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by bhhaskin 1347 days ago
That's not necessarily true. It sounds like most of the upgrades are about convenience to the power company. Not anything safety related, which is why older properties are exempt.

You also have to remember that it takes a lot of power to be able to change an EV in timely manner. It is easily the number one consumer of energy. Older neighborhoods utilities where never designed to do that.

5 comments

> It sounds like most of the upgrades are about convenience to the power company. Not anything safety related, which is why older properties are exempt.

That is definitely not true. An 80 year old house might not even have grounded outlets, let alone GFCI or AFCI protected outlets.

> You also have to remember that it takes a lot of power to be able to change an EV in timely manner

Nobody worries about how many electric ovens, clothes dryers, or air conditioners are in an older neighborhood. 240V at 30A is a trivial load addition, and even if it were to become a concern, there are existing mechanisms to shed load during peak usage. Even a crude cut-off switch, like many air conditioners have, would be sufficient.

GFCI and AFCI are great! But a home isn't going to burst into flames or explode without them. Which is why there are exemptions.

240v at 30A is most definitely not a trivial load. Most homes have 100 amp service. That would be 30% of your homes total power capacity just for changing EV. You wouldn't be able to run AC and the dryer and charge an EV at the same time at that rate. But more importantly there is only so much power at the pole.

They might not burst into flames, today, but these technologies weren't invented because there was no risk.

> That would be 30% of your homes total power capacity just for changing EV

That's the thing - most people have a 8 to 12 hour window to fully charge their car(s) overnight and when you and your neighbors are using practically no energy. Worst case is there is no active management and there is just a new peak at midnight. Best case is that the electric company incentivizes you to not only charge at non-peak times, but also pays you to allow them to manage the charging times.

This technology is not science fiction - it already exists. I got a $250 rebate from my electric company to install a connected level 2 charger. It is not currently managed, but if there is some dystopian future where all of my neighbors aren't burning hydrocarbons, all have EVs, and somehow the infrastructure hasn't kept up, as long as my car is fully charged in the morning, I don't care if it happened from midnight to 2 AM or 4 AM to 6 AM.

But also...

> Most homes have 100 amp service

Most homes built decades ago, maybe. And to be clear, we're talking about US 120V system. I would be very surprised if any house built since...lets be generous...the 1980s doesn't have a 200A supply or couldn't easily be updated.

Your recommendation would require updates to the NEC to even be considered.

As it stands today, an EV charger (or an outlet designated for EV charging) is considered to be 'in use' 100% of the time from a loading perspective (i.e., when counting how big of a main breaker you need to handle). Which, honestly, makes sense. You can't predict when other loads are being used reliably, and you can use an EV charger for many hours. For, say, during the middle of the night.. there's a high heating load so that loading will happen simultaneously.

There are more intelligent ways to handle this (and, the products exist today!), however they're quite expensive. Maybe less expensive than a full new overhaul of your house's electrical... but eventually electrical needs to be updated to code.

Also, regarding 100A vs 200A main panels: it heavily depends on the size of the house. I know in my neighborhood, which the oldest house was built in 2008, they only gave 100A panels to houses that were ~1700sqft or smaller. For larger houses, those got 200A panels.

It seems that this 100/200A thing might just be very different across even just North America, nevermind Europe. So much so that we can't make a general statement either way.

As in no, it does not heavily depend on size in general in the way you describe. It may do so where you are but that's about it. My house is smaller than 1700sqft, was built quite some years before 2008 and we have a 200A panel and I don't know what I would do with 100A service. It would be impossible actually. But that might be because we use electric baseboard heating and thus lots of heating circuits with quite a bunch of amps in use by that.

All houses in this neighborhood use natural gas for heating and stove/oven heating, so they have minimal heating load in the winter in terms of actual electrical consumption, and you get rid of the 50A oven outlet.

In general, electric heat is a bit of a menace in terms of electrical consumption... especially given electric prices lately.

When I moved into my home the first major upgrade I did was upgrading my electrical panel. The home was built in the early 80's and had a 100amp panel.

Putting in a 200 amp panel ran me about $1,000. Power company checked off on it and upgraded my meter in the process. I also added a 240v 30amp socket in the garage for things like an EV, and put a whole house surge protector on in the process.

My house has rock solid power at every socket and plenty of capacity for the future as well, definitely worth the investment.

> GFCI and AFCI are great! But a home isn't going to burst into flames or explode without them. Which is why there are exemptions.

True, but not what you said. You said the changes are not safety related, but these are safety related.

Keep in mind 240v @ 30 amps = charging at 30 miles per hour or so. Common daily driving (12k miles a year) = 33 miles per day. Even throttling to 10 amps (which my charger supports), is 11 miles per hour or 110 miles per day if you charge for 10 hours.

Having had a 100 amp service, it was really not a big deal. Sure I'd normally charge at 11pm, when the AC wasn't running. But the home is using WAY less electricity than when I bought in 1994 when TVs consumed a ton of power, single paned windows insulated poorly, a fair number of 300 watt halogen bulbs, and tons of the 100 watt incandescents. Between LED lighting, a more efficient refrigerator, and a MUCH lower power flat panel TV our power use per day is less than it was in 1994, even with a EV.

100 amps @ 240v is a ton of power, and if you need to peak shave there's quite a bit of room between 240v@30 amps and 240v@10 amps which is plenty for most normal driving patterns.

240 at 20A is sufficient for an overnight charge for nearly all uses of EV cars and SUVs. So even less impact.

Also a device is available that shares the EV circuit with a dryer circuit; set your car to start charging very late at night when laundry is not running. Zero additional max load for the house.

>It sounds like most of the upgrades are about convenience to the power company. Not anything safety related

It's always painful trying to have discussions related to any kind of physical infrastructure on HN because it's absolutely full of people that assume that physical design and maintenance is somehow the trivial, easy part.

This is why American infrastructure is crumbling. People are under the impression that concrete, pipes lasts forever, but it doesn't.
> That's not necessarily true. It sounds like most of the upgrades are about convenience to the power company. Not anything safety related, which is why older properties are exempt.

The exterior service disconnect rule added in 2020 is safety related, it’s so firefighters can kill electrical power to a home from the outside to make it safe to enter. It has nothing to do with the utility.

I keep hearing that, it seems like no big deal. The average annual driving I hear is somewhere around 12,000 miles. 12,000/365 = 33 miles a day. Or 10 ish hours on a 120v circuit. Presuming most people sleep, shower, dress, etc 10 ish hours a day it doesn't seem like a big deal. Sure you might have to occasionally use an external charger ... much like the gas folks do.

33 miles a day of electricity is not that much, something like 7.6 KwH per day. For perspective AC units use from 0.5 to 5 KwH per hour.

Is it a difference, yes. However most EVs charge off peak, and would go even more off peak with a financial incentive. I set mine to start charging at 11pm when it's the cheapest rate, which nicely offsets AC use which is heaviest in the afternoon.

that is interesting to consider a neighborhood scale of infrastructure and the capabilities therein. How much copper is underground in various places, is fiber internet present or on the way, something to think about for sure.