for the "always hot" wire going to the relay for my bottle heater do i connect the fuse holder to the end of the wire that connects to the battery or the other end which is at the relay? thanks.

 

connect it closest to the power supply..which in your case would be the battery..

 

thanks

 

What heater do you have? I have the NX auto heater and it didn't come with any fuse...should I put one in there and what size?

 

i always fuse any of my connections..i dont think mine came with a fuse i cant remember, but i put one in anyway..i think i went with a 25 amp.. you will thank yourself later when the fuse blows instead of the wire melting the insulation all the way through you car and possibly catching something on fire.. if you do a good clean install there is probably a 98.9% chance nothing will ever short out but just in case of a component failure or whatever a 3 dollar fuse holder is good insurance on anything electrical..