Can someone test the t class fuses? For littlefuse (blue sea) and south bend?

[Hedges]

I don't trust the specs of these reputable fuses either, since time and time again we see them not actually doing what they say they do. Almost every genre of device that exists has this problem

Do you have examples of them not doing what technical specs say they will do?
Or are you still hung up on the fact that a 100A fuse can carry significantly more than 100A for a significant length of time, and you think that is just wrong?

Fuses are probably more trustworthy than breakers. Breakers get stiff after a while, have higher trip current. You're supposed to periodically snap them off and on a few times to keep them loose. You do perform maintenance on your circuit breakers, don't you?

 

[rhino]

You do perform maintenance on your circuit breakers, don't you?

I periodically short my battery cables to make sure they still work.

 

[Mattb4]

hilarious coincidence he's doing testing of them
...

I tried looking at this and it is poorly thought out and hard to follow. Even skipping ahead to each segment for a few seconds. For one thing his conclusion that generic rings terminals he bought on Amazon were no good, because he could pull out the wire after crimping, simply meant he made an inadequate crimp. You have to watch for this when you have a crimper set for a thicker constructed terminal versus a thinner one of a given wire size. The Metric to Standard dimensions is also an issue frequently encountered.

Put this way you crimp the darn thing until the wire does not pull free.

I would not follow this fellow for any valid results regarding fuses.

 

[12VoltInstalls]

Metric to Standard dimensions is also an issue frequently encountered.

Yes. I have that issue. My favorite little “B” crimpers don’t always crimp amazone-sourced bare crimps because they are sometimes thin barrels, sometimes metric even if you searched for awg. This solves it for most ring terminals but of course is wrong for MC4, PL-259, various coax etc

Put this way you crimp the darn thing until the wire does not pull free.

I get so pissed off when I pull a wire out of a crimp which is why I have so many crimpers: one of them is going to make a nice shaped tight swage if I wind up with off-sized crap somehow, or if impatient I’ll just flip and crimp from the opposite side. Or if it is not a ‘fitting’ those Channelocks^^^ always make the smaller ones tight.

I would not follow this fellow for any valid results regarding fuses.

After reading this I didn’t bother watching.
There’s good stuff on the Y’Tube but there’s way more idiots trying to make a buck that neither know nor give a flying frog’s toenail

 

[scoharri]

1 of my UL listed "T" class fuse was tested naturally by failing in the system. It worked. I bought 3 more, 2 of those are spares now

 

[Hedges]

What caused the overload that blew your fuse?

 

[SupraSPL]

I compared voltage drop of a cheap Amazon 300A ANL fuse vs South Bend 250A class T fuse (full size body not the mini blue sea). The fuses were bolted directly between very heavy buss bars, no fuse carrier. From memory it was 150-200 amp load and I measured a 2% voltage drop with the ANL fuse. Not surprising, it was thin and got stupid hot. (40W of heat is that even possible). The class T dropped about 1% and also got surprisingly hot.

For control I tested that same connection with no fuse, and there was zero voltage drop, cool to the touch. All the surfaces were prepared/flattened before the test.

So if your system is 12V, under heavy load often, the class T with heavy duty body may be worth it for that alone.

 

[gotbeans]

Do you have examples of them not doing what technical specs say they will do?
Or are you still hung up on the fact that a 100A fuse can carry significantly more than 100A for a significant length of time, and you think that is just wrong?

Fuses are probably more trustworthy than breakers. Breakers get stiff after a while, have higher trip current. You're supposed to periodically snap them off and on a few times to keep them loose. You do perform maintenance on your circuit breakers, don't you?

Project Farm has an entire channel on youtube with hundreds of millions of views total dedicated to manufacturers making stuff that don't meet what they say they do

no doubt fuses are more trustworthy than breakers, I agree there. But you're fighting a losing battle, almost every manufacturer lies somewhere.
Look at air bags, it took 50 years to realize whatever that one company that just got closed down knew they were killing people

I tried looking at this and it is poorly thought out and hard to follow. Even skipping ahead to each segment for a few seconds. For one thing his conclusion that generic rings terminals he bought on Amazon were no good, because he could pull out the wire after crimping, simply meant he made an inadequate crimp. You have to watch for this when you have a crimper set for a thicker constructed terminal versus a thinner one of a given wire size. The Metric to Standard dimensions is also an issue frequently encountered.

Put this way you crimp the darn thing until the wire does not pull free.

I would not follow this fellow for any valid results regarding fuses.

naw those terminals are indeed crap, can get them on aliexpress too. It's nearly impossible to make a crimp that actually holds the wire.

 

[Hedges]

I agree some companies lie and some products are bad.
I think airbags are a bad deal, take about 1/3 as many lives as the number of (seatbelted) people they save, but required by congress. Seat belts much better.
The airbag inflater issue was criminal.

Do you have any example of Bussman, Littlefuse, other top tier name fuses failing to meet their specifications?

Given the documented spread of amperage and time, systems can be designed so they are protected by those fuses.

 

[Hedges]

The class T dropped about 1% and also got surprisingly hot.

I've got some name brand (think it is Littlefuse) class T holders, and they have cooling fins.

 

[rhino]

I've got some name brand (think it is Littlefuse) class T holders, and they have cooling fins.

https://www.digikey.com/en/products/detail/littelfuse-inc/LFT304001CS/2670456

 

[Hedges]

Yes, like that. May have only been 2 fins.
Less expensive on eBay.

I was going to add 400A class T coordinated with 200A main breaker for catastrophic shorts, but decided box volume too tight.
So they will go on battery.

 

[12VoltInstalls]

if your system is 12V

The class T dropped about 1% and also got surprisingly hot

Interesting.
Currently I’ve only got 1800W of panels running and none of my ClassT get warm.
But 1.8kW is fairly small.

 

[SupraSPL]

Interesting.
Currently I’ve only got 1800W of panels running and none of my ClassT get warm.
But 1.8kW is fairly small.

The heat will depend only on the current. In my case it was about 200 amps. It may have been as much as 250A but I'm going from memory.

 

[gotbeans]

Do you have any example of Bussman, Littlefuse, other top tier name fuses failing to meet their specifications?

Nope, this is a thread to test them. You want that data, agree to the thread

The heat will depend only on the current. In my case it was about 200 amps. It may have been as much as 250A but I'm going from memory.

Also ambient and also if you have some sort of wind flow going on.
My ambient for some fuses ranges between 30 and 100 degrees which I only assume pretty massive for their ratings

 

[Skypower]

hilarious coincidence he's doing testing of them

meanwhile half the people in this thread:



yea I got one of those nanque too, any breaker from any company can die at any time but the massive amount of testing is always reassuring.

I have to admit that immediately after watching this Louis Rossmann video I ordered the brand that tested best. I recently installed two new fuses blocks in a boat to replace the rats nest of inline fuses. The blade fuses were a collection of cheap assortments from Amazon and auto parts stores over the years and some looked kinda chinsy. There so many in the kit that I can afford to sacrifice a few in each range to verify performance. I’ve got a large selection of 5X20mm glass tube fuses I’ll doom while I’m at it. I’m going to try to use my internal resistance meter to see if there’s any correlation to blow current = non destructive testing = recategorizing. Sorry not going to blow $40 a pop on T class fuses. I do have a 5KVA variac and two turn microwave oven transformer so current isn’t the issue. One thing of curiosity, a littelfuse 300 amp fast blow has higher resistance and more voltage drop than a South Bend 250 amp fast blow when subjected to a 75 amp load. No much, a few milivolts.

 

[Hedges]

I’m going to try to use my internal resistance meter to see if there’s any correlation to blow current = non destructive testing = recategorizing. Sorry not going to blow $40 a pop on T class fuses.

If the fuses increase in resistance as they get hot, positive TCR, you should be able to find different curves for them without destructive testing. I'm sure that's easier to accomplish by first logging the curve for destructive testing. But it could be something like hitting with increasing pulses, using 4-wire resistance to determine element temperature, wait until cooled to same point for each step. Categorize according to current/time required for something like 50% resistance increase.

I did a simple test of automotive fuses to make sure they were marked correctly. The manufacturers did choose to use same element for two ratings, close enough to meet some tolerance spec:

Testing automotive fuses

After watching a video (sorry can’t find it now) showing resistance testing of cheap fuses and name-brand ones, I decided I’d better test the ones I’ve put in our cars. In the video, it was said that previously Harbor Freight sold fuses, but later recalled them and didn’t carry anymore. Fuses...

diysolarforum.com

 

[user2562]

I've got an extra Bussman Class J FWH-300A if anyone has the tools to destructively test.

 

[gotbeans]

I've got an extra Bussman Class J FWH-300A if anyone has the tools to destructively test.

Thread 'Dead short fuse trip experiment using an MRBF fuse'

Mar 16, 2024

Introduction
Marine Rated Battery Fuses (MRBFs) are sometimes used to replace Class T fuses due to supply chain issues, ease of installation, space constraints, and cost. However, the breaking capacity of MRBF fuses is significanly lower than that of Class T fuses as shown in Figure 1.


Figure 1. Ampere Interrupting Capacity vs DC Voltage Rating

Problem
How will an MRBF fuse behave when subjected to a dead short outside of the fuse specifications?

Background
If the fuse does not quench the arc, then hot plasma could theoretically turn the fuse...

• Johan
• Replies: 121
• Forum: Danger Zone! (Advanced User Experiments Only)

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there is a guy that was testing the fuses, I asked for the ones to be tested after people just laughed about it in this thread lol

I saw you made another thread, not sure on safe ways other than maybe having a bigger amp rated one you know works or just wire that will evaporate so the batteries survive

 

[Luk88]

I'd love to see that. I'd definitely chip in if they addded NH2 fuses to the test. I'm mostly interested in the difference between NH2 630V AC 400A and NH2 80V DC 400A.

But it wuold have to be a well made video, with oscilloscope traces and so on.

But something like this will not amass millions of views. So it would have to be funded by patrons 100%.