I was going to pull a permit and do it myself, have added circuits in sub-panels before and have a general awareness of electricity. Anyway, I pulled open my main outside panel today to take inventory and decided I was too old (smart?) to be playing around with a live wire coming in the top... even though I would be turning off the main breaker. So... I was thinking about doing pre-work to make it less expensive (hopefully). I have no fear of crawling around in an attic Situation - Primary circuit panel is outside next to driveway. 200A main. It's next to the meter. Wires come into the house through back of box using what looks like a 1 1/2" or 2" nipple, stuffed full. Garage is finished, so wires go into a drywall cavity and up into the attic through the top plate. Outside is stone veneer, so difficult to put in another nipple and would rather not rip out all the drywall. I have two sub panels - 50 amp each - on the far side of the garage. Wired with romex. Was considering putting in a sub-panel (on the near side of the garage) so I would have future expandability with the fancy HPWC balancing feature. May just put in a NEMA 14-50. Would leave breaker sizing (and wire sizing) to electrician. House is gas heat & hot water, LED lighting, etc. I'll leave that to someone else to decide how much I can get out of it Service upgrade is not possible w/o ripping out driveway and trenching to transformer. Questions - Given the finished garage and stone veneer, was wondering if I could put in metal or pvc conduit up from the box, into the attic through the soffit to use as a wire chase. And if so - Would I have to continue the conduit all the way to the new sub panel and use THHN? Or can I use 8' of conduit as a chase into the attic and pull (or have electrician pull) romex through the chase and let it continue through the protected attic and down inside the drywall wall to the sub-panel? Is metal or PVC preferred? I've read the FAQ (thanks FlasherZ). The use of romex inside conduit and the related temp derating isn't clear to me. Is there anything else I need to look out for?