Future EV Charging and NEC

[WA_Sparky]

EV charging and NEC requirements.

A few years back I remember first learning about the level 3 DC fast chargers. Now im hearing more about companies trying to cut down on charging times, to do so, they are increasing voltage higher to allow for more KW charging (if they can solve heat dissipation issues). In this case specifically with Porsche's new Taycan it's designed to hit 800V. Usually when it comes to equipment I'm powering in a building I only have to worry about its first point of connection. Hypothetically if these chargers are pushed beyond 1000V, even though we may only provide 480V to the equipment; could this require us to follow the "Over 1000 Volts, Nominal" sections of the code?

 

[Jraef]

I don't see why it wouldn’t. That issue has come up in the solar PV world as well. The PV design engineers don't realize (or care) that the rules for the installation change at 1000V. In the early 2ks I was working for Siemens and was getting a lot of requests for us to come up with a 400-800A DC disconnect switch rated for 1kV DC. But when they found out what that was going to look like and cost, most of them changed their minds.

However, if the charging equipment has an internal transformer, and THEY provide the cords and connectors / plugs that THEY list for use at 1kV DC, then it is no longer an issue for the installing electrician. I think though that when the charger suppliers run into that issue, they may back off of the 1kV aspect. It's hard enough to find anything that is rated for 600VDC, let alone higher.

Side note; I just read an interesting article on the upcoming difficulties in providing rapid charging for rental units, especially in urban areas. It's a big enough issue that it could stall the drive toward electric vehicles. The author was a landlord who WANTED to put in EV charging capability in his units, but ran afoul of having too small of a service, and that upgrading the service would mean upgrading the entire electrical system in the 1940s era buildings. After reading this, I think the solution may be to allow/force utilities to have more than one service drop per address, so they can just get a NEW service drop for a garage or carport that serves ONLY the EV chargers.

 

[retirede]

I think 800V will be the maximum for the foreseeable future. The systems in the car have the same issues with KV-level insulation.

 

[petersonra]

I think there is a point where it becomes impractical to pump the power in any faster for consumer products like vehicles or battery storage systems for residences. With the present level of battery technology, we are probably pretty close to the limit of practicality.

There is also the problem of what the heck do you do when everyone plugs in their EV when they get home in the late afternoon and there is suddenly a 2X rise in demand for electricity at the same time the utility loses all the PV generation capacity?

 

[WA_Sparky]

I think there is a point where it becomes impractical to pump the power in any faster for consumer products like vehicles or battery storage systems for residences. With the present level of battery technology, we are probably pretty close to the limit of practicality.

There is also the problem of what the heck do you do when everyone plugs in their EV when they get home in the late afternoon and there is suddenly a 2X rise in demand for electricity at the same time the utility loses all the PV generation capacity?

As the EV vehicles make their way to more and more homes this could definitely impact the grid. My guess is sometime in the next 20 years there will be a push for new homes to have PV and battery banks to cover that potential dip in the grid. Government might even pay for some of it. I remember the utility did this a while back for the large populated city near me (Portland OR). They would pay for generator install for a large building if client agreed to allow them to have remote access to pump power back into the grid if they couldn't keep up with demand.

 

[wwhitney]

There is also the problem of what the heck do you do when everyone plugs in their EV when they get home in the late afternoon and there is suddenly a 2X rise in demand for electricity at the same time the utility loses all the PV generation capacity?

Well, since the free market is efficient at allocating resources as long as the market has the proper internal price signals, you offer one electricity rate for immediate use, and a lower electricity rate if you allow the utility to schedule your EV charging. That lets the utility smooth the demand.

Cheers, Wayne

 

[drcampbell]

... There is also the problem of what the heck do you do when everyone plugs in their EV when they get home in the late afternoon and there is suddenly a 2X rise in demand for electricity at the same time the utility loses all the PV generation capacity?

First thing we do is abandon old-school rigid thinking and "we've always done it that way". The 9-5 workday originated with sawtooth-roofed factories that relied on daylighting. Now that electric light has caught on, there's no compelling reason to retain the rigid 9-5 schedule.

After that, smart grids and smart consumers that optimally match demand with availability. You might plug it in when you get home, but if it needs only two hours to top it off, it might wait until 4:00 am to begin charging. One of the nice things about EV charging -- unlike, say, lighting & telecomm -- is that whenever there's a power deficit, it can be interrupted without anybody noticing.

If we do end up relying on solar, and abandoning the 9-5 workday slowly, we can install a lot more at-work chargers.

And we can do a lot of load shifting. If we get to the point that solar is so abundant that the smart grid needs to tell the solar inverters to drop off line because there isn't sufficient demand, we can shift the demand there. Make ice during the peak summer hours and cool buildings with chilled water. (some of this has already happened) In wintertime, heat up firebrick with on-peak energy and release it slowly, as needed. (this, too, already exists)

And none of this is going to happen instantaneously. Demand has grown incrementally in the past and will continue to do so in the future.

 

[electrofelon]

There is also the problem of what the heck do you do when everyone plugs in their EV when they get home in the late afternoon and there is suddenly a 2X rise in demand for electricity at the same time the utility loses all the PV generation capacity?

First, given the disclaimer that none of us are grid operators and probably none of us are really up on all the statistics.....But..... I have always heard that electricity consumption breaks down to about a third commercial, a third industrial, and a third residential. Doesn't lots of commercial and most industrial drop off in the early evening?

 

[James L]

First, given the disclaimer that none of us are grid operators and probably none of us are really up on all the statistics.....But..... I have always heard that electricity consumption breaks down to about a third commercial, a third industrial, and a third residential. Doesn't lots of commercial and most industrial drop off in the early evening?

Yes, because people leave work and go home

 

[drcampbell]

Yes, but if the incentives are sufficient, industrial users could change when they consume power.

Large wind tunnels (which probably account for 0.0000001% of the nation's energy consumption) almost always operate only at night to minimize demand charges.

 

[paulengr]

EV charging and NEC requirements.

A few years back I remember first learning about the level 3 DC fast chargers. Now im hearing more about companies trying to cut down on charging times, to do so, they are increasing voltage higher to allow for more KW charging (if they can solve heat dissipation issues). In this case specifically with Porsche's new Taycan it's designed to hit 800V. Usually when it comes to equipment I'm powering in a building I only have to worry about its first point of connection. Hypothetically if these chargers are pushed beyond 1000V, even though we may only provide 480V to the equipment; could this require us to follow the "Over 1000 Volts, Nominal" sections of the code?

Not necessarily. Spark plugs are around 20 kV.

Super-fast chargers will pretty much only be commercial. When you run a 3 phase DC rectifier what is the DC voltage? 145% of the AC nominal voltage. To go higher though we just add more diodes and capacitors in a ladder arrangement that multiplies the voltage up to whatever level we need at the output.

Voltage Multiplier - Multisim Live

Voltage Multiplier

www.multisim.com

 

[paulengr]

So as long as the high voltage is contained in the charger and cord NEC plays no role.

As to safety, consider that 4160 surface mining systems with a 25 A high resistance ground have 96 mA ground fault currents worst case which is high enough to cause pain but incapable of triggering fibrillation. BUT this is DC. Fibrillation is impossible.

But even better everything will be shielded either outright or with conductive rubber so even if you run a nail through it all you do is trigger the ground fault protection.

 

[hillbilly1]

As the EV vehicles make their way to more and more homes this could definitely impact the grid. My guess is sometime in the next 20 years there will be a push for new homes to have PV and battery banks to cover that potential dip in the grid. Government might even pay for some of it. I remember the utility did this a while back for the large populated city near me (Portland OR). They would pay for generator install for a large building if client agreed to allow them to have remote access to pump power back into the grid if they couldn't keep up with demand.

I worked on a distribution center many years ago that did that, they had two one meg generators that the poco could turn on and transfer at will. The issue that came up though, was every time they did that, the conveyers would have to restart, which usually took 15-20 minutes to reboot. They should have used co-generation parallel switches instead of standard transferswitchs.

 

[Seven-Delta-FortyOne]

BUT this is DC. Fibrillation is impossible.

DC can cause V Fib, just at higher current values than AC.

Along with A Fib and various other cardiac disrythmias.

 

[garbo]

I think there is a point where it becomes impractical to pump the power in any faster for consumer products like vehicles or battery storage systems for residences. With the present level of battery technology, we are probably pretty close to the limit of practicality.

There is also the problem of what the heck do you do when everyone plugs in their EV when they get home in the late afternoon and there is suddenly a 2X rise in demand for electricity at the same time the utility loses all the PV generation capacity?

Even better yet where is parts of NY & CA going to get power from in a few years when they outlaw all natural gas for new homes followed by maybe 10 years later they want all existing homes to get rid of all natural gas. So if you convert a home to electric heat, water heater& stove/ oven then add 2 EV cars that have to be charged at night when roof top solar provides no power. Might have to install 300;or 400 amp services to homes. Where I live people in town houses with no driveways or garages are almost always not able to install an EV charger. Have to love it when politicians make major changes that are not possible in the time frame they dream up.

 

[wwhitney]

Have to love it when politicians make major changes that are not possible in the time frame they dream up.

No one is proposing that in 2032 all CA residential houses are natural gas free and all vehicles are EVs. With proper planning there is time to gracefully decarbonize residential houses and transportation.

Cheers, Wayne

 

[ggunn]

...followed by maybe 10 years later they want all existing homes to get rid of all natural gas.

Do you have any evidence to support that there is any such plan? My home was built in the 1980's and it has no wiring in place to enable replacement of my gas stove and water heater with electric appliances; who would pay for that?

 

[Jraef]

There is a lot of misinformation out there in the alarmist media about this issue of "California banning natural gas appliances". There is NO STATE PLAN for this to change. The state has made a plan to ENCOURAGE changing to all electric, but making the Energy Code prefer heat pumps for heating / cooling (which are more efficient anyway) and forcing builders of NEW homes to make them "electric ready" even if they provide gas heating and water heating (which also requires being designed for solar PV and EV additions). Builders can still build new homes that have natural gas appliances, but5 must "make up for it" in other efficiency gains in the construction methods etc.

To date, 40 CITIES in California have made plans to phase out gas appliances as much as possible. The most aggressive of those is San Diego which will ban natural gas connections for NEW CONSTRUCTION starting in 2023, followed by a planned goal to CHANGE from gas to all electric in 45% of existing homes by 2030, with a GOAL of 90% conversion by 2035 (including 100% of MUNICIPAL buildings by that time). So from that I can deduce that they understand that there will always be exceptions, it's just a GOAL. But keep in mind that Sn Diego has a VERY mild climate and in general, people who use gas heating hardly ever need it. My sister lived there until this year and had gas heat, she paid about $120/year for gas. Her bigger energy use was electrical, because of the need for Air Conditioning a lot more often, so converting that to a heat pump when it wears out would be a no-brainer. That's what we are going to see happen. Most likely they will make it mandatory for A/C systems to become heat pumps, i.e. you will not be able to get a permit to replace an old A/C only unit. gas stoves are such a small amount of the gas use that I doubt anyone will pay much attention to that other than to offer financial incentives to change to electric heating, i.e. induction cooktops and convection ovens.

San Francisco is one of the other big cities that is banning gas appliance on NEW construction. But keep in mind there that "new construction" in SF is basically relegated to high density apartment structures where, because it is earthquake country, already makes gas appliances unpopular. So it's a "grand gesture" that looks good to the greenies, but in reality does not really represent a huge change. There are people who WANT to mandate retrofitting, but a study came up with a cost of up to $5.9 billion to do so. The most often discussed alternative plan is to force the change on sale of a property and/or to force it at a natural replacement cycle by not allowing replacement gas appliances to be sold or installed without a special permit. None of that is finalized though, because even that is forecasted to cost between $600 million and $2 billion stretched out across the next 28 years (the goal for SF is zero greenhouse gasses by 2050)..

The good part of all of this though; LOTS of work for the electrical trade...

 

[garbo]

No one is proposing that in 2032 all CA residential houses are natural gas free and all vehicles are EVs. With proper planning there is time to gracefully decarbonize residential houses and transportation.

Cheers, Wayne

Sure that I read about Ca allowing natural gas in all houses but not sure if it was the entire state. We all know that you can not believe everything that you read on the net. Did remember that after 10 or 15 years after the gas use stoppage in new homes CA & part of NY wants all homes to remove natural gas services to all homes.