NEC 250.102

[sosa411]

Would like to have clarification on NEC 250.102(A) Material. Bonding jumpers shall be copper or other corrosion-resistant material. A bonding jumper shall be a wire, bus, screw, or similar suitable conductor.

what type of metal is consider "other corrosion-resistant material"

 

[Smart $]

Would like to have clarification on NEC 250.102(A) Material. Bonding jumpers shall be copper or other corrosion-resistant material. A bonding jumper shall be a wire, bus, screw, or similar suitable conductor.

what type of metal is consider "other corrosion-resistant material"

Stainless steel and bronze for starters.

 

[MasterTheNEC]

Aluminum.....

Just for reference...and yes....Aluminum is very corrosive resistant...

250.62 Grounding Electrode Conductor Material. The
grounding electrode conductor shall be of copper, aluminum,
copper-clad aluminum, or the items as permitted in 250.68(C).
The material selected shall be resistant to any corrosive condition
existing at the installation or shall be protected against
corrosion. Conductors of the wire type shall be solid or stranded,
insulated, covered, or bare.

 

[GoldDigger]

Aluminum.....

Depends on the chemical source of the corrosion. Some things, like some salts, will attack aluminum quite vigorously.

Most inorganic salts are not markedly corrosive for aluminium. Heavy metal salts form an exception here. These can give rise to serious galvanic corrosion due to the reduction of heavy metals (e.g. copper and mercury) on aluminium surfaces.

Alkaline materials, like uncured concrete are another problem.

Galvanic corrosion is an issue with contact to some other metals, like copper.

True, aluminum is generally up there with or superior to stainless for most purposes except galvanic corrosion. That characteristic depends on what other metals the aluminum will be in contact with while wet.

 

[MasterTheNEC]

Depends on the chemical source of the corrosion. Some things, like salt, will attack aluminum quite vigorously.

Supply source please...but that can be true to ANY of the conductive mediums mentioned.

AA6000 is used extensively in Marine applications and lug applications. But that feels like a trick question on my part. Removing any possible termination issue...(as with any conductor CU or AL) once the oxidation forms on the AL wire it is actually more protective than the oxidation on CU in terms of breakdown.

You might find this document helpful in understanding AL and why they are very corrosion resistant.
http://www.isotecsecurity.com/isowp/wp-content/uploads/2016/03/aluminum_corrosion.pdf

Here is an except from that document :

"Aluminum is actually a very active metal, meaning that its nature is to oxidize very quickly. While a weakness for most metals, this quality is actually the key to its ability to resist corrosion. When oxygen is present (in the air, soil, or water),aluminum instantly reacts to form aluminum oxide. This aluminum oxide layer is chemically bound to the surface, and it seals the core aluminum from any further reaction. This is quite different from oxidation (corrosion) in steel, where rust puffs up and flakes off, constantly exposing new metal to corrosion. Aluminum’s oxide film is tenacious, hard, and instantly self-renewing."

 

[MasterTheNEC]

Just for additional clarification...here is the 2017 NEC Language on Bonding Jumpers.


(A) Material. Bonding jumpers shall be of copper, aluminum,
copper-clad aluminum, or other corrosion-resistant material. A
bonding jumper shall be a wire, bus, screw, or similar suitable
conductor.