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PowerWall installation mess: Need advice on how to get it resolved

wwhitney

Member
Nov 2, 2017
968
1,317
Berkeley, CA
@wwhitney Thanks for patiently listening to me and providing me with a possible solution.
Good luck with Tesla, do let us know the resolution in the end. Your situation raised some questions that were of interest to me, so you got the benefit of my learning (e.g. how to size feeders for multiple motors/HVAC units). Hopefully I was still able to give you correct answers.

About the torquing the lug nut, thanks for pointing that out. I actually tightened it. Did not realize the electrical screws also need to be torqued appropriately.
Just slightly confused by the phrase "lug nut", from the picture the only connection I see that you undid was the feeder neutral to that subpanel, which uses a slotted set screw in the neutral lug. Were there others?

Anyway, FYI, when tightening a slotted set screw like that, it's important to use a slotted driver that fills or very close to fills the slot. If you use one that's too small, it often can't transfer the required torque and you end up damaging the slot in the set screw instead of tightening it.

Cheers, Wayne
 

valleydude

Member
Dec 21, 2019
24
3
California
Good luck with Tesla, do let us know the resolution in the end. Your situation raised some questions that were of interest to me, so you got the benefit of my learning (e.g. how to size feeders for multiple motors/HVAC units). Hopefully I was still able to give you correct answers.
@wwhitney , No luck getting through to Tesla :( . Meanwhile, I went to a friend's place in the neighborhood and checked out his PowerWall and Solar installation. He has a much bigger house than me, which is about 4300 Sq. Ft. I've attached pictures from his installation.

His electrical system also has a split panel, here are some of the details of his system which look very similar to what needs to be done to mine:
- two 200A Circuit breakers in the main panel (I've a 200A and 150A disconnect)
- the distribution section of the main panel has several heavy loads such as AC, SPA, Oven etc.
- Tesla installed a backup load center with a 200A disconnect
- Tesla relocated most of the loads from the main panel to the Tesla installed backup load center panel (200A). This includes one of the ACs !
- Tesla rewired one of the 200 A disconnect from the main panel, that was previously going to a sub-panel in the garage, to the Tesla Gateway.
- Tesla wired the sub-panel in the garage to a 100A breaker in the backup load center

This is a reaffirmation of the design changes you have proposed for my powerwall installation.
I don't why Tesla did not do this in the first place and why they are not willing to make a change now!

Just slightly confused by the phrase "lug nut", from the picture the only connection I see that you undid was the feeder neutral to that subpanel, which uses a slotted set screw in the neutral lug. Were there others?
Sorry for using the wrong terminology. There are 3 screws in all. I opened each of them to look at the cable to see if i can see any markings.
Anyway, FYI, when tightening a slotted set screw like that, it's important to use a slotted driver that fills or very close to fills the slot. If you use one that's too small, it often can't transfer the required torque and you end up damaging the slot in the set screw instead of tightening it.
I've a torque wrench that I use on my cars, but, don't have a torque screw driver.
Any recommendations for an appropriate torque screwdriver to be used with electrical wiring?
Cheers, Wayne

thanks
 

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wwhitney

Member
Nov 2, 2017
968
1,317
Berkeley, CA
I've a torque wrench that I use on my cars, but, don't have a torque screw driver.
Any recommendations for an appropriate torque screwdriver to be used with electrical wiring?
Well, you need to check the torque specification for the 3 lugs (it might be different for the ungrounded lugs than for the grounded (neutral) but I doubt it). Actually, the torque specification may depend on the wire size, so you may need a calipers for determining the wire size. But more likely #4 to #1 will be the same torque, so you won't have to distinguish.

So if the torque rating is, say, 60 lb-in, and your torque wrench will go reliably go as low as 5 lb-ft, then you can just put a 1/4" hex socket on your torque wrench, stick in the correct 1/4" hex driver bit, and torque it. Don't use much of the handle of the wrench (hold it near the head) and stop if you suspect at all that your torque wrench isn't really calibrated at the low lb-ft you need.

Otherwise, get yourself a torque screwdriver, probably one with a 10-50 lb-in range would be best (assuming the lug doesn't call for more than 50 lb-in). Wiha is a good brand; I have one that looks like the Neiko currently available on Amazon, which is a bit less expensive.

Cheers, Wayne
 

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