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You're confusing two people in this thread then. @Benjamin Brooks revived this thread, talking about the builder who ran a 6 gauge aluminum line for car charging, and people were discussing the reasonableness of maybe a 50 or 40 amp circuit for that.
The post you just replied to, though, was @AmpedRealtor who is running a 100A circuit, supplying 80A. Clearly, you couldn't ever use 6 gauge for that, and he never mentioned wire gauge. He was just talking about how aluminum can be used for part of the wiring run.
As an update, 2 electricians told me different stories. One said I could do a 50A circuit and other said 40A max for the existing AL wiring.
It's apparently 90C rated AL wire based on the insulation markings so I think/hope 50A is reasonable... anyway; went ahead & put a NEMA 14-50 on the line and used my old Gen 1 UMC to pull 40A to charge up.
Seems to have been ok. Circuit's IR drop @ 40A wasn't concerning, even after multiple hours of heating from 40A load.
It's apparently 90C rated AL wire based on the insulation markings so I think/hope 50A is reasonable... anyway; went ahead & put a NEMA 14-50 on the line and used my old Gen 1 UMC to pull 40A to charge up.
Seems to have been ok. Circuit's IR drop @ 40A wasn't concerning, even after multiple hours of heating from 40A load.
Huh. This should be a pretty well-defined answer, and I would have not expected two different ones.
Well, sure, a lot of wire is itself rated to 90 C, but there is the issue of the lowest common denominator for the weakest link in the entire chain, and it has to be downgraded to that level. The thing is, residential breakers are basically just not made rated for 90 C usage. They are only up to the 75 degree C rating, and the receptacles are generally too, so that is always going to limit your use in the ampacity table to the 75 C column, even if the wire by itself would be allowed to the 90 C level.
I never did see an answer to this issue from page 1:
Knowing the type of wire and whether it's wires in conduit would be informative.
So I'm still kind of curious on this, because an electrician should be able to point to something to explain his circuit rating rationale, and I would love to hear that from the two guys who gave different answers. But maybe it was just what they were referring to with their wording. Because if one was saying "a 50A circuit" and the other was saying "40A current supply", those are really the same thing, because of the 80% usage for continuous use circuits.
brucet999
Active Member
2/2/2 Aluminum SEU is about $1.40/foot. If your ends are AL compatible then this is better than 6 awg CU. I agree 6 awg AL is not appropriate for 40A continuous load. The issue is how hot will you let the wire get. It probably won’t burn the house down but observe there are higher temperature versions of wire if willing to accept more heat loss for lower cost wire.
The 1st generation HPWC had AL compatible terminals which accepted 2 awg wire. My Signature Wall Connector does not.
Is very difficult to bend 6 awg in box for NEMA 14-50R. I’d hate to try to put any aluminum in that space. The 14-50Rs I have seen were not AL rated.
Large Square D circuit breakers that I have seen have aluminum compatible terminals.
Heck, the 200A service to my home is aluminum. Not retorqued in 33 years.
Suggest everyone consider purchasing a digital utility meter on eBay for $25 and meter box for $35 from Lowe’s, Home Depot, etc. placed next to WC makes a convenient place to transition a short length of copper to the WC. Those whose local code require disconnect at WC can use that to transition.
The meter will absolutely answer any question as to how much your car costs to drive. The dash only meters that which comes from battery, not that from the grid. Am told TeslaFi and possibly others watch charge current and voltage to extrapolate real grid consumption.
The 1st generation HPWC had AL compatible terminals which accepted 2 awg wire. My Signature Wall Connector does not.
Is very difficult to bend 6 awg in box for NEMA 14-50R. I’d hate to try to put any aluminum in that space. The 14-50Rs I have seen were not AL rated.
Large Square D circuit breakers that I have seen have aluminum compatible terminals.
Heck, the 200A service to my home is aluminum. Not retorqued in 33 years.
Suggest everyone consider purchasing a digital utility meter on eBay for $25 and meter box for $35 from Lowe’s, Home Depot, etc. placed next to WC makes a convenient place to transition a short length of copper to the WC. Those whose local code require disconnect at WC can use that to transition.
The meter will absolutely answer any question as to how much your car costs to drive. The dash only meters that which comes from battery, not that from the grid. Am told TeslaFi and possibly others watch charge current and voltage to extrapolate real grid consumption.
Gadget-X
Member
I went copper. Not sure why you would go aluminum. But I live in Florida on the water and had to replace aluminum and my home service box because of corrosion.
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UncleCreepy
Member
In my case it's because of the cost and availability. I have a 60 ft 1/0 AWG aluminum cable that connects the sub panel in the garage to the main panel.
The connection between the sub panel and the HPWC is 4 ft 3 AWG copper.
When I tried to compare prices for CU and AL, a 1 AWG copper cable was simply not available, plus the available 3 AWG was already pretty expensive, so 1 AWG would have been even worse.
The 1/0 AWG aluminum cable however was dirt cheap. Speaking of "dirt" cheap, it didn't even require a conduit, it is rated for direct burial.
Since the AL wire is oversized for my usage it stays pretty cool at all times, even at 80 Amps continuous load.
For cost savings, and it's real and relevant. Now if someone's panel is already in the garage, and it's just going 10 or 15 feet, yeah, there's no point to use aluminum, because you would have to make the extra junctions to switch it back to copper, so you lose the savings you might have had. But some people have really long runs like 80 or 100 feet from a panel at the other end of the house, and it does make sense to do most of the distance with aluminum in that kind of case.
Gadget-X
Member
Different environments. I would never use aluminum again where I live. Ever. Our 200 amp service box caught fire. Electrician showed me that it was the aluminum connections that was the cause. Without power for 3 weeks... It $&^#&ed. Lucky no electric vehicles back then. The underground power service is aluminum which is scary enough...
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beatle
Active Member
Understand you had a disruptive issue, but there's nothing inherently evil about aluminum when spec'd properly for the load and conditions. The aluminum wire providing 200A service to my house for the past 35 years is still a-okay. Many people have had issues with copper connections, though that doesn't mean they are evil either.
My $.02, if I'm doing the work myself, I'll spend a few extra bones for being able to use thinner gauge wire (copper). I worked with 6awg copper for my 14-50 and it was a bear to work with, even in an unfinished basement. My shoulders were not the same for days. I can't imagine pulling 2awg cable, but I'm also no pro.
My $.02, if I'm doing the work myself, I'll spend a few extra bones for being able to use thinner gauge wire (copper). I worked with 6awg copper for my 14-50 and it was a bear to work with, even in an unfinished basement. My shoulders were not the same for days. I can't imagine pulling 2awg cable, but I'm also no pro.
My town failed my #4 Al 14-50 50A outlet by referring to the Chargepoint install requirement for using 90deg CU. But this requirement refers to hardwiring the Chargepoint and not a supply outlet. Correct? Any problem with my configuration?
As to the first part, yeah, the inspector is referring to something that isn't relevant.
But as to the second part, yeah, there really might be a problem. Most 14-50 receptacles are built for copper wire only. If you are using aluminum directly to it, that doesn't meet the specifications and would be a code violation. There are maybe one or two brands that do build receptacles that are made to accept either copper or aluminum wire, but I don't remember which ones those are, and you didn't specify which one you're using.
What is more commonly done with aluminum situations is that people maybe have a really really long wiring run to do to get to a main location, like a 100 foot run to a garage. Aluminum is done from the main to a subpanel in that location, because subpanels are almost all built to take either kind of wire. Then, the shorter runs within the garage can switch to copper for the outlets or appliances or whatever is going to be connected.
Exactly the case with mine - nearly 200ft of aluminium from main panel to garage sub-panel, and maybe two feet of copper from sub-panel to Gen2 charger.
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