Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

6/3 or 6/4?

allj

Member
May 30, 2021
11
0
Massachusetts
Looking at the Gen 3 charger installation guide video it looks like 6/3 cable without a ground is used. Is this correct? Or if it's 6/3 with a ground 6/4? where is the ground hooked up to the charger plate during installation? Picking up my Y next Monday.
Thanks
Alan
 

jcanoe

Active Member
Oct 2, 2020
3,517
3,553
Maryland
Looking at the Gen 3 charger installation guide video it looks like 6/3 cable without a ground is used. Is this correct? Or if it's 6/3 with a ground 6/4? where is the ground hooked up to the charger plate during installation? Picking up my Y next Monday.
Thanks
Alan
6/3 means 6 gauge, 3 conductors. The ground wire is always separate. If you are installing a receptacle such as the NEMA 14-50 then you would need to use 3 conductors plus the ground. If you are installing the Wall Connector then you only need 2 conductors plus the ground wire.

If you are planning to install a 60A circuit for the Wall Connector then, by code, you can only use 6 gauge wire if the wire is other than NM-B (Romex type.) The Tesla install guide is not particularly clear on this. You can use 6 gauge wire such as THHN in conduit or metallic clad (MC) wire but if you are using NM-B wire for the circuit the wire would need to be 4 gauge. 6 gauge NM-B wire should only be used on a maximum of 50A breaker.
 
Last edited:

allj

Member
May 30, 2021
11
0
Massachusetts
Thanks much appreciated. My electrician needs to know this. He was insisting on 3 conductors and a ground. I looked at the install manual. Is 2 conductors and a ground posted anywhere on their site or in a doc?
 

jcanoe

Active Member
Oct 2, 2020
3,517
3,553
Maryland
You can install 3 conductor wiring instead of 2 conductor wire. 3 conductor wire will cost a bit more and would be more difficult to pull through walls and conduit (where required.) 240V hard wired EVSE don't need, don't use the neutral connection so if you ever change to a non-TESLA charging installation you would not need the 3rd wire. If for some reason you wanted the flexibility of a receptacle the NEMA 6-50 does not use the neutral wire.
 

allj

Member
May 30, 2021
11
0
Massachusetts
I thought I had this. I can use the 90 degree rated 6 awg THHN wire in a metal conduit instead of the romex 4awg. However, the installation guide says to use #4 at the terminal block, copper only. Can I disregard this and use the 6 THHN or does the THHN need to be pigtailed with #4awg?? Confused!!

Voltage and WiringNominal 200-240 V AC single-phase
Current Output Range12 – 48 amps
Terminal Blocks12-4 AWG (3.5 - 25 mm2), copper only
Supported Conduit Sizing¾" (21 mm) default, 1" (27 mm) optional
Grounding SchemeTN/TT
Frequency50/60 Hz
 

jcanoe

Active Member
Oct 2, 2020
3,517
3,553
Maryland
I thought I had this. I can use the 90 degree rated 6 awg THHN wire in a metal conduit instead of the romex 4awg. However, the installation guide says to use #4 at the terminal block, copper only. Can I disregard this and use the 6 THHN or does the THHN need to be pigtailed with #4awg?? Confused!!

Voltage and WiringNominal 200-240 V AC single-phase
Current Output Range12 – 48 amps
Terminal Blocks12-4 AWG (3.5 - 25 mm2), copper only
Supported Conduit Sizing¾" (21 mm) default, 1" (27 mm) optional
Grounding SchemeTN/TT
Frequency50/60 Hz
Re: Terminal Blocks. The way I am reading this is depending on your circuit rating (15A up to 60A) you can use any gauge (copper wire only) between 12 gauge wire and 4 gauge.
 

allj

Member
May 30, 2021
11
0
Massachusetts
I apologize I think I was misled by a responding post. The above pic of a prev post was a spec sheet of the charger stating the terminal blocks require 12-4 awg. I don't think it has to be wired by the installer. If it does going from #6 to 12-4 doesn't make sense or does it??
 

jcanoe

Active Member
Oct 2, 2020
3,517
3,553
Maryland
I apologize I think I was misled by a responding post. The above pic of a prev post was a spec sheet of the charger stating the terminal blocks require 12-4 awg. I don't think it has to be wired by the installer. If it does going from #6 to 12-4 doesn't make sense or does it??
It is not stating 12/4 it is stating you can use wire of different gauges varying from 12 gauge all the way to 4 gauge (as long as the wire is made of copper.)
 

allj

Member
May 30, 2021
11
0
Massachusetts
Ok I am learning... So even though the installation guide says the charger can use 6awg 90 degree rated wire (THHN), I can't use this because the breakers are only rated to 75 degrees?? Or can I??
Thank
Alan
 

Geech72

Member
Mar 10, 2021
35
24
NC
Thanks much appreciated. My electrician needs to know this. He was insisting on 3 conductors and a ground. I looked at the install manual. Is 2 conductors and a ground posted anywhere on their site or in a doc?
In my area the difference on a 50 ft roll of Romex between 6-3 and 6-2 is about $20. If it were me I would leave it to the electrician to decide which wire is best; he/she should have the expertise and knowledge of relevant local codes that is needed to make that decision.

From my own install, my father is an electrician and he installed the wall charger with me. We used 6-3 and used the white insulated wire for the ground.
 
Last edited:

jcanoe

Active Member
Oct 2, 2020
3,517
3,553
Maryland
Ok I am learning... So even though the installation guide says the charger can use 6awg 90 degree rated wire (THHN), I can't use this because the breakers are only rated to 75 degrees?? Or can I??
Thank
Alan
According to Google - "Circuit breaker terminals are rated for a maximum temperature of 75 °C. ... Conductors having higher temperature ratings, such as 90 °C, may be used; however, the ampacity must be de-rated to that in the 75 °C column."

The maximum amperage allowed for 6 gauge 90C rated THHN wire is 75A; De-rated for 75C using 6 gauge and non NM-B wire, i.e. THWN, you would be limited to 65A. So you are good to go for using a 60A breaker rated for 75C and 6 gauge 90C rated THHN.
 

Jiver

Member
Dec 30, 2019
59
59
Colorado Springs
I've found this thread very enlightening. I thought that I had done it right but now it is clear that I did not. I originally had an electrician wire up a 20amp circuit for a Clipper Creek LCS-20 charger that I used with a Chevy Volt. At that time I thought that I would buy a Tesla in the future so I had the electrician run 6 gauge wire and told him that I may put a 60amp breaker in there one day. When I bought my M3 three years ago I decided to keep the LCS-20 because even though it was low speed it was fast enough for my daily commute of around 20 miles. If I went farther it would take two night's of charging to get caught up but still was never an issue. I have a Supercharger less than 10 miles from me so my thought was that in the worst case I just needed enough of a charge to make it there. Even after adding a MY I found that the LCS-20 was still fast enough to keep up with the daily driving.

Fast forward to last month when someone gave me a Gen 3 wall charger. I disconnected the LCS-20 and discovered that the electrician had ran both 12/2 romex hooked up to a 20 amp breaker for the LCS-20 and 6/2 romex which was capped and not connected. I disconnected the 12/2, replaced the 20 amp breaker with a 60 amp, wired up the 6/2 romex, and set the Gen 3 charger to 48 amps.

This setup has worked fine for me and my house has not burned down. After reading this thread and doing other research yesterday, though, I reset the Gen 3 to 40 amps and purchased a 50 amp breaker which I will be installing tonight. I never needed the 48 amps and I likely will not need a 40 amp charge rate as I was fine with 16 amps for years. I'd rather that my house did not burn down due to a freak something or other with the wiring. I know that the odds are slim but the code is written how it is for a reason, right? I'll end up with 6/2 romex, 50 amp breaker, and 40 amp charge rate which as near as I can tell gets me code compliant.

Thanks forum.
 
  • Like
Reactions: jcanoe and brinox

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top