Home charging planning

[Eclipso]

Hey there folks! My Model 3 has been ordered for a week and I am thinking about home charging installation.

I have done some research and googlin' but I am not totally confident in what I need and / or if it will work so here I go:

* Main box has 150 amp main breaker, 2 slots still open (next to each other) installing a 50 amp dual breaker

* Run is going to be 100 feet of 6/3 NM-B (sadly 125 feet since they don't see it in hundred feet runs)

*Nima 14-50 outlet

Any help is appreciated, really would rather not have to put out a ton of cash for someone to do it for me.

 

[tjkessler]

That sounds like it would work out fine. You'll need to buy an adapter for the Tesla portable charger as it doesn't come with the 14-50 any more. Btw amazon will sell you 100' run of 6/3.

 

[Gamsberry]

There are other threads here that discuss the importance of buying a quality 14-50 receptacle. I had already bought a leviton from Home Depot when I read them and ordered a bryant 9450FR (Amazon) . The difference in construction is amazing. The Bryant is going in the wall, the leviton went into the trash.

 

[rjt!]

The choice of circuit size and socket depends on the charger you are going to use and (surprisingly enough) the car you are going to charge. Model 3 standard can only AC charge at 32 amps - they have only two 16 amp AC to DC power supplies in them, so you need only 40 amp service for most wall boxes. The Model 3 LR and the Model S and X have 3 power supplies - so they can benefit from 60 amp service to charge at 48 amps. A hardwired Tesla charger can support up to 100 amp service, delivering 80 amps of AC charging power shared across multiple wall boxes, and you set the configuration during installation via a (little tiny!) rotary switch inside the box. So you can charge something with a lot more capability than an M3 if you wanted.

Given the limitations of power plugs and receptacles, I don’ know that you can get much beyond 40 amp service delivering 32 charging amps - it would depend on the specific charger you have. My new M3 was a replacement for a Leaf and we had the AeroVironment L2 30 amp charger on 40 amp service, we’ replaced it with a Tesla wired charger to get those last two amps and avoid using the adapter. Shouldn’t have bothered, I guess, but we did.

Sounds like 50 amps is either more than you need if you have an M3 standard(not necessarily baboon thing, oversized breakers have their risks), or not as much as you could use if you have an M3 LR or better - assuming you have a hardwired wall box or one with a suitable plug. Copper conductor size is a straight up lookup of current vs. distance... I don’t have that at hand so can’t comment on that. IMHO, thicker is better, I hate ‘at the margin’ setups.

 

[Eclipso]

Initially its just going to be the portable (with purchasing the additional plug)

Doing some additional reading looks like I might need to run UF cable since it will be going outside for @5 feet or so before going into the basement and then into the garage. Safe assumption ill need to run that through conduit?

 

[KenC]

Conduit? An outdoor box? I bought the Eaton enclosure from HD that includes a NEMA 14-50 receptacle. Both HD and Lowes have the same one. Obviously the wiring is the most expensive part. Make sure your double-pole breaker matches the others in the box.

 

[Nogasmn]

For that long of a run I would suggest going to 4 gauge wire. I made the mistake and purchased, off amazon, 4/3 romex for my install. If I had to do it over again I would have purchased two lengths of 4 AWG wire and one length of 6 AWG wire, for the ground. All the wire can be purchased at Lowes. I assume you will be running it in underground conduit PVC is fine to use with what I have suggested.

 

[brkaus]

Might I suggest you include a photo of your breaker box?

And a more detailed description of where the wire will go?

Sounds like your breaker box is outside with the empty slots.

You intend to run a short piece of conduit from the box down to the basement?

From there, you plan on going through the house. Exposed? Ceiling?

Then into garage perhaps? Inside a wall? Finished or not?


You are allowed to run Romex in a conduit for short distances for purposes like this in many jurisdictions - it's kinda up to the inspector.

 

[Timbo2]

Buy the Gen 2 NEMA 14-50 adapter now if this is the way you decide to charge.

Availability and shipping times are all over the map with charging cable adapters when purchased by mail. Otherwise pick one up at the service center.

 

[Eclipso]

So its going from this outside box down into the basement (unfinished) then from the basement into the garage into a wall mounted Nema, nothing fancy. Literally the only outside portion is potentially this, I might be able to fish it through the existing tube but its pretty full.

I plan on buying an adapter at the service center when I go,

 

[brkaus]

What's coming through that tube right now? Romex or THNN?

 

[Plu1357]

This is what I have done.

1. Purchased a Tesla Wall Connector.
2. Run 6/2 Romex wire for more than 100ft. If you use NEMA 14-50, you have to use 6/3 wire. Tesla WC does not use neutral.
3. Install 60A breaker to my 200A panel.

(Just a reference. not a tutorial)

 

[eprosenx]

Hey there folks! My Model 3 has been ordered for a week and I am thinking about home charging installation.

I have done some research and googlin' but I am not totally confident in what I need and / or if it will work so here I go:

* Main box has 150 amp main breaker, 2 slots still open (next to each other) installing a 50 amp dual breaker

* Run is going to be 100 feet of 6/3 NM-B (sadly 125 feet since they don't see it in hundred feet runs)

*Nima 14-50 outlet

Any help is appreciated, really would rather not have to put out a ton of cash for someone to do it for me.

As discussed here, make sure to get a good quality receptacle. The Bryant is my favorite price/performance wise, but the Hubbell is probably the best (same company that makes Bryant). Then Cooper may also make a decent one Tesla recommended.

Lots of options of where to source wire from. I buy mine from Home Depot for simple projects like this. Any electrical supply house can hook you up. A friend of mine also likes these guys: https://www.wireandcableyourway.com

Can you post more pictures of your panel? I want to see the stickers on the door with all the gory technical details. Optimally, pictures with the cover panel off are helpful too if you can do this safely. Also, take pictures of the path to the place you plan to install this and the final place of install.

That sounds like it would work out fine. You'll need to buy an adapter for the Tesla portable charger as it doesn't come with the 14-50 any more. Btw amazon will sell you 100' run of 6/3.

You can also do a 6-50 instead of a 14-50 as others have mentioned. The neutral is totally unused in charging Tesla's at 240v/208v (or any EV for that matter).

There are other threads here that discuss the importance of buying a quality 14-50 receptacle. I had already bought a leviton from Home Depot when I read them and ordered a bryant 9450FR (Amazon) . The difference in construction is amazing. The Bryant is going in the wall, the leviton went into the trash.

Precisely. ;-)

Given the limitations of power plugs and receptacles, I don’ know that you can get much beyond 40 amp service delivering 32 charging amps - it would depend on the specific charger you have. My new M3 was a replacement for a Leaf and we had the AeroVironment L2 30 amp charger on 40 amp service, we’ replaced it with a Tesla wired charger to get those last two amps and avoid using the adapter. Shouldn’t have bothered, I guess, but we did.

Sounds like 50 amps is either more than you need if you have an M3 standard(not necessarily baboon thing, oversized breakers have their risks), or not as much as you could use if you have an M3 LR or better - assuming you have a hardwired wall box or one with a suitable plug. Copper conductor size is a straight up lookup of current vs. distance... I don’t have that at hand so can’t comment on that. IMHO, thicker is better, I hate ‘at the margin’ setups.

You can draw 40 amps on a NEMA 14-50 or 6-50 receptacle if you have sufficient gauge wire and a 50a breaker (40a is 80% of 50a since you have to derate it). As others have mentioned, the UMC Gen 2 that comes with the car is limited to 32a. But UMC Gen 1 units and other manufacturers of EVSE units can charge at the full 40a.

I would not be worried about any wire size that meets the minimum code requirements and that is installed properly. The code calculations are intentionally very conservative.

Initially its just going to be the portable (with purchasing the additional plug)

Doing some additional reading looks like I might need to run UF cable since it will be going outside for @5 feet or so before going into the basement and then into the garage. Safe assumption ill need to run that through conduit?

Hrm, very good callout. This is a very good point. Wire in conduit outside is always considered a wet location and NM cable (which has paper inside of it) is not considered acceptable for wet locations.

You are allowed to run NM cable (romex) in conduit, but it is a bit goofy (sometimes it is just what needs to be done).

Trying to do the entire run in UF due to that 5' would suck. You totally can do THHN/THWN-2 in conduit and that is rated for wet (hence the W in THWN-2).

Might I suggest you include a photo of your breaker box?

And a more detailed description of where the wire will go?

Sounds like your breaker box is outside with the empty slots.

You intend to run a short piece of conduit from the box down to the basement?

From there, you plan on going through the house. Exposed? Ceiling?

Then into garage perhaps? Inside a wall? Finished or not?


You are allowed to run Romex in a conduit for short distances for purposes like this in many jurisdictions - it's kinda up to the inspector.

Yes, more pictures would be great!

Note that I am a huge fan of conduit if you can figure out a way to do it. I ran my Wall Connector wiring in 3/4 in EMT conduit and ran 6 AWG copper inside of it with a #10 ground. 60a breaker, lets me do 48a to the car. In your case, you could do this and then put a 50a breaker since it can't be over the receptacle rating. For your run it may be a lot more work though.

So its going from this outside box down into the basement (unfinished) then from the basement into the garage into a wall mounted Nema, nothing fancy. Literally the only outside portion is potentially this, I might be able to fish it through the existing tube but its pretty full.

I plan on buying an adapter at the service center when I go,

Note that there are all sorts of requirements about if you have to run the wire through studs, or you can run it below the studs (if over a certain size), etc... Check these out before you run the cable! I forget the rules on 6 AWG.

Congrats on the new car! Please report back on your solution!

 

[Eclipso]

Running a bit behind today so ill have to catch up and will gladly post a few additional pics but quickly, I am using this chart to decide what wire to run

https://www.cerrowire.com/wp-content/uploads/2018/09/voltagedrop091418.pdf

ill gladly purchase a better receptacle, I opted against the mounted tesla wall unit initially since its 500$ that I don't necessarily want to spend right now and I am sure there are other 3rd party solutions that for around the same price will work all the same and will plug right in.

Day 7 and still no "car paired to my order" as of now Waiting sucks. ill have some time tomorrow after work to grab some additional pics and post them up.

 

[Chetanh]

Our local store does not stock NEMA adapters. I was told not all stores stock them. If that is the case then, make sure you order it online well in advance. My order was screwed up by fedex and it took 15 days to deliver. Luckily i had a J1772 outlet at work.

 

[saltsman]

Lots of good advice here - especially from eprosenx. The NEC can get complicated in the details of a complicated run like this. A good electrician can help if you get too confused.

Switching from 6/3 for a NEMA 14-50 to 6/2 for a NEMA 6-50 can save you a few bucks in a long run like this. 14-50 is more versatile, but not sure you would ever need the neutral in the future or not. I ran 6/2 personally. The advice to get a quality receptacle is a good one. Don't cheap out there.

IMHO, don't worry that much about charging at more than 32 Amps. My experience is 32 is more than enough for overnight charging for a Model 3 at 30 miles of range per hour. You don't have a lot of overhead with your 150 Amp service panel anyway. Sure, you could install a 60Amp circuit, but 32 Amps on a 50 Amp circuit still works great and required nothing more than a $35 Mobile Connector adapter (e.g. 14-50, 6-50, etc.)

The only thing that caused me any concern is why your panel has so many tandem breakers but still has two empty slots. I'd make sure those slots are in good shape. It's been my experience that electricians will typically use up all available free space before switching to more expensive tandem breakers. It's odd to see those still empty. My $0.02.

Enjoy the ride!

 

[eprosenx]

Running a bit behind today so ill have to catch up and will gladly post a few additional pics but quickly, I am using this chart to decide what wire to run

https://www.cerrowire.com/wp-content/uploads/2018/09/voltagedrop091418.pdf

ill gladly purchase a better receptacle, I opted against the mounted tesla wall unit initially since its 500$ that I don't necessarily want to spend right now and I am sure there are other 3rd party solutions that for around the same price will work all the same and will plug right in.

Day 7 and still no "car paired to my order" as of now Waiting sucks. ill have some time tomorrow after work to grab some additional pics and post them up.

So voltage drop is really not often a factor in residential EV charging installation. It would really only be a factor in very long runs. I should also call out that voltage drop limits are not mandated by the NEC, they are only highly encouraged. So EV's actually don't really have an issue if voltage is low, they can take it just fine. The key with the Tesla's is that the voltage drop is not so high as to kick in its throttling mechanism for safety (which in the case of a really long electrical run is not a safety issue, but it can't tell the difference between that and a dangerously bad connection).

That document is not the perfect thing for this use case since EV's must only draw 80% of the circuits capacity (so basically you have to oversize the circuit capacity wise by 125%). So if you use 6 AWG Romex (NM cable) on a 50a circuit, you can only draw a max of 40a (the UMC Gen 2 by default only does 32a). But let's say you had a EVSE that drew 40a since I would always assume that if installing a 14-50 (for future). That document you linked to gives a different answer than the same companies online web calculator and the app from them on my phone. It says a 200' run would need 4awg for a 40a load in that document, but the online calculator says 6 awg copper can do 203' at 3% voltage drop (the NEC recommendation).

So basically, unless you are installing over a 200' run, 6 awg copper is the ticket for a NEMA 14-50.

This is the chart you actually care about (well technically it is a specific table in the NEC, but this is a duplication of that basically):
Ampacity Charts - Cerrowire

For NM-B (romex) you have to use the 60c limit. For THHN in conduit you can use the 75c limit.

Optimally you would do this install all in conduit, but that may be way too much work. You could do Romex, but then technically you are not supposed to put that in conduit outside (though if you used proper water tight fittings on EMT conduit for just that few feet I wonder if anyone would care). You could do THHN in conduit to a junction box in the crawl space, and then switch to romex from there (but that is another splice point that is something to fail). UF does not really feel right either for this application...

 

[carl_o]

Your circuit breaker Ampere rating should 25% more than your charger AC output Ampere rating. You should assume that any home charger should be expected to charge for more than three hours.

The National Electrical Code (Article 210.20) requires the rating of the overcurrent device (circuit breaker or fuse) to be 125 percent of any load where the maximum current is expected to continue for three hours or more.

This means your 40 Amp charger needs to be on a 50 Amp breaker. This is to reduce nuisance tripping. Standard circuit breakers will trip if a load larger than 80% of the breaker rating is applied for more than three hours. A 32 Amp charger needs to be on a 40 Amp breaker.

 

[eprosenx]

Your circuit breaker Ampere rating should 25% more than your charger AC output Ampere rating. You should assume that any home charger should be expected to charge for more than three hours.

The National Electrical Code (Article 210.20) requires the rating of the overcurrent device (circuit breaker or fuse) to be 125 percent of any load where the maximum current is expected to continue for three hours or more.

This means your 40 Amp charger needs to be on a 50 Amp breaker. This is to reduce nuisance tripping. Standard circuit breakers will trip if a load larger than 80% of the breaker rating is applied for more than three hours. A 32 Amp charger needs to be on a 40 Amp breaker.

A few things to add to this:

• Not only must the breaker be 25% larger but also the wire itself must be 25% larger to go with that larger breaker.
• The NEC explicitly defines all EV charging as a "continuous load", so the expectation of three hours or not does not matter in this case (but yes- that would otherwise be the rule to apply).
• You don't really know exactly when a thermal-magnetic breaker is going to open. That is why they have this requirement for continuous loads needing to be only 80% of a breakers/circuits capacity since you just really don't know at what amperage it will open. Breakers are tested "in free air" (no surrounding breakers) at 104 degrees Fahrenheit and expected not to open under therir rated load. But when you put in surrounding breakers it is easy to get above 104 degrees.

 

[carl_o]

I purchased from Amazon (Cost $120) (https://www.amazon.com/gp/product/B00A8FQUZQ/) and highly recommend the Siemens TL17US panel that includes a NEMA 14-50R 50 Amp receptacle in a weatherproof enclosure for outdoor installations. I use this with the Tesla Mobile Connector (Mobile Connector) that came with my Model 3. The charge speed is 30 miles of range per hour of charge for a Model 3.

Siemens product literature: https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_49451