It does not appear that Lowes carries 4-gauge Romex wire. However, they do carry 4-gauge THHN (stranded) wire. You would have to purchase it by the foot (unless you want to spend $800+ for 1,000-foot spool), and you'd also need to install a new conduit for the THHN wire to run inside. That could be as simple as a flexible ("greenfield") conduit with a connector on each end. (See the image below - you can also purchase this from Lowe's.) I'm guessing your furnace runs off a double-pole breaker, so you will most likely need enough THHN cable to run 4 conductors (2 hots, a neutral, and a ground). I'd figure out your pathway, measure it, add a couple of feet to be safe, and then multiply that by 4. I'd probably purchase the green wire for the ground, and the black for the hots/neutral, and then use electrical tape on both ends of one hot conductor and a different color electrical tape on both ends of the neutral conductor so you can keep track of which one is which. Good luck...as BG said - don't work in your panel hot! Turn off the main breaker, but beware that even with that off, the feeders from the utility are always hot. Watch where your hands, screwdrivers, etc. are at all times! ** Edited by MP4VT2004 at 1/21/2026, 9:58:02 AM ** Edited by MP4VT2004 at 1/21/2026, 10:19:32 AM