Aluminium wire for ground

Thread Starter

meowsoft

Joined Feb 27, 2021
607
Over current in a ground wire is certain if there is a hit.
Yes... if ground wire is melted when hitted by lightning what's can happen ?, can someone touch metal case of refrigerator electrocuted, because is connected to same ground network
 

nsaspook

Joined Aug 27, 2009
13,086
Yes... if ground wire is melted when hitted by lightning what's can happen ?, can someone touch metal case of refrigerator electrocuted, because is connected to same ground network
With proper grounding this shouldn't happen at a industrial site.
I've been inside facilities (TEMPEST level RF shielding and grounding) designed to take direct lightning strikes without equipment harm. Other than a very loud boom, nothing happened to us, the wiring or the equipment
holt-helix-1501.jpg
 

jean_neau

Joined Apr 7, 2020
2
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
The main problem in using stranded aluminium cable is making reliable connections. Aluminium is a rather reactive metal which will quickly form a tough insulating layer when exposed to ambient air (oxygen). Also aluminium cables, for the same ampacity are stiffer than their copper equivalents, which make them a bit more difficult to work with.
However, reliable connections can be made using a strict procedure which mainly involve the use of an application specific paste e,g, an «oxyde breaker» which will «break» the insulating layer and prevent future oxydation . The same cleaning/pasting protocol must also be used for the application specific bimetal lugs. Following the lug's manufacturer instructions is thus of outmost importance... https://www.incore-cables.com/assembling-aluminium-cables/
If humidity is a concern, the use of a glued heat shrink sleeve would also be advisable. In the presence of water, aluminium in contact with copper, steel, etc. will corrode by electrolysis. Traces of white powder is a sure sign of corroded aluminium...

Aluminiun cables and busbars are extensively used in high power applications, in industrial and utlility applications, where infrared cameras are routinely used to access the reliability of aluminium connections. However, in the case of grounding cables, this method is obviously not possible since they do not normaly carry currents... A microOhmmeter might be usefull...
I would not recommend using parallel connected cables for grounding applications since the fault current might not follow the expected path. Should a resitive path develop in the parallel aluminium connection(s), a severe short circuit could then melt the copper cable...
Finally, remember that steel bolts or washers used to secure lugs to busbars shall not carry current since steel has a much lower current capacity (much higher resistivity). Steel bolts should strictly be used for mechanical purposes: keeping the electrical connection tight...
 

Thread Starter

meowsoft

Joined Feb 27, 2021
607
The main problem in using stranded aluminium cable is making reliable connections. Aluminium is a rather reactive metal which will quickly form a tough insulating layer when exposed to ambient air (oxygen). Also aluminium cables, for the same ampacity are stiffer than their copper equivalents, which make them a bit more difficult to work with.
However, reliable connections can be made using a strict procedure which mainly involve the use of an application specific paste e,g, an «oxyde breaker» which will «break» the insulating layer and prevent future oxydation . The same cleaning/pasting protocol must also be used for the application specific bimetal lugs. Following the lug's manufacturer instructions is thus of outmost importance... https://www.incore-cables.com/assembling-aluminium-cables/
If humidity is a concern, the use of a glued heat shrink sleeve would also be advisable. In the presence of water, aluminium in contact with copper, steel, etc. will corrode by electrolysis. Traces of white powder is a sure sign of corroded aluminium...

Aluminiun cables and busbars are extensively used in high power applications, in industrial and utlility applications, where infrared cameras are routinely used to access the reliability of aluminium connections. However, in the case of grounding cables, this method is obviously not possible since they do not normaly carry currents... A microOhmmeter might be usefull...
I would not recommend using parallel connected cables for grounding applications since the fault current might not follow the expected path. Should a resitive path develop in the parallel aluminium connection(s), a severe short circuit could then melt the copper cable...
Finally, remember that steel bolts or washers used to secure lugs to busbars shall not carry current since steel has a much lower current capacity (much higher resistivity). Steel bolts should strictly be used for mechanical purposes: keeping the electrical connection tight...
Ok... it is also good for use copper ground wire in parallel for AWG 0000 or bigger ?
 
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