50 amp vs 40 amp vs 30 amp

[emoore]

Just because you can do it, it doesn’t make it safe. I wouldnt charge at 48 amps on a 50 amp breaker. Just playing with fate.

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[Zoidz]

Just because you can do it, it doesn’t make it safe. I wouldnt charge at 48 amps on a 50 amp breaker. Just playing with fate.

Yeah, NEC establishes the codes based on extensive test data and science. Sometimes it seems overly conservative. But sooner or later an edge case occurs, and that's where it makes the difference between safety and a fire. Pictures like this should be enough to prove the point.

 

[Joe schmoe]

Why in the world would you charge an EV with a portable generator at home? Defeats the purpose of an EV.

I’ve had four power outages since July ranging from 10 hours to over three days.

There is very limited public charging infrastructure near my house, and what there is is often not working, especially in the aftermath of a storm with widespread outages in the city.

I’ve contracted an electrician to install a large, fixed generator, but they are several months out on installations due to demand.
.

that portable generator has the capacity to charge the Rivian enough to support my normal driving, as well as my critical house loads indefinitely, along with a portion of the HVAC. The fixed generator will run the household but not support level 2 charging of the Rivian at the same time.

The reasons are debatable, but the electric grid is increasingly unreliable. We used to literally go -years- between outages, now losing power for half a day or more occurs at least once a month.

 

[emoore]

I’ve had four power outages since July ranging from 10 hours to over three days.

There is very limited public charging infrastructure near my house, and what there is is often not working, especially in the aftermath of a storm with widespread outages in the city.

I’ve contracted an electrician to install a large, fixed generator, but they are several months out on installations due to demand.
.

that portable generator has the capacity to charge the Rivian enough to support my normal driving, as well as my critical house loads indefinitely, along with a portion of the HVAC. The fixed generator will run the household but not support level 2 charging of the Rivian at the same time.

The reasons are debatable, but the electric grid is increasingly unreliable. We used to literally go -years- between outages, now losing power for half a day or more occurs at least once a month.

Yeah that sucks. Mine is pretty reliable and only getting better. Ever think about solar with battery backup?

 

[BCondrey]

60 Amp breaker, charge at 48A, one car at a time. I get 25 miles an hour like that. My wife and I share the charger between my R1T and her Tesla M3.

Do not cheap out on the setup of your charger. You will thank us later.

 

[BCondrey]

I’ve had four power outages since July ranging from 10 hours to over three days.

There is very limited public charging infrastructure near my house, and what there is is often not working, especially in the aftermath of a storm with widespread outages in the city.

I’ve contracted an electrician to install a large, fixed generator, but they are several months out on installations due to demand.
.

that portable generator has the capacity to charge the Rivian enough to support my normal driving, as well as my critical house loads indefinitely, along with a portion of the HVAC. The fixed generator will run the household but not support level 2 charging of the Rivian at the same time.

The reasons are debatable, but the electric grid is increasingly unreliable. We used to literally go -years- between outages, now losing power for half a day or more occurs at least once a month.

We just had a $15K Generac installed for this very reason. The grid sucks where we live and we have used the generator twice in the last two months. It powers the house the EV charger, the AC, everything. Comparable battery-based systems would have cost us 2x as much.

 

[Cstond151]

Something to keep in mind as well are the requirements for EV charger installation rebates. I’m in California and in order to qualify for a $500 installation rebate the amperage can not exceed 40. Obviously not something to completely base your decision on but worth considering

 

[TollKeeper]

So help someone that has very little knowledge of wiring. The knowledge I have about wiring is limited to.. I made sure my house was wired in copper and not aluminum when I bought it.

The electrician I talked to about getting a drop installed for when I get a charger is talking about using SER 2-2-2-4 aluminum wire.

The reason he gave is that copper wire here is in high demand due to the housing boom that is currently going on. And the cost to install copper vs aluminum will cost about double, or more.

Is the SER going to work?

 

[jjswan33]

So help someone that has very little knowledge of wiring. The knowledge I have about wiring is limited to.. I made sure my house was wired in copper and not aluminum when I bought it.

The electrician I talked to about getting a drop installed for when I get a charger is talking about using SER 2-2-2-4 aluminum wire.

The reason he gave is that copper wire here is in high demand due to the housing boom that is currently going on. And the cost to install copper vs aluminum will cost about double, or more.

Is the SER going to work?

At least with the Rivian charger and the Chargepoint home flex the terminals can receive at most 6 ga wire. I believe they both also say to only use Cu wire. So short answer appears to be no.

 

[emoore]

We just had a $15K Generac installed for this very reason. The grid sucks where we live and we have used the generator twice in the last two months. It powers the house the EV charger, the AC, everything. Comparable battery-based systems would have cost us 2x as much.

Would cost 2x up front but solar panels will save you money in the long term.

 

[SactownD]

I just had this situation and went w the 60A hardwire for the faster speed. Wanted to be sure I could get a full charge when electricity is at its cheapest.

 

[Monkey]

So help someone that has very little knowledge of wiring. The knowledge I have about wiring is limited to.. I made sure my house was wired in copper and not aluminum when I bought it.

The electrician I talked to about getting a drop installed for when I get a charger is talking about using SER 2-2-2-4 aluminum wire.

The reason he gave is that copper wire here is in high demand due to the housing boom that is currently going on. And the cost to install copper vs aluminum will cost about double, or more.

Is the SER going to work?

How long of a run do you have between your electrical panel and charger location? His aluminum wire proposal is fine for running a feed to a new sub panel or disconnect for the charger, then copper from there for the last few feet. These charger units are equipped to take 6 gauge copper.

That said, I don't truly believe you will save money doing it that way unless you're running wire a long distance, like well over 120ft or more. Right now the 6AWG THHN/THWN wire is about $0.85/ft for a single conductor. You need two plus a ground. Ideally, you would just run 3 of those, and color code them black, red and green. The ground wire (green) can be downsized a bit, but you won't save enough money to truly matter. Then run the three wires inside EMT (metallic tubing/ conduit). That probably comes out to about $4.25 -ish per foot. It can also be run as metal clad (MC) cable and that is about $3.80/ft for MC with 2 conductors plus ground.

If you go aluminum 2-2-2-4G, you will have the additional expense of another cabinet and disconnect or breaker setup and the wire is still close to $3/ft. You get an extra conductor as the EVSE only needs the two hots and a ground.

Of course your electrician still has all the labor hours/cost involved installation. 2-2-2-4 aluminum wire is a pain. Running EMT is time consuming...

We have run 6/2 MC cable for our most of our recent charger installs. Except for the ones where the wires/conduit would be exposed, then we run EMT so it's more rigid and cleaner looking. ...I'm not an electrician, but an engineer and general contractor who happens to also manage a bunch of commercial build to suit flex-lease properties.

 

[TollKeeper]

Well the 2-2-2-4 is out... I didnt read the fine print for the Rivian charger only having a lug large enough for a 6.

The run from the outside fuse panel to the side garage is about 40-50 feet (guessing). I would prefer it to be in the front of the garage, so I can park outside if I have a project in the garage. That would add another 20ish feet.

Just a quick search shows a 6-6-6-6 at $1.91 a foot. Code requires a ground and earth. So using my guess of 50 ft, wire is at $95
https://www.lowes.com/pd/Southwire-...r-Service-Entrance-Cable-By-the-Foot/50333145

Where as the same in copper is $300 as a spool
https://www.lowes.com/pd/Southwire-Romex-SIMpull-50-ft-6-3-Non-Metallic-Wire-By-the-Roll/50188983

or
at $6.98 a foot = $349
https://www.lowes.com/pd/6-3-UF-Wire-By-the-Foot/3345390

Both cases would require a conduit.

Labor actually isnt to bad. as its all outside the house.. Fuse box to garage. Just have to drill thru the masonry at the garage to feed it into the garage.

Edit:

I do have an additional question. When we say 40 or 50 or 60 amp... Are we talking total amps, or per leg? So for a 40 amp, 20/20 total 40 or 40/40 total 80? I am assuming its the 20/20, but looking for clarification. That might be why the GC was going the aluminum route to run to another breaker box.

 

[Joe schmoe]

Yeah that sucks. Mine is pretty reliable and only getting better. Ever think about solar with battery backup?

I've thought about it, but it's not a good fit for a lot of reasons: The payback with local utility rates (and no local/state incentives) would be more than 30 years, not including the batteries, and enough battery to run my house for more than a day would be prohibitively expensive. I can get a generator to cover me for power outages at maybe 10% of the cost.

We don't have TOU pricing, and rates are well below national averages. I have family in California where it totally makes sense economically, but here it just doesn't.

Also, my lot is full of trees (which I like) and I have almost zero south facing roof space, and no roof space that gets more than an hour or so of direct sun.

Every few years we have someone come to my office (which has a large flat roof and excellent solar exposure) to give us a bid. Nobody has come in at under a 30+ year payback. We'll keep our 80kw Cummins Diesel Generator for the foreseeable future.

 

[emoore]

I've thought about it, but it's not a good fit for a lot of reasons: The payback with local utility rates (and no local/state incentives) would be more than 30 years, not including the batteries, and enough battery to run my house for more than a day would be prohibitively expensive. I can get a generator to cover me for power outages at maybe 10% of the cost.

We don't have TOU pricing, and rates are well below national averages. I have family in California where it totally makes sense economically, but here it just doesn't.

Also, my lot is full of trees (which I like) and I have almost zero south facing roof space, and no roof space that gets more than an hour or so of direct sun.

Every few years we have someone come to my office (which has a large flat roof and excellent solar exposure) to give us a bid. Nobody has come in at under a 30+ year payback. We'll keep our 80kw Cummins Diesel Generator for the foreseeable future.

Cool. Hopefully solar makes sense soon or your grid gets more reliable. Diesel is probably going to be much harder to come by in 20 years.

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