I'm doing some personal research on the specifications for cables that can handle megawatt power draws. As an example, the wires needed to supply 450VAC @ 2000A (0.9MW). I'm looking for wire diameters and insulation requirements.

Rough ballpark values are suitable for my needs. I'm not worried about voltage drops, temperature considerations, or the like.

I'd rather not pester people with this every time I want to try different voltages and/or amperages, so an online resource would be appreciated (suitable for a lay reader would be ideal but I'll try to work around something geared for actual engineers).

  • \$\begingroup\$ voltage drops and associated temperature limits are what control your "ball-park values"... \$\endgroup\$
    – Solar Mike
    Commented Sep 23, 2018 at 16:07
  • \$\begingroup\$ Is this a 1milliSecond pulse? or a steady draw? \$\endgroup\$ Commented Sep 23, 2018 at 16:21
  • 1
    \$\begingroup\$ Steady draw. As for the voltage drops and temperature limits, are there some common values I can use as defaults? This isn't for something I'm actually looking to build or anything, I'm just trying to get a sense of the types of cables such power draws require. \$\endgroup\$ Commented Sep 23, 2018 at 16:31

1 Answer 1


There are numerous current capacity or ampacity tables and voltage drop calculators online. Both metric and American Wire Gauge (AWG) are covered as well as wire temperature and voltage ratings. You may need to consider parallel conductors or bus bar at 2000 amps. In the USA, the tables provided in the National Electrical Code (NEC) must be used for ampacity. Tables are valid for a specific maximum ambient temperature look for derating factors in footnotes for higher temperature. Note also that the number of conductors in a conduit or raceway must also be considered. That is covered in NEC. Electrical codes in other parts of the world likely have similar tables and requirements.

  • \$\begingroup\$ Thanks for the answer as that seems to be what I'm looking for. However, all I can find when I search seems to be geared for residential purposes (e.g., 200A rather than 2000A). Maybe I'm just using the wrong keywords or something. Can you point me to somewhere that provides those tables for the higher power levels I'm researching? \$\endgroup\$ Commented Sep 23, 2018 at 16:24
  • \$\begingroup\$ IIRC there are usually the formula equivalents for the tables to enable on to extrapolate - the tables are only shown for the most common ranges. \$\endgroup\$
    – Solar Mike
    Commented Sep 23, 2018 at 16:34
  • \$\begingroup\$ Are you looking for USA or elsewhere? \$\endgroup\$
    – user80875
    Commented Sep 23, 2018 at 17:10
  • \$\begingroup\$ USA. I did find this: usawire-cable.com/pdfs/NEC%20AMPACITIES.pdf Am I in the right ballpark with this? For example, I see the entry for Copper, 90C, 750A. It has an AWC value of 2000 which will give me what I want in a pinch (I'm not writing a dissertation or anything). However, I can't find anything for that gauge with respect to dimensions or the amount of insulation (I'm guessing that will depend on the voltage pushing those amps through that particular strand of copper cable). \$\endgroup\$ Commented Sep 23, 2018 at 17:28
  • \$\begingroup\$ The table you found is the one to use for the conditions stated in the table. On that same web site, you can find details for various products. I believe the nominal OD is the diameter including the insulation. You will need to search to find a product with the desired voltage rating and wire gauge. The NEC can be accessed read-only at no charge at NFPA.org. You need to open an account with name and email. \$\endgroup\$
    – user80875
    Commented Sep 23, 2018 at 18:00

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