I’m putting two 100 amp sub panels in a new ‘addition’ that is nearly as large as the original house itself.   The addition creates two new spaces, one to be used as a ‘shop’ and one as an apt.  I’ve been told to use SE #4 wire to carry the load from the main to each of the subs.  Also, that this is a line that encloses four wires: two hots, a neutral, and a ground.  But when I go to purchase it — SE #4 — they show me a single woven copper cable enclosed in black plastic.  So, what is it that I need to know to get the right cable to carry this load …. up to 100 amps from main panel to sub?

Also, is it necessary to have two lines from the main, one to each of the subs?  Or is it possible to have one line to the first sub, and then a branch line from this off to the second?  I’m just putting all of the lines in place and will have a licensed electrician actually hook everything up in the end.

Thanks!

nb