Choice between CU and AL cables

[maypot]

Hi,

What is the best choice from a technical point of view, between three 240 mm^2 Aluminium single core cable/phase and one 3 cores 300 mm^2 /phase. It is also understood that both options can carry the load current .
Thks.

Bob

 

[RalphChristie]

Can you please rephrase your question?

Do you mean a choice between three single-core 240mm² cables (aluminium) or one three-core 300mm² (copper) cable?


Check

http://www.ccbda.org/publications/33e-publication.html

for some advantages of copper above aluminium. The one disadvantage of copper is cable-theft, and that can be a big determinating factor. But copper would be my first choice if burried in the ground.

However, if you state that cable sizes, I will prefer single-core cables. Single-cores are much easier to handle and will also terminate easier in a box. What about single-core copper cables?

 

[advidana]

use copper it is easier to install and less problems after installation. al cost less since that is also important but is handles less ampacity than copper so be careful for cost comparison.

 

[mc5w]

You can also go to

http://www.sefcor.com

and get aluminum lugs that are intended to be WELDED onto the end of aluminum conductor using the tungsten inert gas welding method.

It takes about 6 times as much heat to weld copper as it does to weld aluminum. From the standpoint that welding is the best way to make an electrical connection aluminum is a better choice.

However, you cannot use weldment lugs on underground cables that run at over 600 volts. The alternate method is to clean up the strands with #220 silicon carbide abrasive paper, treat with joint compound, and then recompress that strands with a hose clamp.

Please go to my website http:/home dot earthlink dot net/~mc5w for directions on how to make up aluminum wire connections that have ALL the wire strands conducting using the silicon carbide paper, elbow grease, electrical grease method.

 

[kjn]

Don't forget a major consideration is weight: quite true that Al ampacities require larger conductors than Cu, but once conductor sizes approach 300 kcmil/MCM there is a clear advantage to field pulls of AL because it is much lighter.

modern Al conductors have alloy additions overcoming many historical disadvantages, very common to find lugs Cu-Al rated.

 

[ScottyUK]

If you require 240mm² aluminium, could you manage with 185mm² copper singles? You don't state load current or installation method so it is hard to be certain. 300mm² 3-core copper will be a massive cable: you will need serious manpower and / or a power winch to install it. Your field guys will hate you. From a practicality point of view, I would use the 3x single cores. Be careful with your glanding arrangements if you use singles.



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If we learn from our mistakes,
I'm getting a great education!

 

[mc5w]

However, for what copper costs you can put in twice as much aluminum cross section and have it run cooler and have less voltage drop.

A lot of times with a duct bank that is underground or across the ceiling it does not cost that much extra to throw in a few extra conduits. A lot of the cost has to do with supports and trenching.

You can also use wireway as a totally enclosed nonventilated version of cablebus. One way to get in a pulling string is to attach jetline to a toy car or tank that is radio controlled. For 6 inch busway a lot of toy racecars can be fitted with some steel strap underneath that fits inside of the wireway.