I've heard bad talk about fusible links in a wiring harness. Rebel, EZ, and others are popular but have a fusible link. Ron Francis and Painless have maxi fuses. Which one should be considered when buying? Posted using the Full Custom H.A.M.B. App!
What bad talk? I have a Rebel Wiring Harness with a fusible link in one car and a Quik Wire that I put a maxi fuse in another, factory harnesses used fusible links, if you like the Rebel Harness and don't trust a fusible link, just substitute a Maxi Fuse.
If there is a problem and the fusible link blows the wiring harness will have to be spliced to replace it. This isn't something that you may want to do on the side of the road. A maxi fuse provides the same level of electrical protection and is much easier to replace. The maxi fuse also provides a way to shut off the electrical system if needed...like if the car is stored, theft protection or working on the wiring. The only downside to a maxi fuse is that they are big and ugly. This isn't much of a problem if it is hidden but that makes access a problem. Once again style and function run head on into each other.
I've never seen a fusable link or maxi fuse to be the problem when they do go. Fusable links are usually in very accessible places and do require splicing but not much digging. Fusable links provide a much cleaner instal and less (shorter) wire than running from point to fuse to point. You'll be fine with either, just as fine as the multiples of millions who've gone before you.
Fusable links have been known to catch fire before they stop making a connection, thats why they are no longer used. If I'm not mistaken there was a demonstration on the HAMB showing one catching fire. I'm trying to find it. Go with the breaker or fuse.
The bigger issue than type of circuit interrupter being used is finding and fixing the problem that caused the fused circuit to blow in the first place. Especially one of such high amps as are typically found in the circuits that use 'fusible links' or 'maxi-fuses'. Detecting and correcting the cause is paramount before proceeding. Ray
Some info on Fusible Links (and more) here: http://www.dragzine.com/tech-storie.../top-ten-wiring-tips-with-ron-francis-wiring/
Fusible link in my DD failed partially open to a high resistance. Alternator would charge the battery just enough through the damaged link to work in daily use, but a heavy load like trailer brakes would drain the battery flat since the alternator could not supply enough current for the heavy load through the partially failed link. First time I shut off the truck, not enough battery charge left to crank and start. Was not fun to find the link and replace it. I put maxi-fuses in my hotrods.
I'd like to see it too. And there's plenty of fusable links that didnt blow. They go because of a dead short usually. Dead shorts come from poor routing, poor support, poor design or grommets, shitty repairs that ignore bracketry, modifications that don't quite fit. Yes there are time when the best still fail but you can find many more that lasted the life of the car and then some. You can even head to the bone yard and salvage them for 2 lifetimes.
The problem with Maxi Fuses is that they only go up to about 100 Amps or so-Starters on high Compression Engines can pull a lot more than that-
35WINDOW - Thanks for (non-fusible) link. I have seen fusible links used on wire from alternator to starter in case of a alt failure, even when car not in use. then a Maxi fuse on hot from starter to rest of system.
I did put one of the resetable circuit breakers coming from my alternator. Put it in a place its hidden but I can reach it easy enough.
I just called my friend Thomas who is an electrical engineer. He said the problem isn't with the fusible link, "its guys like you that wire your own cars", and I take that as a compliment. He said, "When you wire in a fusible link the entire circuit from the line side thru the load side must be done using non-flamible and non melting insulation for the entire length of the wire". "Also the wire must be the maximum gauge rated for the link". "By using plastic insulated automotive wire you are asking for trouble". So I guess the bottom line is, that if you can locate and use the proper wire, it's up to you, it's your car.
One trip up the hill with my travel trailer (electric brakes) to find the problem. Battery dead at the first gas stop. Jump start from good samaritan, back on the road, things seem normal. But as soon as I hit the trailer brakes, voltmeter on dash showed low voltage. Aha! Charge not getting from alternator to battery/dash. Had a 10ga piece of wire in the toolbox to direct connect the alternator and battery, which fixed the problem and told me I had a connection, wire or link problem in the harness. When I got home I found the partially failed link and fixed it right.
This is some good information. I'm currently finishing off the wiring in my '55 Cameo with an EZ system. The kit includes a fusible link that is installed in the fuse panel feed from the starter (at the starter). I'm concerned ever having to change it on the road so am planning on installing an in-line fuse. I like the idea of the resttable breaker. Would someone be able to advise what amperage breaker I should use? There are no markings on the fusible link that came with the kit. Thanks in advance.
In my opinion, you'll need at least as much amp capacity as required by as many of the 'loads' fed by your fuse panel. In other words, add up the loads (use the fuse capacity of each circuit is one way to do that) of as many appliances as you can imagine using at a given time. For example, headlights, heater/AC blower, wipers and so on. As long as each circuit is separately fused, and they are, any particular circuit that suffers an overload will only take out it's own fuse, but a major catastrastroke will blow the fusible link/maxi-fuse. Ray
Fusible links and fuses aren't the same thing, and both need to be installed with some care. The key to understanding them is knowing how they work; and remember that any fuse/overcurrent device is there to protect the wire. A fuse is designed to blow once current through it reaches 100% of it's rating. And when it blows, it blows quickly (within a few seconds if not faster). A fusible link can withstand maximum current for a longer period before blowing (minutes rather than seconds; think of it as a sort of slow-blow fuse). So why the difference? Fusible links became popular because the manufacturers could scrimp on harness wire sizes in circuits where anticipated overloads were relatively short enough in time that damage to the wire could be prevented by a fusible link. In other words, the link would blow before the wire melted. So a wire that could normally take 20 amps but might see 40 amps briefly (but would become damaged if you tried to run it at 40 amps for an extended period) could be protected by a link. Fuses don't offer that type of protection. They'll pass all current up to their rating, then blow. You also have to size them at 125% of the anticipated load to prevent nuisance tripping; once you go over 80% of their rating, a transient current spike can blow them. So in the above example if you substituted a fuse for a link, you would need a fuse rated at 50 amps (not 40) and that 20 amp wire would get the full 40 amps (and melt) if the 'temporary' overload went on too long. As I said above, a fusible link is basically a means by which the harness designer can use undersized wire for the circuit (and save money) and hopefully prevent the harness from catching fire. Not a good substitute for a properly-designed harness.... For more on harness design, wire ampacity, and overcurrent sizing, look here.... http://www.jalopyjournal.com/forum/threads/wiring-101.843579/
All the manufactures used fusable links for many years. Yes most of them never failed, but why use something that can start a fire. Use maxi fuses , they are much easier to replace as well
4-8 wires in a traditional engine compartment (excluding the front lighting harnes.) where traditional fusable links go. Maybe 12 if you have extra crap in there. Late model engine compartments have nearly 200 wires where late model maxi fuses are found. Use what you feel comfortable with, look into Crazy Steve's posts here and wiring 101 for more in depth info, its very good
The maxi fuses or fusible links aren't supposed to blowing at a frequency that makes changing them easily very important. That's just some really backwards cowshed rationalization.
? The solenoids draw no where near that...what. maybe 15 to 20 amps or so? Surely you wouldn't be "linking/fusing" the main cable from the battery?
Well, I don't know how 'traditional' fusible links are as they didn't come into widespread use until the sixties... It's obvious that some still don't understand the difference between a fusible link and a fuse. While both are a form of overcurrent protection, there's two different reasons for using one or the other. A fusible link will tolerate an overload before blowing; how long depends on the amount of overload and how much time the overload is there. The higher the overload, the sooner it blows. A link properly sized and installed will prevent damage to the wire it protects. Can they be a fire hazard? Absolutely... The one thing they do poorly is clearing dead shorts, as some damage can occur before they melt. But replacing a link with a fuse, while it will improve performance when clearing a short, will mean that you don't have overload protection, only protection against dead shorts or very high current. A fuse will only blow when current exceeds it's rating. In other words, if you have a failure where the current draw is above the wire rating but below the fuse rating, the fuse will allow that wire to 'cook' until you do have catastrophic failure. Again, a fusible link will clear this sort of problem before the wire is damaged if it's properly sized. If you're being furnished with a fusible link with whatever harness kit you bought, use it. This also tells you two things; one, the wire is too small for the anticipated maximum load but considered adequate for the anticipated 'normal' load and the seller is aware that the wire is small.
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