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Discussion Starter · #1 ·
I have installed a new 130 amp alternator, that's protected by a Mega-Fuse. The old Ford regulator/ charging circuits have fusible links on the main 10ga wire feeding the (replaced with voltmeter) ammeter and dash circuits.

Queastion is: can I safely eliminate these from my wire harness, or at least replace them with fuses?

Trying to "clean up" the underhood wiring mess..
 

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no, you could, but you shouldn't. a fuse, will just blow, and therefor they have to be rated high enough that it won't just pop on a small voltage spike, a fusable link, will burn out, but will have to get hot enough to burn out first, it will not 'false alarm' on you.
 

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Doc here, :pimp:

NEVER eliminate a Fuse link!

Do you mean MAXI Fuse?

That IS a Fuse link (Ford type), and if it is on the Alternator output wire , that will protect that harness..

The other Fuse link protects the harness that is the support wire for the Whole electrical system and fuse buss, and should not be eliminated. A Major fire could occur if any shorts happen to the car's electrical system.

Standard Fuses will not hold up to spikes and overloads as would a Fuse link, A link requires time and heat to melt the junction..IF you can find fuses that high of a Current value.

Don't relocate the links or Maxi's to the interior of the car either..they do their job by burning up..and could cause fires to interior parts of the car, or toxic fumes could be a problem in a closed cabin. Always mount them in the engine bay away from sources of ignition.

BE SAFE!

Doc :pimp:
 

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Discussion Starter · #4 ·
It's a Mega

125 amp Mega-Fuse with it's own connector. I have an AWG 4 feed from the alternator to it, and from it to the b+ side of the solenoid. Then I ran another AWG 4 feeder to a distribution block that feeds the fusible link circuits as well as a "key-on" relay and fuse block for those circuits and another B+ fuse block for the "always hot" connections. Fan control, ignition box, horn relay, choke heater etc. all draw their power from there. I intend to make as robust as possible system.
 

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grandpaws 57 said:
a person could use one of late model underhood fuze blocks.They use a series of large fuzes.Get at salvage yard.

Doc here, :pimp:

Yeah, You are Correct, Those are located on the Relay Courtesy centers, Those ARE MAXI fuses, (same as a Fuse link) and will work as a fuse link. Those usually are 50, 65, 70, 90 and 95 amp Links, (and show as a Fuse link on the schematics)

I have one Problem with MAXI Fuses..they are too EASY to replace, just pop one in and forget about it..but , sadly , that's not always the case..There is a MAJOR reason a MAXI goes out..

one which can start a harness meltdown..MAXI's Don't just blow like a fuse can over time..There is a serious reason it went out, and many folks don't understand the difference until it's way too late.

With a Fuse Link, you have to cut wire, and solder in order to replace it, Motivates you to find out WHY it went out, before blowing it off..since you don't want to do it twice!

just my nickel's worth..

Doc :pimp:
 

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302/Z28 said:
Here is what happens when a fuse link pops, and the number one reason I do not use them. http://www.ronfrancis.com/images/chart-file14.pdf

Just me and my opinion :) .

Vince
What do you suggest as an alternate?

I've never used a fuse link in the past (wiring of auto or motorcycles) and not had any problems. Most seem to think they are the way to go now. I'm not convinced. Teach me something new / better.
 

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I use the fusible links because they were standard in the old harnesses.

But, if you've ever had one go, you get the fire and mess like the photos above. Trust me on this one. It would nice to have an easily replaceable device for the non-historically correct applications. I may check out those under-the-hood, modern day blocks.
 

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Check out www.littlefuse.com
Select "datasheets"
Then select "automotive type fuses"
Then select "MAXI fuses"

This will show a chart explaining the Time/Current characteristics for the various amp ratings.

MAXI fuses are very slow blowing at light overloads and very fast at heavy overloads. This means that the wiring can tolerate a light overload for an extended period of time but a heavy overload or short circuit the wiring will burn very fast.

They perform these rated interrupting functions up 1000 amps.

vicrod
 

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Doc here, :pimp:

While Fuse links are not the "Perfect Solution" as protection in case of a mass overload, (a Meltdown ANYWHERE is not a desirable Situation) Consider the alternative..The 3 inch link melting Vs 5 to 10 feet of Main harness Wire bundle melting down and catching fire..The Link, is designed to be "The Weakest Link" Which is where the melt down will occur..I suppose the Link will not be better suited until someone installs them in fireproof J~Boxes that mount to the frame rails..

MAXI Fuses work just fine too.AND you can get "In-line Type" of Mounts or plugs for them, so they may be mounted on the Buss current supply line.

Another Option (if you want to spend the bucks) Is an Aviation type Thermal overload type Breaker..BUT depending on the size and type of overload, it can run you from $150 to $400 bucks each ! (TSO'ed parts ain't cheap!)

Fuse Links (as well as MAXI Fuses) have been in use from the factory since the 70's..Look on ANY Vehicle schematic within that period, and you will find AT LEAST 1 fuse link shown, and on Modern Vehicles , with complicated systems , up to 20 Fuse links in use.

Whatever way you chose to go..the Link protection device is there to protect the harness throughout the vehicle or specific circuit from meltdown and/or fire in case of mass short..It is not SAFE to run without them..

A Gas or Oil fire Can be put out by chemical..Easy enough to do , and with luck not too much damage. An Electrical Fire CAN NOT!!!.. It will NOT go out until the source of Ignition is removed (or it runs out of things to burn) AND can have flash points anywhere wire runs.. You Can pour all the chemical or water on it you want, and it may diminish, until you remove the water or chemical, But until the source of ignition (the Battery) is removed, (wire burned through, or the battery explodes) It will flare right back up..Then it becomes a race as to which goes first..the battery , or your rod burns to the ground...To run without link protection (of any type, link, Maxi, or thermal overload), is "whistling past the graveyard"


LINKS BYPASSED BECAUSE "BOOM~BOX" KEPT BLOWING THEM.

Note Crime scene tape, and overhead water spray, FD waiting
until battery dies, explodes or cable melts
before it can be put out. (the car was a total loss..)



Maxi's are, as I said , Fine, It is my personal opinion, on a Vehicle where the owner or mechanic is NOT Electrically inclined, just too easy to replace them..and not investigate Why it went out..which can aggravate the problem.BUT that's my personal opinion...There is nothing wrong with using them!

IF you do use links, Be sure they are mounted in a location outside the vehicle, in an area not prone to Fuel, oil , or hydraulic lines and not around flammable parts or hot or rotating parts.. GM traditionally places them on the starter battery terminal. Not too much to burn there. When they go, they do leave a mess to clean up, but considering the alternative, which would be a main harness bundle in the same shape..is not a bad option.

Doc :pimp:
 

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My personal OPINION and previous experience has taught me to run without them for a couple of reasons, ONLY ON VEHICLES I BUILD. I would keep them in newer stock vehicles but I will get into this reason later in this post.

1 I had several problems with them in the past, and it was NOT due to electrical problems, they got hot enough where the factory and other wannabe backyard mechanics left them dangling and located themselves too close to a source of high heat (exhaust system parts) and melted where regular rated factory supplied wires, and THHN wires survived.

I built one complete wire harness from the switches, light sockets, and sensor connectors supplied from GM, but with ALL my own wires and fuses.

All wires were soldered to all other wires, or connectors where there was a need to remove part of the harness for one reason or another.

All wires were calculated to correspond to the load they were needing to supply on a regular basis, with a safety factor of 10% or so included in, and the same went for the fuses, all were calculated to provide a safety rating to a certain percentage above the normal load they were asked to allow, to as close to the rating the fuses were available at any supplier.

With that truck I NEVER had a problem in the three full years I ran it, but I never asked anything more than running lights, the ignition, the starter, and the windshield wipers on all speeds, and providing power for a CB radio at the time. I did NOT have a computer of any sorts running any parameters of the vehicle for any reason.

Now for the rest of the story:
I had the misfortune of owning a second generation Chryco minivan, and one of the many times it was knocked out of service for one of the too many pathetic reasons, I ended up tracing the electrical problem to a burned fusible link that was quick fixed by soldering a fuse into place until I could find another fusible link to replace the old one with.

I spent over a month looking for fusible link wire and tried every source that was available to me at the time, and I couldn't buy it anywhere.
I ended up taking it to an automotive electrical specialist in the area that nearly everyone recommended, with the full explanation of the problem and attempted quick fix.

The specialist had it for a week, ran every test he could on that van, and could only come up with one possible cause of that link burning up in the first place, then he repeated the test for me, burning up a link to show me what he could come up with, and then replacing that link with one rated 5 amps higher than the original, along with his explanation of the change of rating.

On the newer vehicles I own, with the ECM running several things important to actually getting the vehicle even out of park, I will leave them in and pretty much alone, as long as they do not provide a problem. Complete fabrication of a new vehicle without computer control I will leave them out.
 

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dawg said:
you can get ris of the links provided you use a circuit breaker if you know the max amperage.
I use breakers on my camaro and soon on the corvette.
if it pops ya just reset it after you find the problem.
I made a nice hidden panel with the circuit breakers for just about every circuit.
get em here:
http://www.bpbsurplus.com/lc/cart.php?target=category&category_id=324
and here
http://www.aircraftspruce.com/catalog/elpages/klixon7277.php

Doc here, :pimp:

Those are Klixon Type Breakers, I stared at those 3 to 4 hours a day before I retired from JAL Flight training Center, some 15 years ago..

Those Are the Breakers I was Referring to in my earlier post! They are very good reliable protection devices (if installed in a properly set up buss system) , I have bought and used them on Vehicle systems before (years ago) EXCEPT, then Surplus was rare, and when you found one, they were usually bad..(the mechanical reset would vibrate and trip) So I bought them NEW from our Parts department (Green tagged & TSO'ed) and They weren't Cheap!!! Even with my discount! (If you notice , on the 2 nd link, New 2 or 3 amp breakers are $35 bucks today's prices!)

Nice part about those , you can shut down offending circuits in flight simply by pulling the breakers one at a time, and resetting until you find the problem, and then leave it off, leaving the rest of the buss active. No fuses to screw with, and you Don't have to wait for it to trip, just pull the head of the breaker and it's off..

The Higher amp Klixons were also switch type , and were used for things like radio Master , Charging circuits, and other busses..

I was unaware of a surplus outlet now a days, that had them that cheap! Thanks for the link!! :thumbup:

If I can get them Cheaply, I will use them, and advise others to also!

Doc :pimp:
 
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