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Discussion in 'North America' started by BobtheV, Dec 24, 2013.
What is the largest gauge wire that can be hooked up to a HPWC?
The largest ground wire that you can use is #4, but code only requires #8 for a 100 Amp circuit. All of this is for copper.
If you are going to use a 100 Amp breaker, then for residential, you are required to use at least #3 AWG wires for the power connections. For a business install, code requires #2 AWG wire. I don't know the maximum size that you can use, but I did an install with #2 at my house. The electrician had to wrestle with the big wires in the HPWC, but ended up with a clean install. I used the #2 to save a little on Voltage drop. That was somewhat extravagant, I'm not sure why you would go any bigger on the wire.
Update: Just opened the HPWC up and looked inside. The connector for the power wires into the HPWC is rated for #2 to #14 AWG wire. #2 is as big as you can go.
Pretty much what Cottonwood says.
The installation manual specifies certain gauges of wire as well. While helping my installer/electrician, I recall that he'd noted the heaviness of the wire versus the slots the HPWC allowed. It was a tight fit.
#2 is the maximum for the lugs in the HPWC. It barely fits. #3 fits more easily, and is a little more flexible, but is harder to find and more expensive than #2 generally.
If you've got some fatties delivering the goods you can always pigtail down to a gauge that will fit the HPWC. Use a separate box (with cover plate) if necessary. But this implies that you did the same on the input end as well (if it didn't fit in the breaker).
The HPWC manual says for 100A to use a maximum of 3 gauge which can be hard to find. My electrician used 2 gauge though it was a tight fit. I'm amazed at how small the HPWC is. It's a fraction the size of the shut-off panel next to it required by my city.
I just finished installing an HPWC in my second home. It was pretty easy because I put a 200 Amp sub-panel in the garage when I installed the HPC for the Roadster years ago. That panel is surface mount, and I don't mind surface mount conduit in my garage so most of the install was very simple and straight forward.. A pair of #2's and a #8 for ground feed just fine through the 1" conduit that Tesla recommends. Because the HPWC is MUCH tighter than the breaker panel, I started making connections there and then finished the connections in the 100 Amp breaker inside the Siemens CB Panel.
I completely agree with Lloyd's comment, "#2 is the maximum for the lugs in the HPWC. It barely fits." In fact, here is my analogy. Connecting the #2 wires in the HPWC is like wrestling an anaconda in your front coat closet, while connecting the same wire in the Siemens breaker panel, is like guiding a large, gentle horse into its stall.
I know that Tesla prides itself on sleek, industrial design, but they went too far in the HPWC. A little more space, and cable lugs one size larger, would have saved a lot of installer headaches across North America...