replacing fusible link with breakers. What do i need to know (1 Viewer)

[mudgudgeon]

I'm currently rebuilding my 1fz-fe, and tidying up my engine bay and accessory wiring while the engine is out.

PO has replaced the main 100amp fusible link with a 100amp maxi-blade fuse in an inline fuse holder.
Its been kind of poorly done and I want to remove it. I accidentally shorted battery cables while working on stuff, and popped this fuse.
I tried several spares shops for replacement fuse, and had to order spares in (not great if a fuse blows in the back of nowhere(

I've got OEM fusible links on backorder with Toyota Japan. The 6-8week delay in sourcing replacements has me thinking about replacing all the fusible links with circuit breakers at the battery.

I know enough about them to make myself look silly. So I'm looking for tips. I did search, found some helpful stuff, but nothing directly related to replacing fusible links.

Part of my thoughts is that having a breaker pop while on a trip, you give it time to cool down. Investigate for a problem that may have caused it to trip, and then if all good reset, and you're mobile again.

I believe there's different types of breakers, with some that cope with momentary spike in current. Beyond that, not really sure what else I need to know.

Is there any inherent disadvantages of circuit breakers that would rule this out as a feasible solution?
I know initial cost is gonna be a lot higher than using fusible links. I'm more interested in a foolproof solution that isn't relying on me carrying spare fusible links, or having to do a trail repair on a blown link?

 

[bhsdriller]

How often do you expect to replace them or have them go bad?
My stock has lasted 230k and if the replacement lasts just as long i'll never drive it enough miles to wear it out

 

[landtank]

Maybe give this guy a call. Cruiser Wiring - http://www.globalsoftware-inc.com/coolerman/fj40/wiringmainframe.htm

He does links on the older Land Cruisers and is accommodating to request.

 

[White Stripe]

Fusible links are a bit more forgiving. They burn out slower than a circuit breaker. So a circuit breaker would trip more easily. That's how I understand it. I've also considered doing going to circuit breakers but it's not high on my list right now.

 

[MoJ]

I'm currently rebuilding my 1fz-fe, and tidying up my engine bay and accessory wiring while the engine is out.

PO has replaced the main 100amp fusible link with a 100amp maxi-blade fuse in an inline fuse holder.
Its been kind of poorly done and I want to remove it. I accidentally shorted battery cables while working on stuff, and popped this fuse.
I tried several spares shops for replacement fuse, and had to order spares in (not great if a fuse blows in the back of nowhere(

I've got OEM fusible links on backorder with Toyota Japan. The 6-8week delay in sourcing replacements has me thinking about replacing all the fusible links with circuit breakers at the battery.

I know enough about them to make myself look silly. So I'm looking for tips. I did search, found some helpful stuff, but nothing directly related to replacing fusible links.

Part of my thoughts is that having a breaker pop while on a trip, you give it time to cool down. Investigate for a problem that may have caused it to trip, and then if all good reset, and you're mobile again.

I believe there's different types of breakers, with some that cope with momentary spike in current. Beyond that, not really sure what else I need to know.

Is there any inherent disadvantages of circuit breakers that would rule this out as a feasible solution?
I know initial cost is gonna be a lot higher than using fusible links. I'm more interested in a foolproof solution that isn't relying on me carrying spare fusible links, or having to do a trail repair on a blown link?

I’ve wondered the same. I like the idea of being able to troubleshoot without having to replace the link each time. Particularly if you’re in BFE and only have one or two spares.

 

[mudgudgeon]

How often do you expect to replace them or have them go bad?
My stock has lasted 230k and if the replacement lasts just as long i'll never drive it enough miles to wear it out

Well, mine had done about 200k km (130k miles) when I bought it, and the PO had obviously installed blade fuse a good while prior to that.

I accidentally popped the blade fuse with a silly mistake.
Finding that it was not immediately available at several parts stores does not inspire anymore confidence than the average job of wiring in a fuse holder does.

 

[mudgudgeon]

I've read enough stories of people caught out by toasted fusible links that I think there's possibly a better solution.

I get why fusible links are used from a manufacturing stand point, cheap, compact, minimal labour cost in incorporating then into wiring harness.

If life to understand what the pros and cons are.

It may ultimately not make sense, but I'd like to understand why.

In regards to fusible links being slower to blow, I believe there's differences in functionality in circuit breakers too, just as there is with fuses. Not all fuses are created equal.

I know circuit breakers can be made to tolerate short spikes of current well in excess of constant current ratings

 

[Njck22]

Fusible links are incredibly reliable and will fail safe. I would run them even if you move to circuit breakers. Put the circuit breaker downstream of them and see if you have any problems over a few trips. If a circuit breaker starts malfunctioning you can then bypass it.

But honestly how many people have ever blown a fusible link, that wasn’t falling apart from age/corrosion? Because the number of issues that could blow one of them is pretty small and obvious, having a spare is more than adequate because if you blow a fusible link that was in good shape you got other problems.

 

[Hornd]

First Are you Running Dual Battery or Noco? Higher Probability of Loss due to Battery Failure
Then Pack extra EFI Relay and Extra Fusible Link.
If you go thru 2 Fusible Links. You have a Direct Short that needs addressed Right then

 

[sxp]

I replaced a fusible link with a breaker years ago on an old square body GMC. The link controlled power to the headlights from the starter (or something like that). It worked fine, and I would know when it tripped because the headlights would blink. I never found out what the original problem was with the wiring. I assumed it was a bare wire or similar.

 

[smritte]

I've been running manual reset breakers for decades in my off road vehicles. Fuse links work, fuses work, breakers work (no auto reset). The advantage to fuse links is size, the disadvantage is unless their properly supported, they break. A fuse link is just tinned wire with a fire proof coating, two sizes smaller than the wire its protecting.

I already have a breaker feeding my remote panel in the back. The rear panel is all breakers, my fuse links will be all breakers soon.

 

[Azca]

Is there any inherent disadvantages of circuit breakers that would rule this out as a feasible solution?
I know initial cost is gonna be a lot higher than using fusible links. I'm more interested in a foolproof solution that isn't relying on me carrying spare fusible links, or having to do a trail repair on a blown link?

Fuses are more precise in their clearing times as compared to circuit breakers. They come in a variety of styles (classes) which can be tailored to your application. A breaker is more of a one size fits all application. When it comes to protecting equipment, fuses are more desirable than fuses and do a much better job at protecting equipment. On the other hand, for critical (assured) operations, a breaker is superior as it usually can be reset. As an example, hospitals will use circuit breakers for the vast majority of their distribution system because they can be reset and replacement fuses are not always handy. Industrial users will use fuses to protect equipment so the devices can be tailored to suit their needs and provide superior protection for equipment that may cost millions of dollars.

The fusible link which is little more than a fuse without a body, will melt in an attempt to protect downstream equipment. The obvious issue is you will need a replacement fuse when this occurs. The problem with this is, what happens if you did not clear the fault or overload before replacing the link? Now you burn up your spare and are stranded.

The alloys used in the link are unknown so how it designed to react is unknown. Fuses are made with specific types of alloys, sometimes encased in a medium, that provides predictable melting times and may help reduce fault current depending on the fuse type. When you look at different fuse classes and their time-current curves, you will see the curve as a line. These are very predictable devices. When you look at a circuit breaker, which operates by distortion of a metal, the clearing times are not nearly as clear and appear as a band. The band signifies the range, or time, that it takes to clear the device. Not nearly as precise. For this reason, fuses can more easily be coordinated so that the downstream fuse opens first and only clears the faulted circuit.

Breakers are not as reliable as fuses as they are mechanical devices. We all know that mechanical devices fail due to lack of maintenance, environmental issues and manufacturing issues. The more adverse the conditions, the more likely a failure occurs. Fuses are static devices, for the most part they work or they don't. Also note, while it is rare, fuses do fail. If a fuse is compromised, it may not melt (open) as designed. If using breakers, use the best devices such as the Blue Sea systems (made by EATON).

Final consideration regarding breakers vs fuses. Under an overload, a breaker can be safely reset. After a fault, and depending where the fault occured, the breaker may need to be replaced. Depending on where and what faulted or shorted out, the breaker can be subjected to huge amounts of heat and mechanical forces that can damage the breaker internally. Obviously we can't see inside the breaker to detect the damage. Closing or resetting the device, if subject to high amounts of current can be dangerous. A damaged breaker can turn into a hand grenade when reclosed, even if the fault has been cleared. A standard car battery can turn out 300 amps of current (short circuit current or fault current) when shorted at its terminals. Breakers have an "AIC" rating, which is the amount of current they can safely clear, or close on and clear, under a faulted condition. The AIC rating of the breaker you chose should be at least as high as the amount of short circuit current supplied by your battery or batteries if used in parallel. (Fuses also have the same ratings and requirements). If a fault opened the breaker, next to the breaker, it may have been damaged. Wear gloves when resetting and turn away from the device so if it does rupture, you will minimize the amount of harm to you.

Also note that breakers should be exercised to assure proper operation by tuning on and off. Yes, this includes the breakers at your home!

Both devices have their inherent advantages and disadvantages. In the end, you need to decide what is more important to you, operational reliability or the protection of your electronic systems. For us, a breaker supplying a fuse block may be the best of both worlds. You can reset the breaker to the fuse block and the fuses provide superior equipment protection downstream of the fuse. For me, I am working on my system now and using a combination of fuses and breakers. I will also carry a spare breaker just in case.

 

[MoJ]

Fuses are more precise in their clearing times as compared to circuit breakers. They come in a variety of styles (classes) which can be tailored to your application. A breaker is more of a one size fits all application. When it comes to protecting equipment, fuses are more desirable than fuses and do a much better job at protecting equipment. On the other hand, for critical (assured) operations, a breaker is superior as it usually can be reset. As an example, hospitals will use circuit breakers for the vast majority of their distribution system because they can be reset and replacement fuses are not always handy. Industrial users will use fuses to protect equipment so the devices can be tailored to suit their needs and provide superior protection for equipment that may cost millions of dollars.

The fusible link which is little more than a fuse without a body, will melt in an attempt to protect downstream equipment. The obvious issue is you will need a replacement fuse when this occurs. The problem with this is, what happens if you did not clear the fault or overload before replacing the link? Now you burn up your spare and are stranded.

The alloys used in the link are unknown so how it designed to react is unknown. Fuses are made with specific types of alloys, sometimes encased in a medium, that provides predictable melting times and may help reduce fault current depending on the fuse type. When you look at different fuse classes and their time-current curves, you will see the curve as a line. These are very predictable devices. When you look at a circuit breaker, which operates by distortion of a metal, the clearing times are not nearly as clear and appear as a band. The band signifies the range, or time, that it takes to clear the device. Not nearly as precise. For this reason, fuses can more easily be coordinated so that the downstream fuse opens first and only clears the faulted circuit.

Breakers are not as reliable as fuses as they are mechanical devices. We all know that mechanical devices fail due to lack of maintenance, environmental issues and manufacturing issues. The more adverse the conditions, the more likely a failure occurs. Fuses are static devices, for the most part they work or they don't. Also note, while it is rare, fuses do fail. If a fuse is compromised, it may not melt (open) as designed. If using breakers, use the best devices such as the Blue Sea systems (made by EATON).

Final consideration regarding breakers vs fuses. Under an overload, a breaker can be safely reset. After a fault, and depending where the fault occured, the breaker may need to be replaced. Depending on where and what faulted or shorted out, the breaker can be subjected to huge amounts of heat and mechanical forces that can damage the breaker internally. Obviously we can't see inside the breaker to detect the damage. Closing or resetting the device, if subject to high amounts of current can be dangerous. A damaged breaker can turn into a hand grenade when reclosed, even if the fault has been cleared. A standard car battery can turn out 300 amps of current (short circuit current or fault current) when shorted at its terminals. Breakers have an "AIC" rating, which is the amount of current they can safely clear, or close on and clear, under a faulted condition. The AIC rating of the breaker you chose should be at least as high as the amount of short circuit current supplied by your battery or batteries if used in parallel. (Fuses also have the same ratings and requirements). If a fault opened the breaker, next to the breaker, it may have been damaged. Wear gloves when resetting and turn away from the device so if it does rupture, you will minimize the amount of harm to you.

Also note that breakers should be exercised to assure proper operation by tuning on and off. Yes, this includes the breakers at your home!

Both devices have their inherent advantages and disadvantages. In the end, you need to decide what is more important to you, operational reliability or the protection of your electronic systems. For us, a breaker supplying a fuse block may be the best of both worlds. You can reset the breaker to the fuse block and the fuses provide superior equipment protection downstream of the fuse. For me, I am working on my system now and using a combination of fuses and breakers. I will also carry a spare breaker just in case.

Any performance advantage between a typical automotive fuse and a fusible link?

 

[fjbj40]

Personally I prefer breakers. I am an aircraft mechanic, 99.9% of electrical protection is done by circuit breakers.

I have never seen a breaker not do it’s job in 35 years. The only time I found faults in a CB is when they were exposed to the environment and corrosion killed it.

I have adapters made with circuit breakers that I use during electrical short troubleshooting.

Personally I would not hesitate to replace the fusible links with the aerospace type breakers, but they would need to be protected from the environment under the hood.

 

[Azca]

Any performance advantage between a typical automotive fuse and a fusible link?

I work in the building industry so I would not have much specific information on vehicle DC systems. That said, there would be advantages to going to a fuse vs the link if nothing else but ease of use to change them out when they fail. I am certain you could find specific fuses that may lend themselves to quicker response or even instantaneous but not would not believe those to be acceptable for vehicles as high inrush current (especially motors such as a compressor or LEDs) could cause nuisance tripping (opening of the circuit). A time delay fuse would be a better choice but, there are multiple levels of fuses (classes) that fall in this category. Again, I could not spec out a specific fues without researching them and have not gotten to that stage myself.

My only word of caution is to find a fuse type that is readily available. While certain advantages could be obtained by using the fuse of your choice, it will do you no good if you can't find it when you need it. As with all fuses, carry spares! I carry a minimum of two replacements for each fuse size in the vehicle. And store these in a dry place!

 

[Azca]

Personally I prefer breakers. I am an aircraft mechanic, 99.9% of electrical protection is done by circuit breakers.

I have never seen a breaker not do it’s job in 35 years. The only time I found faults in a CB is when they were exposed to the environment and corrosion killed it.

I have adapters made with circuit breakers that I use during electrical short troubleshooting.

Personally I would not hesitate to replace the fusible links with the aerospace type breakers, but they would need to be protected from the environment under the hood.

View attachment 2825256

View attachment 2825258

Excellent example of a breaker's superiority to a fuse in a specific application! Not sure if these are accessible to the pilots but, on the surface, finding the right fuse at 30k feet in a stressful situation might be a tad difficult!

 

[Azca]

One final word, place the fuse or breaker as close to the source of power as possible. The conductor between that power source and the overcurrent protective device in only protected against overload, not a short circuit. Car-B-Qs are created this way...

 

[mudgudgeon]

The problem with this is, what happens if you did not clear the fault or overload before replacing the link? Now you burn up your spare and are stranded.

These two things is what has had me thinking about breakers.
I've thought about them previously knowing I have a sub-par repair in place, but having blown the main fuse recently, its really highlighted what I was already aware of, sourcing replacement specialised fuses is problematic. Right now, my car is mid engine rebuild, so it hasn't mattered.
Sourcing OEM or OEM style fusible links is problematic. My local dealer told me two weeks.
I ordered some through another supplier along with other parts from Toyota Japan, and these are on backorder with Toyota.

I like the idea of being able to reset or open a breaker during fault finding. There's been times in the last where I've blown multiple fuses trying to find and repair a fault.
If this happened with the fusible links while away from home, it could definitely lead to stranding

My only word of caution is to find a fuse type that is readily available. While certain advantages could be obtained by using the fuse of your choice, it will do you no good if you can't find it when you need it. As with all fuses, carry spares! I carry a minimum of two replacements for each fuse size in the vehicle. And store these in a dry place!

This is my main consideration. I've also thought about replacing fusible links with another type of fuse, but choosing one that is readily available in auto parts stores limits options.

 

[mudgudgeon]

Personally I prefer breakers. I am an aircraft mechanic, 99.9% of electrical protection is done by circuit breakers.

I have never seen a breaker not do it’s job in 35 years. The only time I found faults in a CB is when they were exposed to the environment and corrosion killed it.

I have adapters made with circuit breakers that I use during electrical short troubleshooting.

Personally I would not hesitate to replace the fusible links with the aerospace type breakers, but they would need to be protected from the environment under the hood.

View attachment 2825256

View attachment 2825258

Thanks, that is helpful.
Any particular type or brand you would suggest?

 

[fjbj40]

Thanks, that is helpful.
Any particular type or brand you would suggest?

I have access to them, free from old aircraft that are no longer in service, you will find them expensive to purchase!

However, you might find used units on eBay and such.

Here is the style and a well known manufacturer but there are others out there that do just a good a job. KLIXON 7277 CIRCUIT BREAKERS | Aircraft Spruce Canada - https://www.aircraftspruce.ca/catalog/elpages/klixon7277.php