first EVSE "cut to 32A" and then on confirmation tells the new charger "you have 32A".
When a car finishes charging, normal protocol is to send a signal to the EVSE saying "I'm done with power, thanks, you can disconnect me". At that point that EVSE gives its current share back to the pool.
This is a huge boon to drivers, since very often, only one EVSE is charging at a time. Being able to get "full-boat" means a much faster recharge and a happier customer.
How do you wire these? You wire all the shared EVSE's on one branch circuit rated for the whole shebang, taking special care to set up the share feature correctly. This is an exception to the "Dedicated circuit for EVSEs" rule, and it's approved by UL and in the instructions.
Anyway, it's important to think about this setup *before* you install a bunch of small branch circuits per EVSE. Activating the sharing "later" would require a total rewire.
Obviously, if you insisted on wiring a separate branch circuit to each of the sharing EVSEs, you'd need to run the "full boat system capacity" e.g. 80A to each EVSE. Otherwise you will trip the breaker in the frequent case when only one EV is charging.
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