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Do fuses work at all?

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This is the 2nd time I have had a 300a ANL fuse blow at 150a (a cheap one and a name brand). Yester day I hit 150a and blew 1 fuse and the other looks burnt but still works. I'm starting to think that fuses just don't work at all maybe that's why homes no longer use fuse boxes and moved to breakers. I also noticed that my 2/0 wire gets hot on both sides of the fuse but not at any other point on the wires. Not even the wires on my shut have any heat at all.
Maybe I should replace all my fuses with DC breakers?
 
Use only REAL Fuses, no name knock offs are not worth a plugged nickel. Eaton/Bussman fuses will do exactly what they are supposed to and when.

IF the lugs on youe wires are hot, they may not be tight enough (crimp) or not attached tight enough to the fuse block. The other reason would be, is that they are undersized for the load they are carrying.
 
Steve_S said:
Use only REAL Fuses, no name knock offs are not worth a plugged nickel. Eaton/Bussman fuses will do exactly what they are supposed to and when.

IF the lugs on youe wires are hot, they may not be tight enough (crimp) or not attached tight enough to the fuse block. The other reason would be, is that they are undersized for the load they are carrying.
Click to expand...
Is this a no name because this is what I lost at 150a?

Amazon.com: Bussman ANL-300 Anl Current Limiter Fuse - 300 Amp : Automotive

Buy Bussman ANL-300 Anl Current Limiter Fuse - 300 Amp: Fuses - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
I also use 2/0 wire and a hydraulic crimper
 
Eaton now Owns Cooper & Bussman - ALL Top Quality product.

I've seen hydraulic crimpers flubb it, it's not hard to do.
 
If you had 2 different type fuses blow early .... then it's probably not the fuses causing the problem.
Even though you used a hydraulic crimp tool, maybe something went wrong and you have a bad connection that is causing heat and causing the fuse to blow.
 
Bob B said:
If you had 2 different type fuses blow early .... then it's probably not the fuses causing the problem.
Even though you used a hydraulic crimp tool, maybe something went wrong and you have a bad connection that is causing heat and causing the fuse to blow.
Click to expand...
The first fuse blew back when I had 2awg wire and the wires got hot all down them. This fuse blew with my 2/0 wire and only the wire on each side of the fuse get hot, move 2 inches down the wire and its cold. I have already cranked down the bolts so it cant be the connection. I use pure copper lugs and a hydric crimper. I crimp the wire down so much that the wire just past the lug is rock hard and will not bend anymore. There can be no other point of frailer but the fuse, no other point in my system do the wires get hot. I use the same wire and lugs and crimp them the same way.
 
Per the data sheet, it should take about 10 seconds to blow at 300A. It should never break at 150A.


It is, however, NOT a time-delay fuse. If you hit a current surge, such as charging a capacitor bank, say 1,000 A, it will break in a few dozen milliseconds.

All that said, 2/0 isn't good above 200A, and 2 awg isn't suitable above 100A. Assuming you're using the fuse to protect the wire from overheating, you should be using a smaller fuse.

Also, just to verify, are you using a proper fuse block to mount everything? I've seen people just bolt these to the wires free hanging, and that places stresses on the fuse that will cause it to blow early.
 
PsychoticEpisode said:
This is the 2nd time I have had a 300a ANL fuse blow at 150a (a cheap one and a name brand). Yester day I hit 150a and blew 1 fuse and the other looks burnt but still works. I'm starting to think that fuses just don't work at all
Click to expand...
fuses most certainly work, and work much better/faster than circuit breakers...

even if you had undersized wiring and a poor crimp, it would need to be "really"(like insanely) bad to generate enough hit to cause a fuse to melt.
Sadly with the proliferation of "cheap copies" it can be difficult to get the real thing, and using Amazon is certainly NOT a guarantee of quality; amazon will let pretty much anyone sell anything.

If you have a local marine supply shop consider getting a fuse there as a test.
Did you double check that your 2/0 cables are actual copper 2/0awg cables and not CCA (copper clad aluminum should be translated to mean "junk")? Also check your crimps...
something else is going on, that your 2/0 wire are hot is certainly pointing to the area where the problem probably exists.
 
Sounds to me based on what you posted is that its working as designed. Once your wire is bigger than your fuse (which is the whole point of the fuse to protect the wire) then the fuse by definition is the limiting factor of the circuit. Therefore the area around the fuse should heat up while the wire stays cools. In order to blow the fuse it has to get hot enough to melt the filament. Sounds like you have something that is pulling high current enough to blow the fuse. If you replace the fuse with a breaker please post back. It will be interesting to see if the breaker trips as well. Its really hard to detect in rush current with affordable equipment other than a fuse or breaker tripping. If you have inductive equipment (motors etc) that could come into play.
 
How are you measuring that only 150A is going through the fuse to blow it? It's possible your measurement is not accurate and in fact 300A+ is going through the fuse and its blowing by design.

The ends of the 2/0 cable getting hot would be unlikely to happen at 150A unless there are bad connections somewhere which you seem to have eliminated - comes back to the current measuring.
 
trevor.the.van said:
How are you measuring that only 150A is going through the fuse to blow it? It's possible your measurement is not accurate and in fact 300A+ is going through the fuse and its blowing by design.

The ends of the 2/0 cable getting hot would be unlikely to happen at 150A unless there are bad connections somewhere which you seem to have eliminated - comes back to the current measuring.
Click to expand...
Or that fixture the fuse is mounted on.
 
Steve_S said:
Use only REAL Fuses, no name knock offs are not worth a plugged nickel. Eaton/Bussman fuses will do exactly what they are supposed to and when.

IF the lugs on youe wires are hot, they may not be tight enough (crimp) or not attached tight enough to the fuse block. The other reason would be, is that they are undersized for the load they are carrying.
Click to expand...

This should be the time current curve for this fuse , to read it find your fuse at the top 300a approx marked in yellow , any current to the right of this curve will rupture the fuse, the higher the current the faster it will rupture, any current below or to the left of the yellow line is the normal operating range and current , the 150 amp line drawn in green is well within the blue are and extends to the top of the graph meaning this will operate continuously

hope this helps therfor you have another problem or the fuses are marked incorrectly or are not Eaton Bussman/Quality fuses
1623718498134.png
 
The problem is NOT the wires, the fuse gets hot then passes the heat to the wires. That is why the wires touching the fuse are hot but not further up the wire. If the wires were the problem ALL of them would get hot not just at the fuse. I also have 2 shunts on my system a victron and a Aili voltmeter, they can not both be wrong. There is no way My system could pull more than 300a that would kill my inverter, mppt and some of the batteries. So there is only 1 of 2 it can be, 1 it was not a real Bussman fuse or 2. Bussman no longer makes good fuses.
 
PsychoticEpisode said:
The wire chart shows that 2/0 should take up to 300a

Wire Size Chart for Conductors in Free Air

Wire Size Chart: Allowable Ampacities of Conductors in Free Air - 30C
wiresizecalculator.net
Click to expand...
Conductivity as a literal ‘capacity’ rating is not the same as calculated voltage drop and amp rating in practice.
I’m not an electrician or EE and don’t calc these things all the time so I would have to look up info and formulas and would probably double check myself multiple times LOL. But the ABYC chart for DC wires/cables saves the math. In fact it’s been so long since I’ve calculated wire size with a calculator because of using this chart I can’t even remember what book I used to reference the the formulas anymore.

The ABYC <3% loss chart for DC conductors indicates 200A.

Real world unrelatexperience:
Using ABYC chart 12V winch cables don’t usually get hot.
Other general charts like wiresizecalculator.net seem to run along NEC calcs and “charts” but often when those usually smaller cables are used, cables during a good heavy pull get hot. Sometimes even shiny. There’s also a consideration of voltage and if the load is not DC that is not factored into these general charts.
(2/0 works for a lot of winches mostly because the advertised horsepower is so often way optimistic or a downright lie since 5HP should 3750W, ~300A at 12V and so many won’t trip a 250A breaker for quite a while at near-stall.)
 
PsychoticEpisode said:
So there is only 1 of 2 it can be, 1 it was not a real Bussman fuse or 2. Bussman no longer makes good fuses.
Click to expand...

Or #3.

That crappy fuse holder is heating up and melting the fuse due to poor connections.

One of the Amazon reviews calls it a fire hazard above 130 amps FWIW.
 
Last edited:
I am a HUGE fan of solder. Yes crimp but then solder.
A lot of my back round in wiring cars . With vibration and things going from hot to cold sooner or later the connection can fail.
Soldering after crimp insures a much better connection long term.
I also like to use diaelectric where I can on bare connectors.
 
Northernchateau said:
I am in wiring cars . With vibration and things going from hot to cold sooner or later the connection can fail.
Soldering after crimp insures a much better connection long term.
Click to expand...

actually in boats/cars, with a fixed connection (ring terminal to bolted connection, battery terminal to battery) wherever vibration exists, soldering a terminal can lead to wire breakage long term.
A weathertight sealed crimp is much better.
 
I had a look at the Amazon holder and there was no data for that unit , so i checked Bussman which was similar but still very little , what this system relies on is surface to surface cable lug to tag connection, if there is little surface contact area or your not using washers to spread the load over the surfaces heat will be generated, same if your stacking lugs this could also generate heat, you cannot post a pic of your assembly could you, it must work as there are to many manufacturers using similar systems Blue Seas is another that comes to mind



1623763150203.png
 
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