LeftieBiker
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Re: A tale of two chargers

Thu Apr 22, 2021 10:20 pm

I kinda sorta get the intent of wanting to allow multiple 15 Amp outlets on a 20 Amp wire/breaker, but I *don't* understand why these '15 Amp' receptacles are actually rated for 20 Amps. Does a 20 Amp load on the circuit place a 20 Amp load on each receptacle ?
No. They are likely rated for 20 amps because surge loads for motors starting up can hit that, and because it makes more sense to have one basic design that can handle the higher load.
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goldbrick
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Re: A tale of two chargers

Fri Apr 23, 2021 9:22 am

I'd agree that the reason the receptacles are rated for 20A is that the basic design (probably as cheap as can be....) easily supports 20A and as Leftie said, why make 2 different versions when 1 version will cover any situation.

As for the loads, any single receptacle could pull 20A or even more. Or several receptacles could each pull, say, 10A or any combination of the above. The idea is that the breaker will trip and prevent more than 20A being carried by the wire since it is only rated for that amount. How the various loads add up doesn't matter as long as the total is less than 20A.

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Re: A tale of two chargers

Fri Apr 23, 2021 10:14 am

goldbrick wrote:
Fri Apr 23, 2021 9:22 am
I'd agree that the reason the receptacles are rated for 20A is that the basic design (probably as cheap as can be....) easily supports 20A and as Leftie said, why make 2 different versions when 1 version will cover any situation.

As for the loads, any single receptacle could pull 20A or even more. Or several receptacles could each pull, say, 10A or any combination of the above. The idea is that the breaker will trip and prevent more than 20A being carried by the wire since it is only rated for that amount. How the various loads add up doesn't matter as long as the total is less than 20A.
Which is why we have one receptacle design no matter the Amp load. We just rely on the breaker.

Oh wait ... never mind.
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jjeff
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Re: A tale of two chargers

Fri Apr 23, 2021 10:21 am

SageBrush wrote:
Fri Apr 23, 2021 10:14 am
goldbrick wrote:
Fri Apr 23, 2021 9:22 am
I'd agree that the reason the receptacles are rated for 20A is that the basic design (probably as cheap as can be....) easily supports 20A and as Leftie said, why make 2 different versions when 1 version will cover any situation.

As for the loads, any single receptacle could pull 20A or even more. Or several receptacles could each pull, say, 10A or any combination of the above. The idea is that the breaker will trip and prevent more than 20A being carried by the wire since it is only rated for that amount. How the various loads add up doesn't matter as long as the total is less than 20A.
Which is why we have one receptacle design no matter the Amp load. We just rely on the breaker.

Oh wait ... never mind.
The 20a receptacle just guarantees the wiring going to the outlet is 12g and it has a 20a breaker, it's for devices the mfg knows it needs to be able to supply more than 12a continuously. You should never see a 20a outlet on a 15a circuit but you could see a 15a outlet on a 20a circuit.
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SageBrush
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Re: A tale of two chargers

Fri Apr 23, 2021 10:44 am

jjeff wrote:
Fri Apr 23, 2021 10:21 am
SageBrush wrote:
Fri Apr 23, 2021 10:14 am
goldbrick wrote:
Fri Apr 23, 2021 9:22 am
I'd agree that the reason the receptacles are rated for 20A is that the basic design (probably as cheap as can be....) easily supports 20A and as Leftie said, why make 2 different versions when 1 version will cover any situation.

As for the loads, any single receptacle could pull 20A or even more. Or several receptacles could each pull, say, 10A or any combination of the above. The idea is that the breaker will trip and prevent more than 20A being carried by the wire since it is only rated for that amount. How the various loads add up doesn't matter as long as the total is less than 20A.
Which is why we have one receptacle design no matter the Amp load. We just rely on the breaker.

Oh wait ... never mind.
you could see a 15a outlet on a 20a circuit.
A 15 Amp receptacle ... rated for 20 Amps. Which would be fine, until multiple such receptacles are on the same circuit.

Sorry, but this does not make sense and it is not coherent or consistent. Manufacturers have adapted by using the 20 Amp plug if their device pulls more than 12 Amps. They are smartly ignoring the too high Amp rating of the most basic 120 Volt, 15 Amp receptacle.
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goldbrick
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Re: A tale of two chargers

Fri Apr 23, 2021 12:14 pm

My guess is that a 20A receptacle is meant to signify that it is attached to a 20A circuit and as such will allow a 20A appliance to be plugged into it.

A 20A (or 15A) circuit with multiple 15A receptacles is the norm in US households. The circuit breaker protects the circuit if more than 15A is pulled through the circuit.

A 15A receptacle on a 20A circuit isn't an issue. A 20A receptacle on a 15A circuit is an obvious code violation.

LeftieBiker
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Re: A tale of two chargers

Fri Apr 23, 2021 1:07 pm

Here the norm is 15A wiring and breakers for normal household outlet/lighting circuits, and 20A for "small appliance" circuits, which are not supposed to have lights on them, only outlets. That was originally to stop the larger appliances from blowing light bulbs when they start up.
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johnlocke
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Re: A tale of two chargers

Fri Apr 23, 2021 1:43 pm

SageBrush wrote:
Thu Apr 22, 2021 9:48 pm
johnlocke wrote:
Thu Apr 22, 2021 1:23 pm
SageBrush wrote:
Fri Apr 16, 2021 2:53 pm
I'm confused. Are you saying that all circuits with 15 Amp breakers have 20 Ampacity wire ?
No. I'm saying that even 15A outlets are actually rated for 20A. You still need 12g wire to carry 20A legally. If you use 14g wire you are limited to a 15A breaker. 12g wire is used sometimes when several rooms are wired to one breaker. Best practice is one breaker for each room but that requires a lot more wire and the time to string it. Cheaper to use 12g wire and wire in several rooms to one breaker. Typically done for bedrooms and small bathrooms. Living room/dining room on one breaker is common as well.
Thanks for the explanation

I kinda sorta get the intent of wanting to allow multiple 15 Amp outlets on a 20 Amp wire/breaker, but I *don't* understand why these '15 Amp' receptacles are actually rated for 20 Amps. Does a 20 Amp load on the circuit place a 20 Amp load on each receptacle ?
Let's assume that you have a 20A breaker wired to outlets with 12g wire. You have a 15A outlet with an extension cord with a 1500w space heater, a 200w reading light and a 200w laser printer plugged in to the extension cord. you can run any 2 of the 3 devices without exceeding 15A. if you run all 3 at once though, you're at 15.8A but below the 20A limit on the breaker. If your outlet is really rated at 15A, it's overloaded but the breaker doesn't protect it. That's why the outlet is really rated at 20A current even though the outlet is not supposed to carry more than 15A. If some idiot does something stupid and overloads the 15A outlet, the outlet can still safely carry the load. The extension cord is another problem altogether.
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SageBrush
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Re: A tale of two chargers

Fri Apr 23, 2021 2:11 pm

johnlocke wrote:
Fri Apr 23, 2021 1:43 pm
get the intent of wanting to allow multiple 15 Amp outlets on a 20 Amp wire/breaker, but I *don't* understand why these '15 Amp' receptacles are actually rated for 20 Amps. Does a 20 Amp load on the circuit place a 20 Amp load on each receptacle ?
Let's assume that you have a 20A breaker wired to outlets with 12g wire. You have a 15A outlet with an extension cord with a 1500w space heater, a 200w reading light and a 200w laser printer plugged in to the extension cord. you can run any 2 of the 3 devices without exceeding 15A. if you run all 3 at once though, you're at 15.8A but below the 20A limit on the breaker. If your outlet is really rated at 15A, it's overloaded but the breaker doesn't protect it. That's why the outlet is really rated at 20A current even though the outlet is not supposed to carry more than 15A. If some idiot does something stupid and overloads the 15A outlet, the outlet can still safely carry the load. The extension cord is another problem altogether.
[/quote]
Thanks -- I get it.

Overloading the circuit with multiple loads forces NEC to match receptacle and breaker ampacities.
2013 LEAF 'S' Model with QC & rear-view camera
Bought Jan 2017 from N. California
Two years in Colorado, now in NM
03/18: 58 Ahr, 28k miles
11/18: 56.16 Ahr, 30k miles
09/20: 54.3 Ahr; 38k miles
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Wavebender
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Re: A tale of two chargers

Sun Apr 25, 2021 9:37 pm

OP here, with an update.

We tested our 50 amp outlet today with our modified Nissan EVSE and it ROCKS! We took a battery at 66% to 100% in under two hours and probably less (we were watching TV and being lazy as we just had our second Phizer shots yesterday and felt a little blah.)

As soon as we plugged it in, we heard two chimes instead of the usual one, and heard a soft clunk from under the hood that doesn’t happen when we use 120v “granny” mode. Level 2 engaged, captain!

$175 for the EVSE and a couple hundred for the 50 amp circuit installation by a licensed electrician. I call that a bargain.
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