Zinc powder is in your gold bond and other foot powders. How many times have your feet caught on fire? Did your gold bond powder come with a MDS? These sheets are LIABILITY controls, and have little basis for your conumdrum of junk.
Guess we hit a nerve in you here. JUNK? You tell us you are a teacher and then you call anti-oxidants junk?
You are flat out wrong about dissasembling a cable and sanding each strand, in fact, its just inflammatory and silly. The specs that I see are for the outer surface of the cable - aluminum- to be sanded or abraded and then the material [not axle grease, hair pomade, shampoo, moly grease, cutting oil or used motor oil] - a dedicated, electrical grease or anti-oxidant - be throughly incorporated into the outer strands, added to the terminal, and for me, carefully coated around the exterior of the assembly to exclude oxygen and add decades to the inevitable degredation of the terminal.
I am getting confused here. I have seen rigid metal conduit that was threaded using cutting oil that rusted after a year or two. Is that lubricant no good for oxidation?
Yes, you are very confused. Let me help you out. Thread cutting oil is fish based, and is, well, CUTTING oil. It is not labeled or intended to be a anti-oxidant, but a anti wear and chatter lube for the process of milling a thread on a pipe whose rusted threads bear no importance to electrical continuity. Its purpose is to reduce wear on threading dies.
I can’t help but wonder why the power companies throughout America don’t use antioxidants when they terminate in meter bases if this junk is supposed to be so good.
I did 4 major line extensions last year. One was underground, and the POCO used aluminum cable and the installer very much used an anti oxidant on his terminal connections. The others were overhead, outdoor pole drops, and I did the wiring to the meter socket. The inspector would not pass them without liberal coating of anti-ox on the aluminum drop wire from the weather head. If it was copper to copper, it was not required, but I would have used it also. An ounce of prevention is worth a pound of cure.
You are correct about torque. A hydraulically crimped and shrink covered splice - such as on the weather head- will suffice. Meter sockets have matching metallic properties, and have very large connection forces, and perhaps may not thus require a lubricant or antioxidant [electrically speaking, most incorporate both qualities]
But frankly, I have not observed the meter being inserted, and perhaps an electrically rated grease is being used by the smart utilities.
What usually happens is the junk is squirted into the terminal and then the conductor installed which does nothing to protect the conductor
What this means is that electrical teachers are not doing their job in educating budding electricians. And electrician are not reading the can. And electricians want to get paid, and know that the homeowner is ignorant of good practice. And they want to get the job done and watch the football game. Kind of like that o-ring on the space shuttle.
The terminal does not need to have this junk applied for any reason.
The TERMINAL is why electricians have buckets of clipped off breakers. They rust. they corrode, the screws cannot be turned. Many are al on al - a guarantee of garbage in 3 years. How do your non anodized aluminum windows look after 5 years?
Finally, about your tourque. Are you aware that a big gorilla can tighten the nut on a 2 or 4/0 AL cable, to where his own nuts hurt, and the next day I can come in and give that same screw another EASY half turn? and a year later, I can give it another 3/4 turn. Metal flows, especially a cluster of soft small wires bound up in a nearly one size fits all terminal. Then it softens with heat from use, and your 'torque' is lost. that leaves space for oxidation, vibration, arcing and failure. The anti oxidant at least may fill the resultant spaces and reduce the chance for the oxidation portion.
I hope your class has a chapter on this reality.
Here is a very expensive test of connections exposed to hydrogen sulfide gas - copper, generally, that does your torque point justice on INTERIOR connections at the microscopic level.
Pay special attention to the conclusions of these tests of moisture exposed connections of all typical materials used in panels: Added resistance of 5 to 15% will rather disturb the original engineering of cable sizes... 10% was considered a failure.
http://www.copper.org/applications/electrical/building/pdf/A6108.pdf
A mechanical or compression high current connection relies
on good asperity contact at the connection interface to maintain
a low contact resistance. Asperity contact is maintained by the
residual contact force on the connector, which is supplied by
the screw fitting in a mechanical connector, or the residual
stress in the deformed metal in a compression connector.
Under corrosive conditions, a poor connection may build up
insulating oxides in the spaces between the asperities and at the
edges of the asperities. High level, short duration current
bursts are applied to the samples for sufficient duration to
produce elevated temperatures at the asperity interface between
the connector and conductor. The intention is to produce
softening or melting of the asperities at the interface during the
test. In a connector which has a build up of oxides, softening
or melting at the asperities may cause loss of asperity contact if
the residual force on the connector is insufficient to re-establish
asperity contact with the oxide layer present. In an oxide free
connection, the residual force can actually improve asperity
contact when the asperities soften, resulting in a lower contact
resistance.
