Discussion in 'General Technical Questions and Answers' started by N0RDE, Jun 27, 2021.
Copper prices are through the roof! Could aluminum rods and wire be used instead?
73 de N0RDE Jon
Table 250.66 in the NEC shows sizes for Grounding Electrode Conductors, based on largest ungrounded conductor size in the AC service.
These might be useful for determining how much larger the Al has to be than Cu -
For example, if you are looking for an aluminum alternative to copper and the spec you have shows 6 ga copper, use 4 gauge aluminum.
Depending on the environment, copper can withstand weather a lot better than aluminum. This might not be the time to save a few nickles.
Yep. Found this -
*Bare aluminum or copper-clad aluminum grounding conductors
shall not be used where in direct contact with masonry
or the earth or where subject to corrosive conditions.
Where used outside, aluminum or copper-clad aluminum
grounding conductors shall not be terminated within 450 mm
(18 in.) of the earth.
As to ground rods, I can't believe they are going to work if they are aluminum, if you intend to drive them. It took a stepladder and a RotoHammer attachment to drive 8 ft copper rods. It wasn't an easy "push".
For available ground rod materials, I found Copper-Bonded Steel (not Copper-Clad, no longer approved), Stainless Steel, Solid Copper and Galvanized Steel. Aluminum is not listed, probably because it has no corrosion resistance as a grounding electrode as well as being impossible to drive.
"Copper" ground rods normally aren't really copper: They're usually copperclad steel with pretty thick copper cladding, but the main rod that takes the beating when you hammer it in is steel.
Aluminum underground doesn't last long before it disintegrates. Even aluminum towers come with steel bases so the aluminum uprights never touch the ground or the cement pad.
Aluminum turns into fine powder over time.
About 3 years ago, I smelled a smell like hot electronics around my breaker panel. Had some breakers arcing. Called electrician. The aluminum backboard in the breaker panel had started to corrode and fine powder everywhere - high resistance to ground causing arc. Pulled all breakers and replaced backboard with a copper backboard. Problem solved.
This was in a dry area and took 20+ years to develop; put aluminum outside and it will start going to powder quick.
Don't use aluminum in your ground system.
And in the late 70s they used "Underground" mains wires buried here , Aluminum... if even a grub or mole eat the insulation on them they turn to powder and you lose a Leg from your Grid and the "company" charges you $1600 to put a "patch" in place to restore power.. SUX
Stuff I didn't know in my 20s still causes me issues now... Overhead wires would be better long term...
You seem to have been fortunate regarding price. Many private contractors are getting 15 bucks a foot for that typical 75 foot long trench at 18 to 24 inches deep. That does not count the typical 2 conductors and return, nor the schedule 80 PVC conduit for 18 inches deep. The guy digging the trench ( yes, I have done some ) remembers that he cut some tree roots and a few other things where only hand-digging would work. This usually amounts to 8 to 10 feet at either end of the trench. With trees, this can amount to 6 billable hours per day for a journeyman and apprentice multiplied by two days. Special P.P.E. is wise for meter removal / installation in certain cases. Penetration of concrete slabs can add to the job, because folks sometimes fail to respect the 'call before you dig' and easements with storage sheds, etc.
That is not what the Electric did here... They used "Finder" after they put a "Sounder" on the local 6 house feed panel for the underground. They dug a hole with a foot shovel, found the cable with the break and I saw the other one that did not have a break. They put a "PATCH" that I probably do not trust after they striped both sides of Left side feader, Right side a still working. So this crappy AL feeder wire is patched not fixed. I looked into what it would cost to replace my left and right feeders underground and it is "OUT OF SIGHT"
Our 70s underground conductors are not in any conduit plastic or otherwise
I am not sure about Ohio, but in Texas the depth must be 24 inches for cable not in conduit- and the cable must also be rated for direct burial. In addition, there must be a schedule 80 PVC or better conduit from the trench to the meter for new construction. Unfortunately, almost all 'repairs' do not call for upgrades to the adopted version of the N.F.P.A. N.E.C. ( National Fire Prevention Association National Electrical Code ) that was approved by version ( year ) for your state or municipality. Prices on copper have resulted in many commercial thefts in recent years. 'Tin-plated' copper is being used more frequently because it can be mistaken for aluminum by some folks. You may want to consider a back-up system for those appliances you can not do without, such as the range-fridge-furnace fan-water heater (if electric, yet gas requires a pilot with electric shutdown)- and your communications systems. If you have not seen any 'rolling blackouts' in Ohio yet, that may be because Canada is selling electric power to the U.S. The systems built for Detroit no longer see the loads once present, yet population continues to increase.
A foot shovel goes to 2 feet easy for the CREWto fix it.. No conduit per code in 1977 when this was built, I have had black out protection for decades, we get ice storms that take out the over head pole HV feeders farther down the roads that then take out the stuff they put underground years later...
tin plated copper is far more ductile than aluminum at the rated amperage, plus the tinned coating is more resistant to corrosion.
the downside of it is slightly higher resistance per 1000 foot.
but this is a negligible issue for most home installations.
even here in pa direct burial cable needs to be in conduit.