Grannyannie - don't know which 5er model you have, but many fuse/breaker boxes are near the entry door, either in plain sight or inside a nearby cabinet, as Ladywendolyn mentioned. Also if you have the owner's manual, it should tell you where to look. Last resort, if you can't find it, email Jayco with your serial number and they can tell you where it is.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.