Electrical Fuse Link Assessment

[DuderMcMerican]

Hey duders,

I'm having trouble assessing my fuse link situation. My questions are as follows:

1. How can you tell when a fuse link is bad? I read others saying that it will stretch and break. The colored wire pieces of the links seem stretcher than other wires, but...

2. I get ~0 ohms when checking resistance across the link. Is resistance testing appropriate in this situation? Could there be continuity present but still be a trashed fuse link? Should i also do voltage drop tests?

3. Fuse link anatomy: Which part of the link is the opetational component? Is it the rigid black piece that says "fuse link," or is it the colored wire that the black piece connects to?

4. Is it normal to find plastic-y hard goop to be around the edge of the rigid black piece? It looks like it's been melted, but i don't know... It's on several of my links. Please refer to pics to see what i mean.

Thanks!

 

[jrichker]

1.) The test for fuse links is to use the ohms function of the meter and measure their resistance. Make sure there is no power applied to them by disconnecting the battery negative terminal clamp. If you don't you may not get a correct reading or damage the meter

2.) Set the meter on the lowest ohm setting and short the probe tips by touching them together firmly. That is the reading you would get if you tested a good fuse link. It might be .1 to .2 ohm more that shorting the probe tips together, but no more than that.

3.) The actual fuse link is colored and it will be a different color from the wire it connects to. The black part of the wire in your picture is the heat shrink tubing that covers the joint between the fuse link and the wire it protects.

4.) The plastic goop around the edges of the heat shrink tubing that covers the joint is hot glue that oozed out when heat was applied to shrink the tubing. A more expensive variety of heat shrink tubing has a hot glue liner that melts when heat is applied to shrink the tubing.

The hot glue lined heat shrink tubing is a little more difficult to find, but a Google search will help you find it. I would use the hot glue lined stuff if I was doing something that I knew was going to be regularly exposed to a lot of water, oil or other fluids. When the hot glue liner melts, it seals the tubing so that nothing can get inside it. You would need a hot air gun to successfully work with this type on heat shrink tubing, Harbor Freight has them ( http://www.harborfreight.com/catalogsearch/result?q=hot+air+gun ) if you want an inexpensive tool to add to your collection of tools.

 

[DuderMcMerican]

Thanks, jrichker! Very informative, as always.

Regarding resistance, if I consistently get a reading of anything greater than 0.2 ohms, then the fuse link should be replaced, correct?

I do have a heat gun, and it is surprisingly useful on a regular basis.