NEMA 14-50 plug or wall charger?

[eddieb3]

I just put in an order for the M3 LR RWD and am now trying to figure out which charging option to go with in my garage. I was starting to lean towards the 14-50 plug since it's cheaper than the wall charger and almost as high on charge miles per hour. But then I ran across the fact that the mobile charger cable now included with the M3 is limited to 32 amps (Gen 1 was 40 but Gen 2 is only 32) and thus can't take advantage of the 40 amps the 14-50 plug can get. The wall charger can do 48 amps which is the max for the M3 LR and 50% higher than what I can get with the mobile charger cable and a 14-50 plug.

I then thought maybe I just get another cable that can handle 40 amps, but that cable costs as much or more than the wall charger which can give me 48 amps. So now I'm thinking of going with the wall charger as a result. I sometimes may need to fully charge overnight from a day where I take the charge pretty low. Also, I can get a plan with my electric company that gives me .09 cents per Kw between midnight and 6 AM, but would be 2.5x - 6x times higher otherwise depending on time of day and season, so getting a full charge in 6 hours is important.

Do I have all this right and thus my choice of wall charger makes sense? What might I be missing here? Thanks all.

 

[SSonnentag]

Yeah, I'd do whatever it takes to get a full charge during that 9-cent window of opportunity.

 

[nwdiver]

I just put in an order for the M3 LR RWD and am now trying to figure out which charging option to go with in my garage. I was starting to lean towards the 14-50 plug since it's cheaper than the wall charger and almost as high on charge miles per hour. But then I ran across the fact that the mobile charger cable now included with the M3 is limited to 32 amps (Gen 1 was 40 but Gen 2 is only 32) and thus can't take advantage of the 40 amps the 14-50 plug can get. The wall charger can do 48 amps which is the max for the M3 LR and 50% higher than what I can get with the mobile charger cable and a 14-50 plug.

I then thought maybe I just get another cable that can handle 40 amps, but that cable costs as much or more than the wall charger which can give me 48 amps. So now I'm thinking of going with the wall charger as a result. I sometimes may need to fully charge overnight from a day where I take the charge pretty low. Also, I can get a plan with my electric company that gives me .09 cents per Kw between midnight and 6 AM, but would be 2.5x - 6x times higher otherwise depending on time of day and season, so getting a full charge in 6 hours is important.

Do I have all this right and thus my choice of wall charger makes sense? What might I be missing here? Thanks all.

You can get a HPWC with a pigtail and plug that into a 14-50 to get 40A. I definitely recommend having a plug. IMO it's worth having the versatility and backup. If you decide to get a Hardwired HPWC it shouldn't cost that much more to get a 14-50 installed too while the wall and panel are open.

 

[1.21GW]

Hardwire HPWC. I was going to do the plug and essentially it was very similar cost for the installation between HPWC and NEMA14-50. Plus i can always take my HPWC with me if i move.

With your narrow window for $0.09, it seems prudent to get the max amps.

 

[ronm2948]

With the NEMA, you will get about 30 miles / hour or 180 miles per evening during your cheap electricity window. The HPWC will get 44 miles / hour or so, or about 264 miles per evening. My guess is that 180 will be more than enough most of the time, and having a NEMA does give more flexibility.

That being said, I decided to go with the HPWC, and my electricity is the same price all day. I personally liked the possiblity of charging at the full 48A whenever I might need it.

 

[GaryW]

Welcome to the forum.

To me, a question that matters is how much do you drive?

If you drive less than 180 miles on an average day, either solution should offer the same benefit.

The 32A on a 14-50 plug with the included cable should provide 30 miles of range per hour for a model 3.

During your 6 hour window, that would give you 180 miles of range per day.

Best of luck with your choice, and your car! Please post pictures!

 

[SSonnentag]

I've been driving electric for about 3 years now, and have gone from using a 110V outlet at 8A all the way up to my current setup with dual 72A-capable HPWCs. I normally leave my charge rate set to 40A in the car, but it is good to be able to charge more quickly when the need arises, and it does arise occasionally. If you can afford it, and your electrical panel can support it, more amps is always better.

 

[P85_DA]

+1 for Wall Connector

 

[eprosenx]

You can get a HPWC with a pigtail and plug that into a 14-50 to get 40A. I definitely recommend having a plug. IMO it's worth having the versatility and backup. If you decide to get a Hardwired HPWC it shouldn't cost that much more to get a 14-50 installed too while the wall and panel are open.

FWIW, I do not think this is likely to be a code compliant installation.

Refer to NEC 2017 Article 625. (free access with registration)

NFPA 70®: National Electrical Code®

I think it is pretty obvious that the HPWC is intended to be "Fixed in Place" and so the only wiring option listed is hard wiring.
If you can make the argument that it is "Stationary Equipment" then there is the option of a cord, but it can only be a max of 12 inches. I do not think the HPWC falls into this category however since it requires tools to mount/unmount.

Also, per NEC you must follow manufacturers installation instructions which in the case of the HPWC clearly tell you to hard wire it in.

I should also call out that I recently discovered 625.54 where they tucked in (last minute in an emergency change to NEC 2017) that all EVSE charging receptacles must be GFCI protected (even like 50a ones). So that makes installing NEMA 14-50's MUCH more expensive (like an extra $100 if you can even find a breaker). This clause was news to me and so I am researching it some more. Some states modify the code (Oregon has specifically struck some of the GFCI requirements in other sections, but they missed this one I think). I don't think most folks realize it got added (electricians and inspectors alike). I have only heard of a couple folks reporting that they were required to do this by an inspector.

GFCI is not required on a hard wired Wall Connector since the Wall Connector itself has built in GFCI.

As others have mentioned, putting a HPWC on a 14-50 or 6-50 cord would limit you to 40a of charging capacity vs 48 amp (or more up to 80a depending on how you wire it and what car you have).

 

[TexasEV]

The OP said getting a full charge in 6 hours is important. That’s not the right way to look at it. It’s unlikely you would ever need to fully charge the battery in one night. In 6 hours you’re adding 180 miles range to what is already in the battery. Unless you need more than 180 miles range per day, every day, you’ll do just fine with a NEMA 14-50 outlet charging at 32A. Even if you had to charge for an additional hour (an additional 30 miles) occasionally it would be much less expensive than buying a Wall Connector.

 

[nwdiver]

FWIW, I do not think this is likely to be a code compliant installation.

Refer to NEC 2017 Article 625. (free access with registration)

NFPA 70®: National Electrical Code®

I think it is pretty obvious that the HPWC is intended to be "Fixed in Place" and so the only wiring option listed is hard wiring.
If you can make the argument that it is "Stationary Equipment" then there is the option of a cord, but it can only be a max of 12 inches. I do not think the HPWC falls into this category however since it requires tools to mount/unmount.

Also, per NEC you must follow manufacturers installation instructions which in the case of the HPWC clearly tell you to hard wire it in.

I should also call out that I recently discovered 625.54 where they tucked in (last minute in an emergency change to NEC 2017) that all EVSE charging receptacles must be GFCI protected (even like 50a ones). So that makes installing NEMA 14-50's MUCH more expensive (like an extra $100 if you can even find a breaker). This clause was news to me and so I am researching it some more. Some states modify the code (Oregon has specifically struck some of the GFCI requirements in other sections, but they missed this one I think). I don't think most folks realize it got added (electricians and inspectors alike). I have only heard of a couple folks reporting that they were required to do this by an inspector.

GFCI is not required on a hard wired Wall Connector since the Wall Connector itself has built in GFCI.

As others have mentioned, putting a HPWC on a 14-50 or 6-50 cord would limit you to 40a of charging capacity vs 48 amp (or more up to 80a depending on how you wire it and what car you have).

.... how do stoves and dryers get away with it?

 

[eprosenx]

.... how do stoves and dryers get away with it?

They are covered under different code sections. This code section is article 625 which is specific to EVSE’s.

There is very specific wording around stoves and ovens.

But yeah, from a practical standpoint I suspect pigtails are not an issue. Just a code issue.

 

[nwdiver]

But yeah, from a practical standpoint I suspect pigtails are not an issue. Just a code issue.

I wonder if that's where all the HPWCs with pigtails came from... maybe Tesla thought they could change the code. I bought a HPWC with a pigtail off ebay. I haven't seen them in a while. Got a great deal. 4 for $1200.

 

[tga]

I wonder if that's where all the HPWCs with pigtails came from... maybe Tesla thought they could change the code. I bought a HPWC with a pigtail off ebay. I haven't seen them in a while. Got a great deal. 4 for $1200.

It's more about an NEC requirement to follow the manufacturer's installation instructions. Dryers and ranges are intended to be plugged in. The HPWC that comes with a pigtail is clearly intended to be plugged in. The "normal" HPWC is not (directions say to hardwire).

 

[nwdiver]

It's more about an NEC requirement to follow the manufacturer's installation instructions. Dryers and ranges are intended to be plugged in. The HPWC that comes with a pigtail is clearly intended to be plugged in. The "normal" HPWC is not (directions say to hardwire).

So I guess that WOULD be an NEC compliant option... if you can find a HPWC built with a pigtail...

or a clipper creek...

 

[ewoodrick]

I just put in an order for the M3 LR RWD and am now trying to figure out which charging option to go with in my garage. I was starting to lean towards the 14-50 plug since it's cheaper than the wall charger and almost as high on charge miles per hour. But then I ran across the fact that the mobile charger cable now included with the M3 is limited to 32 amps (Gen 1 was 40 but Gen 2 is only 32) and thus can't take advantage of the 40 amps the 14-50 plug can get. The wall charger can do 48 amps which is the max for the M3 LR and 50% higher than what I can get with the mobile charger cable and a 14-50 plug.

I then thought maybe I just get another cable that can handle 40 amps, but that cable costs as much or more than the wall charger which can give me 48 amps. So now I'm thinking of going with the wall charger as a result. I sometimes may need to fully charge overnight from a day where I take the charge pretty low. Also, I can get a plan with my electric company that gives me .09 cents per Kw between midnight and 6 AM, but would be 2.5x - 6x times higher otherwise depending on time of day and season, so getting a full charge in 6 hours is important.

Do I have all this right and thus my choice of wall charger makes sense? What might I be missing here? Thanks all.

Stop with the range anxiety. Just look at how many miles you will drive on an average day and see if it will charge in the timeframe. For MOST people, you don't need the HPWC and for a LOT of people, even the 14-50 can be overkill.
I'm charging my Model 3 on a 14-50 and my 2018 Leaf on 120V. Neither one really ever worries about being charged.

 

[eprosenx]

I wonder if that's where all the HPWCs with pigtails came from... maybe Tesla thought they could change the code. I bought a HPWC with a pigtail off ebay. I haven't seen them in a while. Got a great deal. 4 for $1200.

Yeah, I have wondered the same. I don't trust anything off eBay. I am guessing those pigtails were added 3rd party?

Note that Tesla does not make the HPWC. It is made by some Chinese company, so perhaps somehow some units slipped out the back door? (I forget the name of the company - I found it at one point - perhaps via their UL rating data or something)

Or maybe the pigtail units were just for some tradeshow use or something and not certified?

 

[nwdiver]

Yeah, I have wondered the same. I don't trust anything off eBay. I am guessing those pigtails were added 3rd party?

Note that Tesla does not make the HPWC. It is made by some Chinese company, so perhaps somehow some units slipped out the back door? (I forget the name of the company - I found it at one point - perhaps via their UL rating data or something)

Or maybe the pigtail units were just for some tradeshow use or something and not certified?

Nope; Clearly made with the 14-50 pigtail. UL and everything... The HPWC are unique units. They have the same dial for changing the pilot signal but if you try to go >40A it errors out the HPWC. The cable that connects to the car is also the thinner UMC-type cable not the thicker HPWC cable, which is kinda nice for garage use; Definitely designed for ~40A.

 

[eprosenx]

Nope; Clearly made with the 14-50 pigtail. UL and everything... The HPWC are unique units. They have the same dial for changing the pilot signal but if you try to go >40A it errors out the HPWC. The cable that connects to the car is also the thinner UMC-type cable not the thicker HPWC cable, which is kinda nice for garage use; Definitely designed for ~40A.

Oh wow! Fascinating!!! Do you have any pictures? I am going to see if I can go figure out what the company name was now.

That would be cool if Tesla sold those.

Oh btw, Tesla may not give a crud about what NEC says about their Wall Connectors since at least if it is a plug in device, I did not think NEC applied? Only UL? (random devices are not NEC rated right - they are UL rated)

 

[nwdiver]

40A HPWC; love to know why Tesla never sold them....