Fuse rating

[Rick Loiselle]

Greetings Group,
 
If a product has a 4A rated input current (120V AC), how does one
determine the rating of the in-line Fuse for safety/Fault testing?
 
The Fuse will be used at the AC connector Inlet, inside the product (not
user accessible) on the Hot lead wire.  I do know that it will be an in-line
type fuse
holder, UL and CSA approved, 5X20.
 
We test to UL6500 and IEC 60065.
 
Best Regards, 
Rick