In the process to perform a DIY 400A main panel upgrade,

I have spliced these wires coming from the new main panel to a cable that goes to a sub-panel. This is a pre-existing box where the same cable was spliced to a different one going to my old main panel. The old cable has been removed.

Splice box

I used "polaris" connectors that were very expensive - more than 100 dollars for the three pictured above. Here a detail view:

Polaris ITG3/0

  1. Are these connectors rated for 1/0 aluminum wire? There is NO gel inside the holes nor any marking that suggests it
  2. I looked online and it was surprisingly difficult to find a torque for these. Best I found is 250in*lbs that sounds pretty high for a 3/16 hex driver
  3. Is it OK to ground the box with that copper wire?
  • Ilsco PBTS is comparable to the Polaris ITG, but often priced 40% lower and also dual AL/CU rated (at least the one I checked was). And 250 in-lbs isn't so much - maybe you're thinking of ft-lbs? 250 in-lbs = 21 ft-lbs. You can see why connectors tightened to "that feels good" are often under-torqued.
    – Greg Hill
    Commented Feb 11 at 19:10
  • A hex key bolt with 3/16 driver is typically a 1/4" threaded bolt size, which (for a grade 5 steel) typically takes 11ftlbs. I am not sure if this threads into steel or aluminum, in any case a torque of over 20ftlbs seems high to me. Maybe this screw is actually bigger than 1/4" but in my main panel, a screw that takes a much bigger 3/8" hex driver has a listed torque of 250in*lbs Commented Feb 12 at 4:34

1 Answer 1


Those are the wrong connectors

Note the "CU9" labeling by itself on the connectors you have -- this means that they are rated for copper and copper only. You need to get connectors rated CU9AL instead, as that means they're rated for both copper and aluminum.

  • Oh man this is not the first time the local big electrical distributor gives me something that should work but it's not right, and then they charge 30% restock fee. I remember asking about polaris connectors able to splice 1/0 and 2/0 wire but I may not have specified aluminum, because who uses such big copper wires? :( :( :( Commented Feb 11 at 8:59
  • Is it OK to use that ground connection for the box? Commented Feb 11 at 9:00
  • @AlessioSangalli as to the ground wire, what size is that jumper down to the box? Commented Feb 11 at 14:09
  • I recycled a piece of 12ga wire pulled out of a scrap romex Commented Feb 12 at 0:50
  • @AlessioSangalli -- yeah, that's far too small for bonding a box like that Commented Feb 12 at 3:15

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