Tesla HPWC 50A Aluminum wiring

  • SUPPORT THE SITE AND ENJOY A PREMIUM EXPERIENCE!
    Welcome to Tesla Owners Online, four years young! For a low subscription fee, you will receive access to an ad-free version of TOO. We now offer yearly memberships! You can subscribe via this direct link:
    https://teslaownersonline.com/account/upgrades

    SUBSCRIBE TO OUR YOUTUBE CHANNEL!
    Did you know we have a YouTube channel that's all about Tesla? Lots of Tesla information, fun, vlogs, product reviews, and a weekly Tesla Owners Online Podcast as well!

x-cimo

Active member
Joined
Aug 9, 2018
Messages
37
Location
Gatineau
Tesla Owner
No
Country
Country
#1
Hello everyone,

So... almost two years ago I got 3 NEMA 14-50 50A outlets install at my house. Two of which are located outside.
They all connect to a subpanel in my garage feed by a 100A link to my 200A main panel.
100A is 1AWG ALuminum
50A (14-50) are 6AWG ALuminum.

I've now figure out that two permanent HPWC outside would be much better, since pulling out and plugging the protable charger everyday will be a pain, especially in the winter.

I've found older thread which state that Tesla only recommand Copper wire. However, when reading the manual it seems like Tesla is less categorical on the subject.

Tesla's official documentation state the following:
"NOTE: For most branch circuits of 100A, use 3 AWG (26.7 mm2), 75°C (167°F) copper wire. For installations less than 100A, use conductors that are sized according to local electrical codes."

and at the bottom of this page there is mention of AL wiring (CU-AL) : https://image.ibb.co/khQGOA/hpwc.png

If I was performing a new install, I would go with Copper, however in my current situation, am I reading this right and for a low amp installation such as mine (50A), Aluminum wiring would still follow telsa's user manual?

If that matters, I am located in Canada and this is to charge two LR Model 3.

Thanks
 

garsh

Dis Member
Moderator
TOO Supporting Member
Joined
Apr 4, 2016
Messages
12,711
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#3
6AWG aluminum has a resistance of 0.648 Ω/1000ft.
8AWG copper has a resistance of 0.6405 Ω/1000ft.
That's pretty comparable.

8 gauge copper romex is typically recommended for 50-amp circuits, at least if they're not too long.

So, I don't think you need to replace your wiring.
Disclaimer: I'm not a licensed electrician.

References:
Aluminum Wire Characteristics
Copper Wire Characteristics
 

Karl Sun

Well-known member
Joined
Sep 18, 2018
Messages
348
Location
home
Tesla Owner
Model 3
Country
Country
#4
I think the issue is the small size of the screw-down terminals that accept the wire in the HPWC. I installed 6 AWG copper and it did fit, but it is a PITA to make the bends to the terminals. Thicker aluminum would be more difficult to bend and fit ino the holes..
 

JML

Well-known member
Joined
Jul 26, 2018
Messages
201
Location
Broomfield, Colorado
Tesla Owner
Model 3
Country
Country
#7
I am not a licensed electrician, and I am not your licensed electrician. I do however own two properties that are plagued with aluminum wiring.

You should be able to pigtail some 8AWG copper wire to the existing 6AWG aluminum wire. If you can get wire nuts good for 6AWG, then you can coat the wires in anti-oxidant, twist them together, and put on the nuts. That's how my install was done, but it was only 10AWG. There are other options to attach two wires, such as screw down lugs. It might be best to hire a professional to do the install if you have any doubts, but you won't have to pull new wires in any case.
 

iChris93

Moderator
Moderator
TOO Supporting Member
Joined
Feb 3, 2017
Messages
2,306
Location
Ann Arbor, MI
Tesla Owner
Model 3
Country
Country
#8
I am not a licensed electrician, and I am not your licensed electrician. I do however own two properties that are plagued with aluminum wiring.

You should be able to pigtail some 8AWG copper wire to the existing 6AWG aluminum wire. If you can get wire nuts good for 6AWG, then you can coat the wires in anti-oxidant, twist them together, and put on the nuts. That's how my install was done, but it was only 10AWG. There are other options to attach two wires, such as screw down lugs. It might be best to hire a professional to do the install if you have any doubts, but you won't have to pull new wires in any case.
Why would this be better then just using the aluminum wires?
 

garsh

Dis Member
Moderator
TOO Supporting Member
Joined
Apr 4, 2016
Messages
12,711
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#10
Why would this be better then just using the aluminum wires?
Some connectors are designed for aluminum wires, and some are not. If the installation manual for the new wall charger says to only use copper, then we must assume that it is the latter.

@JML is presenting a solution that doesn't involve replacing all of the wiring. As I noted, the 6g aluminum wiring should be able to handle the same load as 8g copper, so the wiring itself should be fine with that load.
 

ER1C8

Active member
Joined
Jan 1, 2018
Messages
114
Location
Rhode Island
Tesla Owner
Model 3
Country
Country
#11
Wire connectors must be designed to work with aluminum wires. If they are not, you can get oxidation which increases resistance and heat and can eventually cause a fire. The wall connector is not designed for aluminium wire. I would not use it with them.

If I were you, I'd get the appropriate size outlet (approved for aluminium wire) for your aluminum wires ameperage then attach a plug to the wall connector. That is of course if local code allows you to have a detacable plug on an EVSE.
 
1

13004

Guest
#12
8 gauge copper romex is typically recommended for 50-amp circuits, at least if they're not too long.
I realize that this an Al wire thread but.....

NOOO.......argh! The ampacity for 8 ga. NM-B is only 40 amps!

A Gen II MC with a 32A max rating deploying the included 14-50 adapter can be wired on a 40A branch circuit with a minimum of 8 ga. Romex on a 2-pole 40A breaker.

A Gen I UMC with a 40A max rating (US only) deploying the included 14-50 adapter must be wired on a 50A circuit with a minimum of 6 gauge Romex or #8 (in conduit) THHN/THWN and deploying a 2-pole 50A breaker.

Always check your local electrical codes and seek out information from your local electrical inspector and never take advice from forum members such as myself.
 
Last edited by a moderator:

garsh

Dis Member
Moderator
TOO Supporting Member
Joined
Apr 4, 2016
Messages
12,711
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#13
NOOO.......argh! The ampacity for 8 ga. NM-B is only 40 amps!
Ampacity is defined as the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Circuit breakers should be sized so that the maximum continuous current is 80% of the capacity, which would be a 50 amp breaker in this case. Is my understanding mistaken?

https://en.wikipedia.org/wiki/Ampacity
 

Feathermerchant

Top-Contributor
Joined
Sep 17, 2018
Messages
594
Location
Euless, Tx
Tesla Owner
Model 3
Country
Country
#14
The key here is temperature rating. That is not the rating of the conductor material but the rating of the insulation. When you look at a chart you will see different ampacity for different insulation types.

In addition the ratings change for free air vs in conduit and how many conductors in what kind of conduit. That part is all about heat transfer.