In-line Fuse Size

I am interested in using the 2005-F-34 Solenoid to open and close a wood furnace damper, and I want to protect it with the appropriate sized in-line fuse. The fully seated current is 0.43 amps, but I am unclear what the typical in-rush current is. At what current will the coil actually melt under continuous use? If the damper jams so the plunger is partially out, the steady current will be higher than 0.43 amps, so I need a fuse size small enough to protect the coil, but large enough to avoid blowing under normal use. Would a 0.5A slow blow be appropriate, or would a larger fast acting be best?


More comprehensive information is available in this document from the manufacturer’s website.

The pull-in current is seen to be rather substantial, roughly 10x the seated current at full extension. Maximum rated coil temperature is 155°C.

You may wish to see this post and the document referenced therein to better acquaint yourself with fuse ratings.

Long story short, fuses are a sufficiently sloppy technology that by the time you leave enough margin to avoid nuisance tripping under normal conditions with that sort of load, they’ll likely fail to trip under some set of genuine fault conditions. Something like a 1A slow fuse in conjunction with a thermal switch of this sort might cover more of the bases, but at some point the additional complexity will lead to a less reliable solution compared to just building a good mechanism and fusing with intent of keeping the supply wiring from glowing in the case of a shorted coil.