ECN Forum Forums Code Related Discussion Building Codes for Electricians anti oxidant on aluminum conductors

Section 110.10(B) requires listed or labled equipment to be installed in accordance with any instructions included with the listing.

While only UG or UV conductors need to be listed, most conductors are listed anyway.

When the UL White book is consulted, it turns out: "Conductor Termination Compound — Some connectors are shipped pre-filled with conductor termination compound (antioxidant compound). For non-prefilled connectors, conductor termination compound may be used if recommended by the connector manufacturer as preliminary preparation of the conductor."

The recommendations I have read always prescribe oxide inhibiting compound for damp or wet locations with aluminum wires.

The answer is in the word "may" if it was required the word would be "shall".

In regards to anit oxidant, I "shall" continue to apply it to my aluminum terminations even though there is no real requirement to do so. The reason is it "may" become a damp location due to majority are service drop conductors located inside a 3r meter enclosure and we got humidity and salt mixed in the air we breath here. I find salt built up in some extremely curious places after any big winter surf swell has passed.

... And the lug manufacturer "recommends that you do so but this question was based on what the inspector could make you do using the NEC as a reference.
I agree using the goo is a good idea and if I was inspecting your job I would look favorably on seeing it. I might even ask why you didn't if it wasn't there but I would be on shaky ground tagging it.

I would never use aluminum wiring without gooping it. After experiencing 30 years in the business this is a no brainer.

We replace 3 services a month that used aluminum wiring in a 900 unit apartment complex. All are the result of no anti oxidant. I'm very surprised that some do not think it's necessary.

One of the first journeyman I had the opportunity to work with told me that aluminum was good for two things. Buying and carrying. Since he was a Marine that was in the first invasion wave at Iwo Jima (WWII), I thought I'd listen.

The reason some of us do not see it as necessary is that they have changed the make up of aluminum conductors. Those services you are changing are very likely done with the old alloy and not the new.

Truth be told I do use it for permanent work, I skip it for temps.

I just took a service off a building that was installed in 1972.This building is located about 50 feet from salt water. No goop was used and the Aluminum conductors were as shiny as the day they were installed

At work (PoCo) we don't use anti-oxidant with our connections.
But there is conductive grease inside all of the crimp lugs we use.
Our connection system is in two parts:

• rough up the aluminium strands with a clean wire brush.
• Shove it in the crimp lug and turn it a couple of times, then crimp it.

I've never had an aluminium crimp fail yet and in case you were wondering, the grease does not contain anti-oxidant.

There are several issues to consider when using aluminum for electrical work, most of which have already been addressed by the manufacturers to some degree .

The use of alloys for conductors is strictly limited, because even very low percentages of alloying metals deliberately added [ & not forgetting the inevitable impurities in aluminum originating at the smelter, like silicon and iron ] increase a metal's electrical resistance and susceptibility to corrosion. But aluminum is a very weak metal, difficult to obtain pure because any impurities in the bauxite ore pass into the metal by the only commercial process we have. What is not generally realised is that work-hardened metals have a higher electrical resistance. When drawn through dies, copper wire work hardens so the wire we use is not as electrically conductive as it would be if annealed. Aluminum alloys also age harden naturally [ solid-solution precipitation hardening] which also affects conductivity.


'Anti-oxidant' implies that the join, where the wire changes over to copper wire, requires protection from oxygen. Disimilar metals, in contact and in the presense of an electrolyte can corrode as anode/cathode in an electric cell. The actual electrolyte determines the corrosion- salt water could create chlorides not oxides. You could thus get sulfides, hydroxides, chlorides, carbonates etc. etc.
ALL aluminum surfaces, alloys included, have a thin layer of aluminum oxide on the surface. The metal is extemely reactive, and without this self creating/healing coating would probably burn violently in air!

There are several issues to consider when using aluminum wire for electrical work.

The use of alloys for conductors is strictly limited, because even very low percentages of alloying metals deliberately added [ & not forgetting the inevitable impurities in aluminum originating at the smelter, like silicon and iron ] increase a metal's electrical resistance and susceptibility to corrosion. Aluminum itself is a very weak metal, but difficult to obtain pure because any impurities in the bauxite ore pass into the metal by the only commercial process we have.
What is not generally realised is that work-hardened metals also have a higher electrical resistance than when soft. When drawn through dies, copper wire work-hardens, so the wire we use is not as electrically conductive as it would be if annealed. Aluminum alloys also age-harden naturally, [ solid-solution precipitation hardening ], which also affects the conductivity. This is not easy, is it?

'Anti-oxidant' implies that the join, where the Al. wire changes over to copper wire, requires protection from oxygen. Disimilar metals, in electrical contact and in the presence of an electrolyte can corrode as anode/cathode in an electric-cell. The actual electrolyte determines the corrosion; salt water could create chlorides not oxides. You could thus get sulfides, hydroxides, chlorides, carbonates etc. etc.

ALL aluminum surfaces, alloys included, have a thin layer of aluminum oxide on the surface. The metal is extremely reactive, and without this self creating/healing coating would probably self-ignite and burn violently in air!

So in reality, a freshly made dry, clean join between the two metal conductors, [ using suitable gage wire to suit the properties and usage and using the properly specified connectors and supports] needs to be protected against the contamination and damage by some future arrival of an electrolyte, whether it be damp, salt incursion or otherwise. Vaseline grease would probably be as good as any, provided it were acid neutral, [ ph 7.0 ], just as a physical barrier.

Alan