all heated gear is hooked directly into battery with a fuse in between of course. have never blown a fuse with top/bottom/gloves/socks all going. controller uses pulse width modulation so full amp draw doesn't hit all at once. seldom have I used heated socks .. but use heated jacket and gloves all the time. heated pants regularly. really depends on how cold one rides...
I blew one on the KLR, it was a cold mofo for a while. I really dont know why it blew, gloves and jacket liner.
At least 2 posts have suggested INSULATED heated gear. I wish I had read these before my purchase. I have an Aerostich heated jacket (not the AirVantage like SMSpiff's). I occasionally use it alone and it's a very good wind shell with some insulating capability. And the pit zips align with my shell pit zips so I can quickly ventilate when the temps warm up. BUT about 80% of the time that I use my heated jacket I wear an insulated jacket over it. It's all very versatile, but an insulated and heated layer would be so much simpler.
Another Warm&Safe vote...but whatever you get make sure it fits snug. You want those heating elements touching you, not hovering away from you!!
Just replaced my Gerbings microwire with the Warm-n-Safe Gen 4 jacket & wireless controller. The Gerbings microwire has huge areas with no heated coverage, was not to much of a issue until you have a drafty jacket. The Warm-in-safe looks to be built better, no cold spots and the wireless controller is GREAT! Plus Warm-n-safe give a HUGE ADVRider discount as well. This is gear designed by motorcyclists for motorcyclists.