Dissimilar Metals
- Thread starter T's C6
- Start date
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- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
In a word, yes!
Look to use insulating plastic bushings or similar measures to keep the two metals from direct contact.
What could or would happen to the ground wire?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The copper will be corroded away and will eventually fail. Until then it will work just fine.
- Location
- Massachusetts
Bare copper conductors are installed inside steel raceways everyday.
I am not so sure it is an issue to worry about.
I am not so sure it is an issue to worry about.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Contact over a very wide area (as inside a steel raceway) is not going to pose the same level of corrosion problem as a few small point contacts.
Current density determines the degree to which a particular small part of the wire will be corroded.
Also, FWIW, inside a steel raceway will not be as bad as with direct salt spray exposure.
The true test will be in watching the support area over the first year. Then it will be time to make a decision on whether to do anything. A thick enough wire will last a lot longer.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Where can we find a formula/table for calculating this corrosion factor?Contact over a very wide area (as inside a steel raceway) is not going to pose the same level of corrosion problem as a few small point contacts.
Current density determines the degree to which a particular small part of the wire will be corroded.
Also, FWIW, inside a steel raceway will not be as bad as with direct salt spray exposure.
The true test will be in watching the support area over the first year. Then it will be time to make a decision on whether to do anything. A thick enough wire will last a lot longer.
Do we have to tag it with an expiration date at which time it should have corroded enough that it soon needs replaced
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Forgot to mention that solid will last a lot longer than stranded.
Although 4/0 solid would be a lot more like a rod electrode than a GEC.
Although 4/0 solid would be a lot more like a rod electrode than a GEC.
- Occupation
- Licensed Electrician
Which opens the door to another question........What is it that is so great about copper ground rods?
- Location
- Massachusetts
I don't see were the OP said it was subject to direct salt spray.
Not much. In fact, they can cause failure of nearby steel structures by corroding them, if soil resistivity is good.
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
http://www.hydra-zorb.com/
use these to strap the 4/0 to the strut..
if it's current carrying conductors, use a non ferrous strut to prevent induction heating
of the conductor. i've used them in a number of places.
- Location
- Illinois
- Occupation
- retired electrician
Those clamps are zinc coated. With a copper/zinc cell the zinc is the anode and will be the part that is corroded away.
five.five-six
Senior Member
- Location
- california
slightly off topic but I am on a job currently and the project manager has stainless steel air lines he is going to put on my rack, I advised him that he should look into the insulating strut straps because of the dissimilar metals. I was kinda talking out my rump becaus i really don't know if it's the galvanized unistrut or the stainless steel tubing that will give way first.
- Occupation
- Licensed Electrician
Nothing will happen in terms of dissimilar metals. Stainless steel doesn't react with anything.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
FIFY
That lack of reactivity is one reason that stainless fittings (bolts, screws, washers) are used to connect dissimilar metals (e.g. aluminum vs steel).
The other reason is that its electronegativity is roughly halfway between that of the two metals mentioned above.
- Occupation
- Licensed Electrician
I think you used that word on me once before. I had to look it up again.
mgookin
Senior Member
- Location
- Fort Myers, FL
- Occupation
- Retired inspector, plans examiner & building official
For Chem101 just remember it's from bottom left to upper right on the periodic table.
But let me ask you, when a test question says to identify the element with "greater electronegativity" what are they asking for? (imagine a number line)
rt66electric
Senior Member
- Location
- Oklahoma
#4 bare or 4/0 ?? solid or stranded??
#4 bare or 4/0 ?? solid or stranded??
did you mean #4 bare or 4/0 ?? solid or stranded?? 4/0 solid would be kinda hard to manage......
#4 bare or 4/0 ?? solid or stranded??
did you mean #4 bare or 4/0 ?? solid or stranded?? 4/0 solid would be kinda hard to manage......
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