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B-lead fusibl link. How to make it

JDA_BTR

Well Known Member
I?m looking for advice for the best way to build and connectorize a 10gauge wire protected by a 14g fusible link. B&C sd40 connection to the main contractor.

Contemplating if I really need a 8ga with 12 link but it seems too much.
 
I like to use terminal ends for the fusible links and attach them with #6 or #8 machine screws and nuts.
I also make an extra link to keep in the plane just in case.
If it?s under the cowling, you can use a couple tie wraps and stand offs to mount it along a motor mount tube for a nice installation that you can get at later.
 
Everything's a compromise. Connectors make it easy to change out the link. But what are the odds of needing to change one? The only way a properly sized link will 'blow' is a catastrophic fault to ground downstream of the link. Now, what are the odds of a mechanical connection (actually, 4 connections) developing a high resistance or open circuit fault?

The link needs to be at the supply end of the wire (in this case, toward the battery end of the wire). Putting it somewhere in the middle leaves any length upstream unprotected.

Crimps are fine, but so is solder, if done right (I soldered the splice from wire to link on mine).

Don't forget that if the link does blow, the insulation (even tefzel) can disappear along with the wire. Unless this is planned for, it could let the still hot end touch something else. And with an alternator, both ends are actually 'hot'. If you do some searching, you can buy fuselink wire in various gauges that has thick, hi temp insulation specifically designed to contain the heat/flame.

For my installation, I used a ring connector on one end of the link, attached to the battery contactor. I soldered and heatshrink insulated the joint between link & wire.

FWIW,

Charlie
 
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From reading the automotive forums, the consensus is that a fuselink is marked with its actual size. So a 14 fuselink protects a #10 wire.
 
It'll work fine, but try not to overthink stuff like this. You can achieve the same thing using a straight 8ga butt splice, and adding a bit of stranded wire to the 12ga fuse link wire, to get roughly the same cross section as 8ga wire. A typical 8ga crimp will have a range of wire sizes. If you get one that's rated for 8-10 ga wire, that tells you that you don't need to get the wire size perfect for the crimp to be gas tight. As long as you add enough extra strands to get the 12ga up to somewhere between 10 & 8 ga, and use a proper ratcheting crimper for that crimp splice, you'll be good to go.

Charlie
 
BandC sent me a ?current limiter? that was actually a marine product available in any marine catalog. It was inexpensive and worked out great. I want to say that the brand was ?Blue sea? but can?t remember exactly.
 
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