If you are working with electrical feeders, you are probably acquainted with the electrical feeder size chart. This is an NEC chart (you will find it below) that tells you what size copper or aluminum wire to use for different amp services.
Example: What feeder wire size do you need for 200 amp service? Simple. You just check the NEC feeder sizing table and see that, for 200 amp service, you will need either a 2/0 AWG copper wire or 4/0 aluminum wire.
For adequate feeder sizing, you have to consult the said National Electric Code (NEC) chart. You will find this chart under the NEC Article 310.12 titled ‘Single-Phase Dwelling Services and Feeders’.
Obviously, it’s not all that easy to get your hands on the new 2022 NEC guidebook. That’s why we list the wire sizes for feeders ranging from 100 amp to 400 amp services, in accordance with the NEC 310.12 chart here:
Feeder Sizing Table (100-400A Services, Copper And Aluminum Wire Sizes)
|Feeder Amps:||Copper Wire Size:||Aluminum Wire Size:|
|100 Amps||4 AWG Copper Wire||2 AWG Aluminum Wire|
|110 Amps||3 AWG Copper Wire||1 AWG Aluminum Wire|
|125 Amps||2 AWG Copper Wire||1/0 AWG Aluminum Wire|
|150 Amps||1 AWG Copper Wire||2/0 AWG Aluminum Wire|
|175 Amps||1/0 AWG Copper Wire||3/0 AWG Aluminum Wire|
|200 Amps||2/0 AWG Copper Wire||4/0 AWG Aluminum Wire|
|225 Amps||3/0 AWG Copper Wire||250 kcmil Aluminum Wire|
|250 Amps||4/0 AWG Copper Wire||300 kcmil Aluminum Wire|
|300 Amps||250 kcmil Copper Wire||350 kcmil Aluminum Wire|
|350 Amps||350 kcmil Copper Wire||500 kcmil Aluminum Wire|
|400 Amps||400 kcmil Copper Wire||600 kcmil Aluminum Wire|
This table is quite easy to use. For example, let’s say you are trying to figure out the feeder wire size for 300 amp service. By checking this table, you can see you will need either 4/0 AWG copper wire or 300 kcmil aluminum wire to provide for a 300 amp service.