Protect the CW80

I have searched the forum for inline fusing of the CW80 transformer and it seems as though a 5 amp fuse is what I found most offen. My question is would this inline protection be for the red terminal to the center rail only or would I need one for the black terminal to the outside rail also?

John

Just one for the center rail.

Thank you very much. I thought it might be but being new to this stuff I am a little afraid to just try things.