[Analemma_]

Does this distinction also apply at the lower amps of ordinary 12V plugs? I frequently trickle-charge my EV from an ordinary 12V outlet outside on the porch for 14 hours or more, is that going to be a problem?

(EDIT: sorry, yes, I meant 120V outlet)

[darknavi]

I assume you mean 120v outlet, but IMO yes.

One good test that I saw somewhere that I do on new outlets I am charging on, is leave the car charging for ~30 minutes and then quickly unplug the charger from the wall. Touch the prongs to your hands. If they are very warm or hot, you are likely over-drawing that outlet and need to ramp down your amperage draw (or better yet, find a new outlet).

This article focuses on outlets but the wiring is just as (or more) important and outlets can very easily be installed with under-code wiring.

[abakker]

Yes - likely moreso. (I'm assuming you meant 120v plugs, like US residential.)

The issue in the circuit ampacity for standard residential outlets - typically, a 120v 15 amp plug will be wired in 14 gauge NM-B wire (romex), which already de-rates the maximum temperature the wire jacketing is allowed to reach over higher ampacity wire (THHN) which is typically run in conduit. For a given wire gauge, THHN has more ampacity and the jacket is rated to a higher temperature.

for a 20amp 120v circuit (not common unless you install intentionally for that purpose) you need 12 gauge wire.

But, as mentioned in the article, continuous loads need to be up-sized because of temperature, and even standard outlets for the correct ampacity circuit don't often anticipate 100% duty cycle.

BUT, the real question is for your trickle charger, how many amps does it draw? if it tries to draw 12 amps on a 15amp circuit, everything is fine. If it tries to draw 15-20 amps on a 15 amp circuit, there is some danger. Many breakers (esp older ones) will not actually pop if the amp demand ramps up slowly.

Ampacity Charts: https://www.cerrowire.com/products/resources/tables-calculat...

Source: I've wired a LOT of power tools with big loads, but I am not an electrician. Take this advise as indicative and decide whether it warrants you contacting an electrician to validate your situation.

[bryanlarsen]

Car chargers only pull 12A from a 15A circuit.

[abakker]

Yeah - you'll see that I mentioned that - if that is true, then great. But, IMO, it's worth verifying. Even more worth double checking if the building is old, or an extension cord is involved.

[LUmBULtERA]

It's definitely true on a Tesla using their mobile charger. The car will report on its screen exactly what it's charging at. When I charged at 120v (before getting a hardwire charger installed), the car reported charging at 12 amps.

[bryanlarsen]

Yes, the one time I used an extension cord to charge the car, I set the max amperage to 8 even though it was a 15Amp rated cord.