HPWC v1 Meltdown

[nwdiver]

Looks like Aluminum Wire! Requirement is #3 copper for 80 amps!!! This is specified in the manual!

The copper barely fits in the lugs. I don't see how you can properly terminate aluminum wire in the HPWC for 80 amps!

Ampacity Charts

Also Aluminum needs to be re-torqued more often than copper, and it tends to get corrosion at the terminations which will overheat if they are pushed to their max. I don't see any anti-corrosion material applied to the terminations (Noalox)

You can use Aluminum Wire... as specified on page 10.

I ran 2-2-2 triplex to my HPWC. 2-2-2 was ~$0.70/ft vs #3 copper is ~$4/ft for 4-strand. For a 70' run I saved ~$200. Everything is outdoors so I'm not worried about a fire I wouldn't run Aluminum wire through walls...

I think I will inspect my HPWC... it's been out there for >3 years now no issues.

 

[Zero CO2]

You can use Aluminum Wire... as specified on page 10.

I ran 2-2-2 triplex to my HPWC. 2-2-2 was ~$0.70/ft vs #3 copper is ~$4/ft for 4-strand. For a 70' run I saved ~$200. Everything is outdoors so I'm not worried about a fire I wouldn't run Aluminum wire through walls...

I think I will inspect my HPWC... it's been out there for >3 years now no issues.

HPWC V2 specifies copper only on page 7 ....hmmmm

 

[nwdiver]

HPWC V2 specifies copper only on page 7 ....hmmmm

Possible that V2 has different lugs. Some lugs aren't compatible with Aluminum due to galvanic corrosion IIRC. You can still use a pigtail. Al=>Al lug=>copper=>HPWC...

Small gauge aluminum wire is a terrible idea but if done correctly there's nothing wrong with large gauge aluminum wire. The wires connecting your house to the pole are almost certainly aluminum.

 

[SageBrush]

but if done correctly

That is the trick, plus I presume the bolt, lug and plate are engineered as a system.

I have never seen a residential electrician use a torque screwdriver. At the high Amp draws of EVs, following installation installations to the letter is important.

 

[nwdiver]

I have never seen a residential electrician use a torque screwdriver.

I've always just use star torque... I torque until I see stars

Aluminum connections are MUCH less forgiving that copper connections... the oxide layer that gives Aluminum it's incredible corrosion resistance also inhibits conduction. With solar PV... Al panels racked on Al rail even with all the surface area are not electrically connected unless you pierce the oxide layer...

 

[SageBrush]

I've always just use star torque... I torque until I see stars

Is my understanding wrong that too much torque can also be a problem ?
I've wondered about twisted cable -- it looks more liable to fray and escape contact.

 

[LargeHamCollider]

Possible that V2 has different lugs. Some lugs aren't compatible with Aluminum due to galvanic corrosion IIRC. You can still use a pigtail. Al=>Al lug=>copper=>HPWC...

Small gauge aluminum wire is a terrible idea but if done correctly there's nothing wrong with large gauge aluminum wire. The wires connecting your house to the pole are almost certainly aluminum.

A high amperage conductor that goes copper-->Aluminum or vice versa usually performs poorly long term, I had to resort to a Cu/Al piece where the two were explosively welded together for a recent job, that stuff isn't cheap.

 

[nwdiver]

Is my understanding wrong that too much torque can also be a problem ?
I've wondered about twisted cable -- it looks more liable to fray and escape contact.

It's possible but difficult... you should know that you're over-torquing because the screw will start to strip.

A high amperage conductor that goes copper-->Aluminum or vice versa usually performs poorly long term, I had to resort to a Cu/Al piece where the two were explosively welded together for a recent job, that stuff isn't cheap.

That's probably how your house is connected to the grid... that's how mine is. Copper wire from the distribution panel is mated to Aluminum wire at the service entrance. Most connections are high amperage and work fine for decades...

Probably the most common mating of Aluminum and Copper wiring... just has to be done correctly...

 

[tga]

You are, of course, correct. I had my electrician install this over 3 years ago and never verified the work. I have just downloaded the v1 manual and it does specify 3AWG copper. Grrr. I'll have to pull new wire before installing a replacement.

If the Al wire is sized correctly, you could install a 100A shut-off switch (Cu/Al rated) near the HPWC and run 3ga Cu from the switch to the HPWC.

I think AL wire has been illegal in NYC for over 30... maybe 40 years... scary stuff

Unless there's some some oddball NYC codes, you're probably thinking of 15A branch circuits. Al is definitely a no-no there, but it's used all the time on large, high power feeders (into the main lugs of your panel, sub panel feeds, etc). That's perfectly safe when installed correctly. Also, newer alloys were introduced in the 70's that are safer (less brittle and less thermal expansion).

The problem with 15A branch circuits back in the late 60's/early 70's was essentially newer Al Romex used with Cu-only switches/outlets and wiring styles.

Aluminum Wiring

 

[Lloyd]

You can use Aluminum Wire... as specified on page 10.

I ran 2-2-2 triplex to my HPWC. 2-2-2 was ~$0.70/ft vs #3 copper is ~$4/ft for 4-strand. For a 70' run I saved ~$200. Everything is outdoors so I'm not worried about a fire I wouldn't run Aluminum wire through walls...

I think I will inspect my HPWC... it's been out there for >3 years now no issues.

From your reference

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.

 

[ohmman]

A few answers.

First, the electrician is Tesla certified. He still shows up first in the list when I search on the Tesla website.

Second, he is coming out to replace the wiring with copper at no cost to me. He is unsure why he installed aluminum. I don't love that answer, but it will provide me with the appropriate resolution.

Finally, Tesla has replaced my HPWC. Everything should be installed and operational again on Friday. I plan to verify the install this time around.

Thanks for all the responses and concern.

 

[boaterva]

A few answers.

First, the electrician is Tesla certified. He still shows up first in the list when I search on the Tesla website.

Second, he is coming out to replace the wiring with copper at no cost to me. He is unsure why he installed aluminum. I don't love that answer, but it will provide me with the appropriate resolution.

Finally, Tesla has replaced my HPWC. Everything should be installed and operational again on Friday. I plan to verify the install this time around.

Thanks for all the responses and concern.

Well, I sure didn't expect that first answer! I wonder what Tesla does with the installation photos they get from their 'certified' people, or that may be a more recent requirement? I would think AL wiring would be something visible; mine sent quite close shots of the wiring.

At least you got a new version you can load-balance if you ever need to out of all this!

 

[nwdiver]

Second, he is coming out to replace the wiring with copper at no cost to me. He is unsure why he installed aluminum. I don't love that answer, but it will provide me with the appropriate resolution.

How far is your distribution panel from the HPWC?

 

[ohmman]

How far is your distribution panel from the HPWC?

25' linearly, about 45' of cable run.

 

[nwdiver]

25' linearly, about 45' of cable run.

Hmmm... that's right about where I would start thinking about aluminum over copper...

There were two reasons I chose Aluminum... one was the cost... it's ~70% cheaper for the same rating. The other is sustainability. 70' of #3 copper wire is A LOT of copper. Our supply of copper is somewhat limited. Our supply of Aluminum is effectively infinite. Using aluminum for anything less than #4 is a terrible idea and is illegal in most areas... but larger gauges are fine.

It looks like your wire gauge is also too small... is that #4? It should be #2....

Your incident did motivate me to inspect my HPWC... so far so good... 10 minutes of charging at 80A...

From your reference

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.

The wire gauge chart specifies Al-Cu. I totally agree that #3 copper is superior... but #2 Aluminum is fine.

 

[habanero69]

Hmmm... that's right about where I would start thinking about aluminum over copper...

There were two reasons I chose Aluminum... one was the cost... it's ~70% cheaper for the same rating. The other is sustainability. 70' of #3 copper wire is A LOT of copper. Our supply of copper is somewhat limited. Our supply of Aluminum is effectively infinite. Using aluminum for anything less than #4 is a terrible idea and is illegal in most areas... but larger gauges are fine.

It looks like your wire gauge is also too small... is that #4? It should be #2....

Your incident did motivate me to inspect my HPWC... so far so good... 10 minutes of charging at 80A...

View attachment 228252




The wire gauge charge specifies Al-Cu. I totally agree that #3 copper is superior... but #2 Aluminum is fine.

Nice camera.

 

[CmdrThor]

I believe his error is worse than that: Copper is mandatory, ferrules are highly recommended. If you ask me, I say: ferrules are mandatory. It's Russian Roulette in there, with such a small space, such huge wires ... good contact has a much higher chance with the screw pressuring a solid metal cap.

great point I am going to add ferrules to my installation this weekend

Regarding ferrules if you have the new V2 Wall Connector and you use the top entry bracket you don't need ferrules. You connect your supply wire to the lugs in the top entry bracket and it has preconnected wires with ferrules that go from the bracket into the Wall Connector. Those preconnected wired are more flexible as well and much easier to work with.

 

[Zero CO2]

If the Al wire is sized correctly, you could install a 100A shut-off switch (Cu/Al rated) near the HPWC and run 3ga Cu from the switch to the HPWC.


Unless there's some some oddball NYC codes, you're probably thinking of 15A branch circuits. Al is definitely a no-no there, but it's used all the time on large, high power feeders (into the main lugs of your panel, sub panel feeds, etc). That's perfectly safe when installed correctly. Also, newer alloys were introduced in the 70's that are safer (less brittle and less thermal expansion).

The problem with 15A branch circuits back in the late 60's/early 70's was essentially newer Al Romex used with Cu-only switches/outlets and wiring styles.

Aluminum Wiring

you are correct I was thinking about hose wiring 15 AMP breakers ...

 

[redi]

I have a 100A circuit and a short copper run. After replacing the breaker once and the HPWC cable once (too hot for longevity), I've gone to 52A and have not had to replace anything else for a several years.

If your mission allows it, a lower (but still fast) rate might put less stress on your set-up and still give you what you want and everything will last longer.

 

[tga]

you are correct I was thinking about hose wiring 15 AMP breakers ...

I don't have my NEC copy handy, but I'm pretty sure it disallows solid Al, specifically for 15A branch circuits. Heavier gauge wire is all stranded. My 1972 house is all copper, except for 6ga Al feeding the range. When the kitchen remodel happens, we'll relocate the stove and rewire with Cu (unless we go to gas).

I have a 100A circuit and a short copper run. After replacing the breaker once and the HPWC cable once (too hot for longevity), I've gone to 52A and have not had to replace anything else for a several years.

If your mission allows it, a lower (but still fast) rate might put less stress on your set-up and still give you what you want and everything will last longer.

Since P = I^2 * R, others have pointed out you can cut heating in half by reducing the current by sqrt(2). So 56A is half the heat of 80A, and still exercises/tests both chargers (in my older dual charger car).