On the fan should be a label that tells the amps. use a fuse for that load rating. If everything is wired correctly, I would think a 5 amp fuse should hold. Brian Denning <i_am_cool_fred@xxxxxxxxxxx> wrote: what size fuse should i run on my booster fan for the heat? i am wiring it up this weekend. _________________________________________________________________ Search for grocery stores. Find gratitude. Turn a simple search into something more. http://click4thecause.live.com/search/charity/default.aspx?source=hmemtagline_gratitude&FORM=WLMTAG