POLARIS CORROSION

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
Ah, that's not simply over-torqued and I wouldn't call it such; that's flat out strand damage. For a spec of 400 inch-pounds (33.3 ft-pounds), cranking to 500 is 25% over but probably isn't going to break any strands. OTOH double-torque might well damage the strands.

Or, there's over-torque and there's gorilla-arm massive over-torque damage.
Most damage I've witnessed is in mostly residential panels. Specs usually 250in lbs on mains, that is not much at all, seen guys not using a torque wrench thinking that you wrench tighten. Most times if torque it out, ends up in neighborhood of 60 ft lbs. 3X the recommended torque. No gorilla needed to do that.
 

Sea Nile

Senior Member
Location
Near the Masters Golf tournament
Occupation
Apprentice - Retired Army 35T
I have limited experience with Polaris connectors, but I have used them a few times to connect an attic furnace.
The Polaris connectors I was given only accepted a small hex wrench.

I could not imagine being able to over torque that connector to the point of damaging the conductor with that small of a hex wrench. I think the socket would round out before the conductor got damaged.

What size tool did these connectors require?
 
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jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Most damage I've witnessed is in mostly residential panels. Specs usually 250in lbs on mains, that is not much at all, seen guys not using a torque wrench thinking that you wrench tighten. Most times if torque it out, ends up in neighborhood of 60 ft lbs. 3X the recommended torque. No gorilla needed to do that.
That's interesting. Most times I check torque on those kinds of connections I find them loose. And I have a habit of torquing 250in-lb. connections to a bit less than spec because too often something breaks if I torque it to spec.
 
One thing that overtorqueing can do, especially if the wire is near or below the range of gauges the lug is made for, is to spread out the strands so that some of them do not participate in the connection. Resistance, heat... off to the races.
Maybe. I am skeptical how much scientific analysis goes into torque values. I think it's more just based on the size of the set screw in the lug. Considering the typical wide range of conductor sizes, different conductor materials, and stranding types that can go in a typical lug, I am skeptical the published torque values are meaningfull.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Maybe. I am skeptical how much scientific analysis goes into torque values. I think it's more just based on the size of the set screw in the lug. Considering the typical wide range of conductor sizes, different conductor materials, and stranding types that can go in a typical lug, I am skeptical the published torque values are meaningfull.
Yeah, it would stand to reason that the published value is assumed to fall within the overlapping ranges of acceptability for all those different factors you mention. Which means for any given conductor choice, the risk of overtorquing vs. undertorquing could be different.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
I have limited experience with Polaris connectors, but I have used them a few times to connect an attic furnace.
The Polaris connectors I was given only accepted a small hex wrench.

I could not imagine being able to over torque that connector to the point of damaging the conductor with that small of a hex wrench. I think the socket would round out before the conductor got damaged.

What size tool did these connectors require?
FWIW there are many sizes of Polaris blocks; some of them can take 500KCMIL conductors.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Yeah, it would stand to reason that the published value is assumed to fall within the overlapping ranges of acceptability for all those different factors you mention. Which means for any given conductor choice, the risk of overtorquing vs. undertorquing could be different.
I don't think anyone has said that the levels of risk are the same.
 

Zee

Senior Member
Location
CA
Aluminum J box under panels on hilltop roof location (standing sema metal)

Large 1" KO hole left open on bottom side of J box .....most that would allow would be moist air.

Correct size Polaris for the #10 THHN and PV wire used.

Wire torque who knows?

Polaris was pointing uphill. (wires and polaris opening pointing down hill)

Will post pic ......but this site won't let me :unsure:
 

Zee

Senior Member
Location
CA
Solaredge DC system.

Maybe it was just sloppy wiring, poor wire stripping, or not pushing in wire enough, or over/under torquing.

Thank you for the valuable thoughts.
 

Phil Timmons

Member
Location
DFW
Occupation
Depends on the pay and the day
Have seen something like this from local chemicals in the air.

For Copper Corrosion, look for Chlorine. Pool chemicals, Industry, Water or Sewer plants.
 
Location
22802
Occupation
Electrician
Solaredge DC system.

Maybe it was just sloppy wiring, poor wire stripping, or not pushing in wire enough, or over/under torquing.

Thank you for the valuable thoughts.
I was just thinking about this, reading through. If you damaged the strands during initial stripping, and then over-torqued the block, I imagine you could sever strands pretty easily, leading to increased resistance, heat, etc. We've seen a number of these melt; polaris, burndy, panduit, doesn't matter. I have searched the internet for hours trying to find recalls, examples of bad batches, etc. I'm convinced it's installation error 100% of the time. Having a properly calibrated torque screwdriver/wrench is critical.

@electrofelon The Panduit PCSB4 has a torque spec of 50 in-lbs for #4-#8, and 45 in-lbs for #10-#14. I see this on a lot of panelboards we install as well. Different torques for the same size lug depending on wire size.
 
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