Metric wire size for 1000 amp Generator

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WorkinginIraq

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I am a site manager building the police training facility for the Iraqi's. My third country national electrical engineer told me I need 4 runs of 300mm2 (592.1 KCMIL) for each phase. The runs are about 30ft long from the generator to the manual transfer switch. I did some research in the code book and online and it seems for that distance one run of 300mm2 per phase and neutral would work. Could someone validate this for me?
 
Lets call it 600 kcmil.

Under the NEC one run would be about 500 amps, two runs about 1000 amps.

I would go with the engineers suggestion,
 
Im not trying to create a shortcut or cheat the government out of money. There is no specification on wire size or count. Most thrid country nationals that call themselves engineers would never make it through an American high school. Im just doing my best to verify what is correct. The same engineer specified a 4x150mm2 wire for a 200amp sub panel. That wire is so big it wouldnt fit into the panel. I do appreciate all the information. I am doing this job because I believe in what we are doing here.
 
WorkinginIraq said:
Im not trying to create a shortcut or cheat the government out of money. There is no specification on wire size or count. Most thrid country nationals that call themselves engineers would never make it through an American high school. Im just doing my best to verify what is correct. The same engineer specified a 4x150mm2 wire for a 200amp sub panel. That wire is so big it wouldnt fit into the panel. I do appreciate all the information. I am doing this job because I believe in what we are doing here.
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But it does not appear you have any training in the NEC either. :confused:

How did you come up with a single 592 Kcmil as good for a 1000 amps?
 
WorkinginIraq said:
Im not trying to create a shortcut or cheat the government out of money. There is no specification on wire size or count. Most thrid country nationals that call themselves engineers would never make it through an American high school. Im just doing my best to verify what is correct. The same engineer specified a 4x150mm2 wire for a 200amp sub panel. That wire is so big it wouldnt fit into the panel. I do appreciate all the information. I am doing this job because I believe in what we are doing here.
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I'm inclined to agree with you. 4x300mm2 does seem excessive.
Unless it is 70degC PVC single-core in conduit buried in an insulating wall and derated for 50degC operation. That arrangement would be 1140A. The next size down, 240mm^2, gives just 995A with the same installation method.
Per BS 7671 - Requirements for Electrical Installations.
 
iwire said:
But it does not appear you have any training in the NEC either. :confused:

How did you come up with a single 592 Kcmil as good for a 1000 amps?
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I don't think he did.
The 592.1 kcmil is the conversion from 300mm2.
He is being asked to put in four per phase.
 
nawao said:
Three runs of 300mm2 cooper is ok
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I am not used to using mm2 to spec conductor. The NEC table 310.16 lists
300 kcm 75C at 285 amps and about 300 mm2. Using 3 ckts would be 855 amps. What does your code list the conductor ampacity as? 400 kcm is shown as 378 mm2 and ampacity at 335 amps 75C x 3 = 1005 amps.
 
bob said:
What does your code list the conductor ampacity as? 400 kcm is shown as 378 mm2 and ampacity at 335 amps 75C x 3 = 1005 amps.
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There seems to be some problem with the conversions used.
As I understand it, one cmil is the area of a circular conductor with a diameter of 1/1000 inch.
A little bit of arithmetic and 25.4mm = 1 inch gives about 2kcmil = 1mm^2.
So 400 kcm would be more like 200mm2.
 
I errored in reading table 8 conductor property. 300 kcm is 201 mm2 and 500 is 336 mm2. 3 500 kcm = 380 amps x 3 = 1140 amps
 
WorkinginIraq said:
Im not trying to create a shortcut or cheat the government out of money. There is no specification on wire size or count. Most thrid country nationals that call themselves engineers would never make it through an American high school. Im just doing my best to verify what is correct. The same engineer specified a 4x150mm2 wire for a 200amp sub panel. That wire is so big it wouldnt fit into the panel. I do appreciate all the information. I am doing this job because I believe in what we are doing here.
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as far as "making it work" the nec will give correct sizing for safety,
however, the national electrical code is for north america, not iraq... what
do THEY specify? or do they?

wiring that is acceptable in other parts of the world wouldn't fly here...

these photos are from india, and it looks different than what turns up in
california....

IndiaPower01.jpg


IndiaPower03.jpg
 
Fulthrotl, brings up a good pt. I've some interesting stuff form difnt parts of the world. I can't seem to find the pic from my brother-in-law, from China, a MV cable comes out of an open manhole, runs down the street for 1/2 a block, then dissappears into another manhole. Only this time the lid is setting on the cable, in traffic! =)

What about ambient temps? Laying it on the ground? (probably) buried, or aerial? MV cable or just what ever is laying around? Do you have any control over the quality and actual execution of the work? (probably not) I feel these would be real world factors that I would want to consider outside whatever NEC related concerns you have.
 
The 300mm is between 500 and 600KCM cable size.

Just one head up the tempture rating may fall in diffrent than what the NEC will say especally if in international areas that will show up diffrent and the type of conductors may not be the same as what we used to see in North America side.


someone mention 150mm that is between 250 and 300 KCM size

Merci,Marc
 
bob said:
I errored in reading table 8 conductor property. 300 kcm is 201 mm2 and 500 is 336 mm2.
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There's something not quite right here.
I looked into this some and there appear to be conflicting figures available so I went back to the basic definition to do the calculations myself.

As I said before, my understanding is that one cmil is the area of a circular conductor with a diameter of 1/1000 inch.
This gives a conversion of 1mm2 = 1.973 kcmil.
This is as posted by Eric Stromberg in an archived post from this forum dated 30th September, 2007.
see here
That would make 300kcmil = 152mm2

With a little help from Google, I found this site:
http://www.dolphins-software.com/PDF/ConductorSizes.pdf
This agrees with your 201mm2.

And this which agrees with mine

I'm sure there's some explanation for the conflicting figures.
 
Besoeker.,

I am glad you bring up the point there and Unforetally there is some conflect with the " hard " metric converison.

I did have Europeian verison of the chart vs the AWG size and it is written in one of my older notebook which I keep for over 20 years and I used it pretty often.,

Normally I will useally put in soft metric numbers { so that way it will be pretty close but not excat number }

However for the ampcapitcy rating that is a whole diffrent ballpark of game to dealt with it due have more than 5 diffrent tempture rating have to deal with it.

Merci.

Marc
 
frenchelectrican said:
However for the ampcapitcy rating that is a whole diffrent ballpark of game to dealt with it due have more than 5 diffrent tempture rating have to deal with it.
Merci.

Marc
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Je vous en prie, Marc.
Permitted current rating depends on a number of variables including cross-sectional area of the conductor, insulation material, number of cores in a multi-core cable, installation method, operating ambient, armoured, non-armoured, type of overcurrent protection device etc. I'm sure you know all that. My point is that these are specific to the application.

Unless my calculation, and that of others are in error, converting 300 kcmil to 201 mm2 gives a conductor with a larger cross-sectional area. I don't know why. If you go metric, are different operating conditions specified?
Otherwise, it seems to be just an error in the arithmetic.
 
Fulthrotl said:
these photos are from india, and it looks different than what turns up in california....
Click to expand...
I have seen these before. One of my friends sent them to me with the comment:
"And this the place we call for technical support??"
I ought to explain that in UK, much of the telephone technical support from ISPs it outsourced to India.
 
The ways that that NEC and BS7671 size cables are different, and thus I dont believe you can use one to size cables from the other.

I assume this installation is used Steel Wired Armoured cable?
 
Assuming it is SWA, then I reckon (BS7671 table 4D4A) a pair of 300sqmm 4 core cables in parallel, providing you can keep the cables in free air, so on trays, or cleats or ladders. 300sqmm in free air is capable of handling 510A.

The issue I worry about is the high ambient temperature in deserty places, as the tables assume a 30C ambient and a 70C conductor operating temperature. If the ambient was 50C then a derate of 0.87 applies, so the 510A becomes 443A so you would need more copper. What is the ambient temperature out there?
 
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