[WunderWagen]

We purposely had a hardwired EV charger (Wallbox Pulsar+) added to the OUTSIDE of our home to facilitate charging in the driveway. Not trusting large battery packs inside the home.

 

[whitex]

The Emporia manual says it “requires a dual-pole, dedicated breaker at 60A+ for a 48A charge or 50A+ for a 40A charge.” Since it’s saying 50A+ why wouldn’t 60A work?

The issue with a 60A breaker is not the Emopria EVSE, it's the NEMA 14-50 in between the breaker and the EVSE. Breaker is supposed to protect the circuit, meaning the wiring and the outlet. Even if the wiring is 60A capable, but the outlet is 50A capable, the breaker has to be 50A, and EVSE has to be set to draw no more than 40A (80% of the circuit max). If you remove the outlet and hardwire the EVSE, you can use 60A breaker and set the EVSE to 48A max.

 

[getmoving]

We purposely had a hardwired EV charger (Wallbox Pulsar+) added to the OUTSIDE of our home to facilitate charging in the driveway. Not trusting large battery packs inside the home.

And then packrats will gnaw the charger wire and burn your house down anyway.

 

[RMSko]

I now understand and I don’t think this is an issue with my setup. My EVSE Emporia charger only outputs 40A when it is plugged in. It won’t output 48A unless it is hardwired (it’s built that way). If I’m understanding this correctly, as long as it only outputs 40A there shouldn’t be a problem, is that right?

 

[getmoving]

I now understand and I don’t think this is an issue with my setup. My EVSE Emporia charger only outputs 40A when it is plugged in. It won’t output 48A unless it is hardwired (it’s built that way). If I’m understanding this correctly, as long as it only outputs 40A there shouldn’t be a problem, is that right?

As long as everything is working as it should, there shouldn't be a problem. The electrical codes are developed to give protection even when things don't operate as they should.

One risk would be if the charger malfunctioned and drew more power than it should, the outlet might melt before the circuit breaker shut things down. And that might start a fire. I'm not saying that is likely to happen.

Another risk is if the property were inspected for any reason, an inspector might flag the issue. That is more likely if you sell the home or have major renovations done.

 

[whitex]

Based on your explanation, our GFCI installed breaker protects only the section of the circuit up to the Nema 14-50. As stated by Getmoving, this requirement would not be applicable to a direct wire charger. Hence, for a plug-in charger, we would require the GFCI, which is currently mandatory for all installations, irrespective of the manufacturer's specifications, unless otherwise mentioned in the installation requirements.

GFCI is actually meant to protect between the NEMA 14-50 outlet and the EVSE, against things like touching the plug prongs by accident, or having a longer wire from the outlet to the EVSE cut by accident (since it is exposed and not mounted to anything as it is a plugin). If it is in the breaker, it protects the line between the breaker and the outlet too, but that is already supposed to be protected from ground faults by being hardwired. This is why a NEMA 14-50 GCFI outlet instead of the breaker would also satisfy the code GCFI requirement, just like for kitchen or bathroom outlets you can use either a GFCI breaker or GFCI outlets - the cabling between the breaker and hardwired outlet does not need GFCI protection.

I would appreciate it if you could provide me with some documented evidence or the owner's manual showcasing that the Audi 40amp travel charger includes a GFCI and the specific installation parameters prior to the recall.

That is part of the SAE J1772 specification which applies to all J1772 EVSE's. The spec is not free (J1772_201710: SAE Electric Vehicle and Plug in Hybrid Electric Vehicle Conductive Charge Coupler - SAE International), but if you Google it you can find plenty of documentation/presentations talking about it. To reiterate, this GFCI only protects the cable between the EVSE and the car, it will not trip if you drive over a cable between the outlet and the EVSE, damage that cable, then touch it and get electrocuted (that is what the GFCI in the breaker or outlet is supposed to protect against).

The box that was melted had a continuous load rating of 60 amps, which is why I find it surprising that it melted so quickly.

If the box was rated for 60A continuous, and if it was behind a 60A breaker, and the wiring was rated for 60A continuous, that means something failed its rating. Either:

• The breaker allowed more than 60A continuous
• The box failed/melted at 60A or less
• There was a bad or loose connection which generated a lot of heat
• The wiring insulation was only rated for 75C or less rather than 90C and the combined heating from Audi plug and hot weather for example, cause the insulation to fail.
• The box was rated for 60A continuous but only at regular ambient temps - if the Audi plug heated up the wires to 165F, perhaps that was sufficient for the box to fail, which in turn cause the connections to fail and generate even more heat which melted the box

My guess is the last one.

 

[whitex]

The Emporia manual says it “requires a dual-pole, dedicated breaker at 60A+ for a 48A charge or 50A+ for a 40A charge.” Since it’s saying 50A+ why wouldn’t 60A work?

Again, what the manual tells you here only applies if you hardwire. You cannot connect a NEMA 14-50 outlet to a 60A breaker, since NEMA 14-50 outlets or plugs are only rated for 50A (40A sustained). The outlet is your weak point (again, assuming the wiring is 60A capable, given that the installer connected a 60A breaker to a NEMA 14-50, I am starting to doubt your installers expertise). If you want to charge at 48A, I would:

1. double check that the wiring in in fact capable of 60A in the conduit it's in - typically AWG6 90C rated wire running by itself in a conduit (so 2 live wires plus ground, with ground either AWG6 or AWG8 as it can be smaller)
2. eliminate the NEMA 14-50 outlet - hardwire the Emporia
3. keep the 60A breaker

If you really want an outlet, and to charge at 48A, you need to swap out the NEMA 14-50 outlet with a NEMA 14-60 outlet, which also means you need to swap out the plug on the Emporia (they are similar looking plugs, but you cannot plug in NEMA 14-50 plug to a NEMA 14-60 outlet). Also, double check the wiring capabilities as per above. Also, you will probably be required to use a GFCI breaker for the NEMA 14-60 outlet, with hardwire solution you do not.

 

[getmoving]

The Emporia could also be hardwired and run at 40A, unless it won't allow that for some reason. I think I threw 48A charging into the mix. But given other oddities it would still be prudent to check the capacity of the wiring.

 

[whitex]

I now understand and I don’t think this is an issue with my setup. My EVSE Emporia charger only outputs 40A when it is plugged in. It won’t output 48A unless it is hardwired (it’s built that way). If I’m understanding this correctly, as long as it only outputs 40A there shouldn’t be a problem, is that right?

If your Emporia came with the NEMA 14-50, then it assumes it's on a 50A circuit, hence it only draws 40A. Your breaker should be 50A not 60A for this setup. Wiring needs to be 50A+ capable.

 

[RMSko]

If your Emporia came with the NEMA 14-50, then it assumes it's on a 50A circuit, hence it only draws 40A. Your breaker should be 50A not 60A for this setup. Wiring needs to be 50A+ capable.

The Emporia lets you pick what the circuit is, i.e., either 50A pr 60A. The manual tells you to select 50A if it is plugged in, even if it's a 60A breaker. This way it will only draw 40A. I've now looked into it a bit more and it appears irrelevant if the breaker is 60A even with a 14-50 outlet as long as you tell Emporia that it's 50A, i.e., the charger actually contemplates a 14-50 plug with a 60A breaker.

 

[JNealCox]

The Charging unit has no idea what size the breaker is. It's up to you to be smart, and size the breaker accordingly, or dumb, and use an over-sized breaker.

 

[RMSko]

The Charging unit has no idea what size the breaker is. It's up to you to be smart, and size the breaker accordingly, or dumb, and use an over-sized breaker.

All due respect this is not correct. There is a specific option in the Emporia charger where you tell the charger the size of the breaker and based on what you say, the charger outputs either 40A or 48A.

 

[JNealCox]

All due respect this is not correct. There is a specific option in the Emporia charger where you tell the charger the size of the breaker and based on what you say, the charger outputs either 40A or 48A.

But YOU are telling that to the charger. There is no way for the charger to sense that, so it is a far from foolproof method,.

 

[whitex]

The Emporia lets you pick what the circuit is, i.e., either 50A pr 60A. The manual tells you to select 50A if it is plugged in, even if it's a 60A breaker. This way it will only draw 40A. I've now looked into it a bit more and it appears irrelevant if the breaker is 60A even with a 14-50 outlet as long as you tell Emporia that it's 50A, i.e., the charger actually contemplates a 14-50 plug with a 60A breaker.

A 60A feeding a NEMA 14-50 will not pass electrical inspections in most places. You might never see a problem with your setup, but you can have problems should the car be faulty/break and draw more current than advertised, should the EVSE be faulty/break and advertise the wrong current. I've been driving EVs for over a decade, 6 EVs to date (2 at a time), have yet to see a car draw more (though all cars were decently new) but have seen one EVSE break and advertise the wrong values. If that happens, the EV or EVSE manufacturer will say that your breaker was supposed to be properly sized and protect your circuit even if their product malfunctions, and they'd be right - this is supposed to be a swiss-cheese model where more than one protection needs to fail for bad things to happen. Insurance company will probably agree as that will save them having to pay for your damages, and if your house catches on fire and damages neighboring properties, those owners will likely sue you too. If this was a licensed electrician you paid for a complate install, who got the required permit and passed inspection, it will be on him and the inspector, but if you paid some guy under the table, it's on you. You using a too large breaker is similar to not using a breaker at all and just counting on main home breaker to pop should there be a short, but still risking a fire if there is too much current being drawn.

A non-gfci 50A breaker is under $15 in some cases (example). At least it will prevent fires, you're reducing the risk to just electrocution when handling the plug or something going wrong with the plug and/or wire and someone being exposed to it. A GFCI is a more expensive, ~$100 (example), which is still not much compared to risking anything that could happen, no matter how small. However, given GFCI can conflict with EVSE's GFCI, why not just hardwire the darn EVSE, get 48A instead of 40A and peace of mind.

Your circus, your monkeys, your life, your money, your risk, though technically your fire might affect your neighbors unless you live alone on a larger property. If you ever try to sell a house you'll have to replace the breaker (50A with GFCI) anyways if the buyer gets a thorough inspector.

 

[getmoving]

All due respect this is not correct. There is a specific option in the Emporia charger where you tell the charger the size of the breaker and based on what you say, the charger outputs either 40A or 48A.

ChargePoint does it the same way. It’s just their way of applying the 80% “de-rating” of the circuit for continuous load. I found it a bit confusing, actually.

But this also illustrates the problem with having an oversize breaker on the circuit. A human makes the setting, and some future human might speed-read the Emporia instructions, see a 60A breaker, and make the corresponding setting on the EVSE. Now the EVSE and car will draw 48A continuous through a NEMA 14-50 outlet that may not be up to the task.

And it wouldn’t necessarily fail right away. It might wait until the owner is taking advantage of cheap middle-of-the night charging rates…

 

[JNealCox]

My situation is the opposite. When the electrician installed my 50A house 14-50 plug circuit for me to use with Audi EVSE, he installed a 40A breaker. He said that, even though the house circuit had to be increased due to "continuous use", the breaker still should not exceed the rating of the device on the circuit (40A EVSE). Made sense to me--after all, the risk from "continuous use" is not that more amps are suddenly going to start flowing, it is that the circuit might warm up too much over time. I've used it for over 4 years with no problem.

 

[whitex]

The Charging unit has no idea what size the breaker is.

Well, they do know because either:

1. Installer told the EVSE of the circuit size by setting appropriate dip switch or software setting at installation time
2. The plug pigtail has signaling which tells the EVSE what plug is being used, and EVSE looks up maximum current for said plug - Audi charger does this, as to Tesla Mobile Connectors and other vendors of portable/pluggable EVSEs.

 

[JNealCox]

Well, they do know because either:

1. Installer told the EVSE of the circuit size by setting appropriate dip switch or software setting at installation time
2. The plug pigtail has signaling which tells the EVSE what plug is being used, and EVSE looks up maximum current for said plug - Audi charger does this, as to Tesla Mobile Connectors and other vendors of portable/pluggable EVSEs.

But, again, that is only because someone set things up in advance. You could go and change the breaker to whatever you liked and the EVSE would not have a clue.

 

[whitex]

But, again, that is only because someone set things up in advance. You could go and change the breaker to whatever you liked and the EVSE would not have a clue.

Correct. EVSE does not detect the breaker size. Some EVSE detect the plug type, and electrical code mandates the breaker size for a matching outlet. So an EVSE with a NEMA 14-50 plug will draw max 40A assuming 50A circuit, it plugs into a NEMA 14-50 outlet, and that outlet must be protected by a 50A breaker.

 

[whitex]

My situation is the opposite. When the electrician installed my 50A house 14-50 plug circuit for me to use with Audi EVSE, he installed a 40A breaker. He said that, even though the house circuit had to be increased due to "continuous use", the breaker still should not exceed the rating of the device on the circuit (40A EVSE). Made sense to me--after all, the risk from "continuous use" is not that more amps are suddenly going to start flowing, it is that the circuit might warm up too much over time. I've used it for over 4 years with no problem.

Actually a 40A circuit connected to a NEMA 14-50 is a bad idea. It has actually started fires in the past (2013 Toronto, Canada IIRC), causing Tesla to change their Mobile Connectors to 32A max (initially they did it via software update, then redesigned the Mobile Connectors to be only 32A). Here is why this is bad:

1. 40A residential breaker itself is typically rated at 80%, or 32A, sustained load. Pushing 40A through it over hours and hours can cause it to fail
2. 40A breaker often indicates 40A max wiring. Again, 40A residential wiring is rated for 80% sustained load, so 32A max.
3. When the 40A circuit with 40A breaker is connected to a 50A outlet, such as NEMA 14-50, the EVSE which plugs into it will assume a 50A circuit, therefore draw 40A continuously. Unfortunately this coincides with the max breaker current, which means the breaker will not trip, meaning 40A, which is 100% load for 40A wiring, will be running through the wiring

It can work for a long time, but:
a) this is against most electrical codes
b) when it works, you have no safety margin, which is what this 20% headroom is supposed to provide

The reason Tesla went with 32A Mobile EVSE (no controls on it to throttle it) is to avoid the above situation where the circuit and the breaker connected to an outlet is sized at 80% of the outlet max. Since 32A breakers are uncommon, they are unlikely to run into a situation where a Tesla EVSE will overload the circuit. A common size may be 30A (my dryer plug at my home is on a 30A circuit and breaker), but if I was to plug in my Tesla Mobile Connector to it, it would draw 32A, which could cause the breaker to trip - danger avoided.

Bottom line is this, if your wiring is sized for 50A, you should put a 50A breaker on it. If your wiring is only sized for 40A, leave the breaker at 40A but get an EVSE which can only charge at 32A max (i.e. tell the EVSE that it's on a 40A breaker).