What Every Homeowner Should Know About Derated EV Chargers
Derated EV Chargers: What Homeowners Need to Know Before Installing L2 Charging
Questions to ask your electrician so you actually get fast charging
A friend recently texted me, thrilled to finally have reliable at-home charging. With the purchase of their second EV, they upgraded from a Level 1 (L1) charger, the kind that plugs into a standard outlet, to a Level 2 (L2) charger.
They’d been blowing fuses once they added the second car, and the old L1 setup barely met their needs even with one EV. So the upgrade felt like a big deal.
Then he told me their new charging speed: 12 miles per hour.
My reaction: Wait…what? Only 12?
That didn’t sound like much of an upgrade.
He assured me it was better than the 2 miles per hour he and his wife were getting before. Still, L2 charging should typically deliver 25–30 miles per hour, not less than half that.
So what happened?
Derating: The Hidden Reason Your “Fast Charger” Isn’t Fast
It turns out their electrician had derated (slowed down) the charger.
This is more common than most homeowners realize.
Electricians derate an EV charger to meet National Electrical Code (NEC) requirements for “continuous loads.” An EV charger counts as a continuous load because it can run at full power for three hours or more.
To be clear: the electrician is doing this to follow the rules and meet NEC compliance, but homeowners often don’t understand what they’re losing in the process. Derating can mean your EV might not fully recharge overnight.
Here’s the rule that drives everything:
The 80% Rule: A circuit must be rated for at least 125% of the charger’s demand.
If your panel doesn’t have enough capacity when the electrician does the load calculation, they’ll derate the charger to keep it within code, reducing charging speed along the way.
So yes, my friend did upgrade to L2…but the upgrade didn’t deliver the performance they expected.
How Load Management Unlocks Fast Charging Without a Panel Upgrade
Here’s the good news: You most likely already have enough power in your home. You just need to use it more intelligently.
A load management device like the Stepwise Tap makes your existing electric panel smart. It sits between the panel and the EV charger and automatically controls power to high-energy devices like EV chargers.
The result?
✅ Your charger runs at full speed, with the Stepwise Tap slowing down the charger slightly only if it is going to go over the limits.
✅ Your home stays within code
✅ You protect your panel from overload
✅ You save thousands of dollars and the hassle of a full panel upgrade
Because the Stepwise Tap adjusts to keep overall panel usage within limits only when needed, homeowners get optimal L2 speeds all of the time — exactly what they thought they were buying in the first place
Questions to Ask Your Electrician Before Installing an EV Charger
To make sure you get the performance you’re expecting, ask:
“What charging speed (miles per hour) will I actually get?”
“Are you planning to derate the charger to meet code?”
“If we use a load manager like the Stepwise Tap, how much faster could it charge?”
And if you’d like a second opinion, our team can do a free electric panel review and help you understand your options.
Get the Performance You Expect. Don’t Settle for Less
As more people buy EVs and install chargers for the first time, it’s essential to ask the right questions—especially if you want real L2 charging and not a slowed-down version of it.
A little education goes a long way toward getting the charging experience you paid for.
Include “free electric panel review” in the comments when you reach out