Electrical - 3-0 Copper
3/0-AWG Stranded Black Copper THHN Wire
Southwire SIMpull 3/0-AWG Stranded Black Copper THHN Wire
https://www.lowesforpros.com/pd/Southwire-SIMpull-3-0-AWG-Stranded-Black-Copper-THHN-Wire-By-the-Foot/50101592 $3.01 - 10% bulk - 10% sale
The distance through the conduit from the main panel to the sub-panels in the house is about 210 feet. I need 8 wires.
May be best to use Aluminum, eg http://www.lowes.com/ProductDisplay?partNumber=10155-295-13107808&langId=-1&storeId=10151&productId=3127469&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1
Need to check it is ok to used jacketed cable in conduit.
Need to ask local electrical inspector what wire gauge they require.