Originally Posted by ManWonder
it just surprised me that with the thickness of the wiring i tapped into they fused it at 1 AMP - so I got to thinking this might be a dedicated fuse for the detector and no harm might be done if i added another load and changed out the fuse accordingly - i could have put an inline 1 amp fuse ahead of the detector to protect it from harm
Although I agree that it is best to just run another wire, the reasoning you state above is not wrong, and some of the opinions offered on this thread are a bit overstated.
Fuses are not intended to protect devices, they protect WIRING. If in fact the wire in question has an ampacity rating of 10 amps, then it is perfectly safe to protect it with a 10 amp fuse. It really makes no difference that the propane monitor uses much less current--it will only take what it needs. BUT
, you need to be absolutely sure that the ENTIRE CIRCUIT is rated for 10 amps. The design engineer may well have taken advantage of the protection of the 1 amp fuse in order to safely cut a corner somewhere. It is generally easier to run a new wire than it is to trace the circuit in order to ensure this.
It is not unusual to find a fuse that was spec'd to the load rather than the circuit. This provides an extra margin of protection and is generally considered best practice. If this is the ONLY reason why the fuse is small, it is perfectly OK to upsize it. But it is often no easy task to determine that with confidence.