Aluminium wire for ground

Thread Starter

meowsoft

Joined Feb 27, 2021
471
What's advantage and disadvantage from use aliminium wire for ground wire ?
50mm² bare copper, 160a capacity is same price with 300mm² XLPE insulated copper wire with 670a capacity
It is good for use aluminium ground wire ?, in datacenter project ?, because we need all surge to be absorbed quickly and adequately and for corrosion problem my solusion is use 50mm² bare copper and 300mm² XLPE insulated aluminium wire (or even use 400mm² aluminium with 810a capacity) together in parallel, is there any problem with that ?, any idea ?
If aluminium is have corrosion problem, they backed up with copper wire, also 670a + 160a is about 830a
 

sagor

Joined Mar 10, 2019
479
Remember that aluminum must not come in direct contact with any copper without some anti-oxidant/anti-corrosion material in the joints.
Aluminum has a higher resistance than copper, so it is not as good a conductor. For any "surge", aluminum will likely have a higher residual voltage. Also, it has a much lower melting point, so any overheating of the wire may cause problems.
Bottom line, unless properly done, do not mix aluminum with copper at the same junctions.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
Remember that aluminum must not come in direct contact with any copper without some anti-oxidant/anti-corrosion material in the joints
Aluminum has a higher resistance than copper, so it is not as good a conductor. For any "surge", aluminum will likely have a higher residual voltage. Also, it has a much lower melting point, so any overheating of the wire may cause problems.
Bottom line, unless properly done, do not mix aluminum with copper at the same junctions.
Yes... of course we use anti corossion joints and bimetal joints, but for that project perspective all things is 24/7 and any surge needs to be absorbs as fast as possible, even 1 minute downtime in one year is so bad

We need absorbs all surges ASAP but with very reliable, also data center is Tier 3.5 between Tier 3 and Tier 4, Tier 4 is exactly same with google's server
 

DickCappels

Joined Aug 21, 2008
7,746
Aluminum wiring is often a pain in the rear. I had a house that was wired with aluminum. When I notice that I felt that I should have sold the house immediately. Had problems with circuit breakers tripping because of the thermal effects of the aluminum-copper interface. Truly a pain.

Here (where I don't speak the language) our underground mains drop failed one night. Some guys from the power company came out and replaced the copper drop with aluminum. My lights have blinked deeply every time an air conditioner came on. When I called my electrician to come check out what the electric company did, the first thing he said when he saw me was "What are you doing with that cr@ppy aluminum wire?"
 

nsaspook

Joined Aug 27, 2009
8,688
Aluminum wiring is often a pain in the rear. I had a house that was wired with aluminum. When I notice that I felt that I should have sold the house immediately. Had problems with circuit breakers tripping because of the thermal effects of the aluminum-copper interface. Truly a pain.

Here (where I don't speak the language) our underground mains drop failed one night. Some guys from the power company came out and replaced the copper drop with aluminum. My lights have blinked deeply every time an air conditioner came on. When I called my electrician to come check out what the electric company did, the first thing he said when he saw me was "What are you doing with that cr@ppy aluminum wire?"
My mom's house was built during the short and dangerous house aluminum wiring period in the 60's-70's. Nearly every electrical socket was burning from Al wiring problems. The insurance company paid for a entire house rewire to copper because that was a lot cheaper than paying for a burned down house. Done correctly with the correct wire, materials and parts it's fine but I won't ever use the stuff on a professional job or in my house.

https://www.startribune.com/hazards-with-aluminum-wiring/509576432/#:~:text=Between 1965 and 1972, over,of aluminum wiring causing fires.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
Aluminum wiring is often a pain in the rear. I had a house that was wired with aluminum. When I notice that I felt that I should have sold the house immediately. Had problems with circuit breakers tripping because of the thermal effects of the aluminum-copper interface. Truly a pain.

Here (where I don't speak the language) our underground mains drop failed one night. Some guys from the power company came out and replaced the copper drop with aluminum. My lights have blinked deeply every time an air conditioner came on. When I called my electrician to come check out what the electric company did, the first thing he said when he saw me was "What are you doing with that cr@ppy aluminum wire?"
Thanks... nice abswer, I think use larger copper wire is good idea, than paralleling with aluminium wire, maybe 120mm² bare copper wire
 

BobaMosfet

Joined Jul 1, 2009
1,854
What's advantage and disadvantage from use aliminium wire for ground wire ?
50mm² bare copper, 160a capacity is same price with 300mm² XLPE insulated copper wire with 670a capacity
It is good for use aluminium ground wire ?, in datacenter project ?, because we need all surge to be absorbed quickly and adequately and for corrosion problem my solusion is use 50mm² bare copper and 300mm² XLPE insulated aluminium wire (or even use 400mm² aluminium with 810a capacity) together in parallel, is there any problem with that ?, any idea ?
If aluminium is have corrosion problem, they backed up with copper wire, also 670a + 160a is about 830a
From a conductive standpoint, the specific resistivity of each is (@20C):

Copper: 10.37 Ohm's per cmil/ft
Aluminum: 17.02 Ohms per cmil/ft

A cmil is 1/1000th of an inch.

A 3AWG copper wire will handle up to 313A* if ambient is 0C. Aluminum of the same AWG will only handle 248A*.

You would need 2/0 AWG Copper to handle 1000A, per NEC.

Copper is the better choice. *Understand that NEC tables are largely based on what is around the wire (insulation or other materials, whether it's in a raceway or not), and their values reflect that. It's a question of not catching things on fire (aka liability) around the wire, even though the wire itself can handle much more current than they say.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
You should follow whatever electric code is enforced in your jurisdiction - regardless of what is better.
No code, only 25mm² minimum, mean you can use even 500mm², no aluminium wire prohibited, but for aluminium, minimum is 35mm², also gov's utility is like to use 50mm² aluminium to ground transformer
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
From a conductive standpoint, the specific resistivity of each is (@20C):

Copper: 10.37 Ohm's per cmil/ft
Aluminum: 17.02 Ohms per cmil/ft

A cmil is 1/1000th of an inch.

A 3AWG copper wire will handle up to 313A* if ambient is 0C. Aluminum of the same AWG will only handle 248A*.

You would need 2/0 AWG Copper to handle 1000A, per NEC.

Copper is the better choice. *Understand that NEC tables are largely based on what is around the wire (insulation or other materials, whether it's in a raceway or not), and their values reflect that. It's a question of not catching things on fire (aka liability) around the wire, even though the wire itself can handle much more current than they say.
No NEC is forced, It's China, anyway is nice answer, I don't think that before
 
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MisterBill2

Joined Jan 23, 2018
9,308
The ONLY advantage of not using copper wiring is that aluminum wire is cheaper for the installer to buy. There is no other benefit at all. It will overheat at connections when current flows, and it will corrode in any location where there is oxygen present. These problems will certainly lead to all of the problems described previously.
Using it for a safety ground where current does not flow may be acceptable, possibly. But all of the anti-corrosion procedures must be followed to assure a reliable safety ground. And it may not be accepted by the electrical code in some areas.
 
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Thread Starter

meowsoft

Joined Feb 27, 2021
471
My target is make less than 2.5 ohm ground system, measured from MDP earth busbar to soil, of course I need very big ground conductor, earth panel to MDP panel is about 15meter circuit, earth panel to each earth electrode is about 2 - 8 meter circuit, earth panel busbar capacity is about 1000amp, 4x 4mmx50mmx250mm
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
The ONLY advantage of using copper wiring is that it is cheaper for the installer to buy. There is no other benefit at all. It will overheat at connections when current flows, and it will corrode in any location where there is oxygen present. These problems will certainly lead to all of the problems described previously.
Do you mean aluminium ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
From a conductive standpoint, the specific resistivity of each is (@20C):

Copper: 10.37 Ohm's per cmil/ft
Aluminum: 17.02 Ohms per cmil/ft

A cmil is 1/1000th of an inch.

A 3AWG copper wire will handle up to 313A* if ambient is 0C. Aluminum of the same AWG will only handle 248A*.

You would need 2/0 AWG Copper to handle 1000A, per NEC.

Copper is the better choice. *Understand that NEC tables are largely based on what is around the wire (insulation or other materials, whether it's in a raceway or not), and their values reflect that. It's a question of not catching things on fire (aka liability) around the wire, even though the wire itself can handle much more current than they say.
It's that mean 50mm² can handle more than 160amp ?, and do you think 1.5mm² one core wire with 24a capacity is derated about 14a in conduit nor pipe is about this ?, do you think over current in ground wire is possible ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
YES! This was an error !! I did indeed forget to add the "not" ! So much for being infallible!. I have corrected the error and now it makes sense. Thanks for catching the rather large goof.
Right... but in my area, aluminium cable is still massive for overhead 20kV also from transformer to meter, meter is suddenly burnt is not rare, I think because this problem, inside meter direct connection that connect copper and aluminium together
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
Difference country difference system
This is why in China copper thieft isn't massive than US, because overhead cable is use aluminium not copper, I don't know how they connect copper and aluminium in substations, 200kV overhead wire is aluminium but busbar is pure copper
 

MisterBill2

Joined Jan 23, 2018
9,308
Aluminum wire for overhead distribution is used in the US, but that is not the same cheap aluminum wire that was used in houses. In addition, that aluminum distribution is much more carefully terminated with the proper connection hardware. And all of that is outside where a bit of heat is not such a problem.
The transition from aluminum conductors to copper requires special techniques and also some special chemical compound to avoid problems like corrosion. So while it can be done it is not just a simple thing to do it correctly.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
471
Aluminum wire for overhead distribution is used in the US, but that is not the same cheap aluminum wire that was used in houses. In addition, that aluminum distribution is much more carefully terminated with the proper connection hardware. And all of that is outside where a bit of heat is not such a problem.
The transition from aluminum conductors to copper requires special techniques and also some special chemical compound to avoid problems like corrosion. So while it can be done it is not just a simple thing to do it correctly.
Yes... but in meter also use aluminium XLPE insulated wire, and there is no special connector or something in smart meter terminal block
 
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