Bad Fuses
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- เผยแพร่เมื่อ 28 ม.ค. 2025
- This video looks at the quality - or lack thereof - of cheap, no-name automotive blade fuses.
ATC Blade Fuse Datasheets:
www.littelfuse...
www.eaton.com/...
HRA2Z companion website: a-2-z.tech/
HRA2Z Merch site: hamradioa2z.my...
Thanks for sharing this. This is taking slow-blow fuses to a new level... never-blow. I have a box of no-name fuses too and will be getting rid of them.
Why not just test them first, at least the lower amperage ones?
It's just... I too have such fuses and I know that they blew in my car at some point. 🤔
Sooo... My course of action would be to test the fuses that I can test with the equipment I have.
@@oilybrakes I can totally second that. I never got burned with cheap fuses. Some of them were a bit beyond their rating but i never got any that would never blow. Test 1-2 of each amperage and if they blow within spec, they're a keeper. Cheap isn't always bad and expensive isn't always good,
@@oilybrakes and only use the ones that blew when they should have ? Should I buy 5000 so I can take a sample large enough to get a good measure of tolerance and still have many left to use?
@@tricky778 Once you tested them, you will know that they are in spec. What else do you want?
@@oilybrakes once I know they're on spec they will not conduct. I want them to conduct.
This is not the first time I have seen this style of demonstration. I was amazed at the data that the demonstration produced. Essentially the same outcome as your test, but lacking your sophistication.
I was staying at a friends house several years ago, & I was given a spare room in their home to spend a night with them. This room was awaiting a contractor to tear out the ceiling & walls & install first grade insulation & such other work as he deemed necessary to make the room cozy in the coming winter.
My friend had purchased an electric heater (1500 watts) & it was plugged into a wall socket that was a dedicated 20 amp circuit. About an hour after retiring I awoke because of an odd smell. I sat up in bed & the electrical heater was engulfed in flames, & the power cord was burning along its length. One door in the room opened into the house proper, & the other opened into the back yard. I had left my jacket , trousers & outside boots beside the bed . I turned on the night table lamp, pulled my boots on & grabbed my coat & removed my leather gloves(work style, not "dressy" style), grabbed the handle of the heater (which was already starting to melt) , opened the outside door & heaved the heater into the yard, & then turned & pulled the power cord from the wall socket, & threw it into the yard. The rug was on fire, but it was a material that was very slow burning ( treated as "fire retardant"" & it joined the rest of the immolation in the yard. The next door neighbor saw the flames & ran into the back yard with a CO2 extinguisher & snuffed the burning bits out. My friend ran 9into the rook & did the same to the rug & we opened the two windows in the room to lose the smoke. Another neighbor had summoned the fire dept. & they & the police arrived together. The Captain declared the fire officially out (a second co2 bottle was used & they made certain the flooring beneath the rug & the wire & wood behind the melted outlet was
flame free. The fire Captain said that the Provincial Fire Marshall's office was attempting to have that particular heater banned from sale. The next day we bought a new 20 amp duplex receptacle, & I installed it . The lady of the house plugged a floor lamp into it, & turned the light on & all appeared well. I went to close the door on the entrance panel , & noticed that the dedicated breaker was open, but the light was still on ! I reset the breaker, & it was not latching. I removed the floor plate on the breaker board & removed the 20 amp breaker & took it apart, to find the contacts were welded shut !! My friend asked me what I thought. I told him that I thought that he should call a Provincially licensed contractor & have him
examine the panel installation, & anything else he deemed necessary, & to give you a report. The panel was made in China, & all its internals were as well. Most of the wiring had to be changed as well. My friend engaged his insurance company at this point, because his sister from whom he had purchased the house & who had paid a local electrical contractor to upgrade the house from a 60 amp circuit to a two hundred amp service, & it ALL had to be removed & approved equipment installed at great expense.
You never know these days.
I'm building a van and you just scared the crap out of me!!! I just order 2 big boxes of Littlefuse blades.
Thank you so much.
Glad you did this test. I had always assumed off brand fuses woukd be at least close to thier rating. Thank you.
I go to a generally recognized national auto parts store for my fuses (I generally use Bussman). The price difference between the better fuses and the generic ones is pretty minimal compared to the value the better ones provide, in the larger picture. Nice video.
Yikes!
Talk about “penny wise, pound foolish.” It’s never occurred to me that I might be using no-blo fuses. Time to do some testing!
The ones to watch out for the most are cheap no name fuses made in China. Chinese manufacturers are known for not making things within spec.
just this week I had smoke come out from under the dashboard of my car , 2 wires dead shorted and went red hot , burnt all the outer covering to a crisp , they where supposed to be protected by a 10 amp fuse , all that the fuse did was melt a little bit , but did not blow. I think the cars battery is a 60 amp. I will be replacing all the cheap fuses with brand names asap. thanks for your video.
Thanks for a great informative video. I threw out the chinesium 100 pack fuse assortment I bought over the summer after watching this video and bought Littel and Bussman fuses for my ham equipment. 73 de KH6DC
Thanks for the heads up on these fuses. I have a bunch of these fuses in a box and a few in service. I will now toss all of them.
Thank you very, very much for this video. As a motorhome owner this is very worrying as I have been using those cheap fuses for years. I have been very lucky.
I am buying a set of decent ones straight away and replacing them all. Thanks again.
I tend to be ultra “frugal” and tend to buy cheap stuff. But new to this hobby I’m discovering it just doesn’t fit to go cheap in this hobby. Thank you so much for educating me.
Thanks for the eye opening information. I've always used Littlefuse and Bussman fuses whenever possible, but now I'll stay with them all the time.
Thank you for doing this and sharing it. I have for years used any old fuse I could find (correct stated rating though). I will avoid noname fuses from here on out! Shocking results.
You've created some work for me with this video... Thank you.
Same haha...damn.
Hi, Tom. Thanks for the very informative and interesting video. Blade fuses are a type of commodity item I've never really thought twice about. I guess not all of them "just work". I'd hate to have one of those 5A no-name fuses "protecting" a sensitive circuit in my vehicle. Well done.
Marc (N1QGM)
Same here - I never thought you could screw up a fuse!
Pay attention. Any fuse like these, no matter what manufacturer, will NOT protect 'sensitive' equipment. They are only intended to protect wiring systems.
I remember a Marconi engineer looking at a duff transistor. "The three pronged fuse has blown!"
... some months ago i had my fuse box melt down while i was driving, and i had no idea how the heck it happened.
looks like i might have just found out.. ty so much, i am gonna go grab some bussmann resettables and pray they're authentic i think XD
I bought a similar pack of bargain fuses, and had some suspicion, based on the thickness of the internal conductor, that their rating was off. You just verified what I suspected, in a rather dramatic and more accurate fashion. Thanks!
Discovered the same thing about 10-12 years ago when a cheap fuse from one of those kits failed to blow when a wire shorted to ground on a motorcycle. The end result was a small fire and many hours of labor replacing the bike's wiring harness. I contacted the seller and let them know what happened; they didn't believe me.
Testing the fuses found the same thing as in this video, they just didn't open under 2x-3x their rated load.
Very interesting
I'm a mechanic and I didn't know that all fuses were not created equal
I will no longer be buying cheap fuses
Thank you
These fuses are the best kind! All the other ones blow out so fast! This is the last fuse you will ever need to buy.
I was randomly recommended this video and straight up bought spare bussman fuses (the littelfuse kits were about the same price) just now. Glad I never had to use the spares I bought a couple years ago, those will go straight to the trash. It seems like the knockoff kits spent all of their money on a case so maybe I'll put the good bussman fuses in that. Thanks!
Just shocking. Never thought the China fuses were that far off , it’s simply so dangerous that the companies that put them up for sale should be sued. Thanks for an interesting test.
I saw a doctor in china comparing medical thermometers. They were all showing different readings. China is simply too corrupt to produce quality products.
How ? are you going to sue Brandon
ESPECIALLY BRANDON!!!!
The fuses that are hard to read, don't have the rating colored white, are the ones that are not "certified " as I understand. I found a video similar to yours stating this. I trashed my assortment from Harbor Freight, and purchased a Littelfuse assortment. Great video
I have oem ones that don't have that
Some major brand in the UK, Halfords, doesn't state that they match the DIN standard, not any set of qualities with reference to it. I've no idea whether they blow as fast as they should, nor as close to the rating as they should, and they didn't promise that they would either.
I'm most impressed! Very important info. Now I got to go check my fuses. Don't forget to check what goes in your car, lots of sensitive stuff in there.
Great video! Excellent warning about cheap fuses that often get taken for granted. Please note though, that those types of heat guns observe a rather large conical region in front of them to determine the temp. They do NOT measure the point at the red laser dot. Unless one is measuring a larger area (like a frying pan for example), they are inaccurate for small spot measurements like the fuse - the fuse is likely to be much hotter than one it displays since it is averaging same of the desktop temp with the fuse. Nonetheless, awesome video. Will be sharing this with others!
This information is soo needed.
This was 101 in my day.
Trust but verify… especially when expensive equipment is involved.
Those fuses are nothing more than pretty plastic covered nails.
I suspect they're all the same, that's why spent the extra resources on the different colors
@@Eduardo_EspinozaThey certainly look it from the pics, all the wires look the same thickness
great video and a solid reminder to ALWAYS buy name brand fuses that specifically list the specs and have the UL seal of approval. Remember... you get what you pay for.
A certain company named after a major feature in South America is notorious for selling electrical devices of all sorts that don't carry any credible safety agency approval/certifications.
I think a lot of this stuff comes from companies that say "yes, we can make that" when what they really mean is "we can make something that looks like that."
I did once see a small wooden model that was claimed to be FCC certified. Now I am willing to admit that a chunk of wood is quite unlikely to generate EMI or RFI, but ...
I have several of these boxes and DID get an expected clear on fuses below 5amps. I need to test them and also would have liked to see you text the bigger no names. Guess I need to price out name brand on fuses boxes and test my cheapies
Oh great, I'm in the process of building a camper van and bought two fuse boxes on Amazon. Guess which fuses came with the box 😠
Thanks a lot for the warning!
So I tried to destroy the included 5A fuse by running the diesel heater which pulls 12A, fuse didn't blow after 5min.
Thanks for a superb video and useful warning. I'm a glider pilot and use this type of fuse to protect the wiring that runs under my seat; I can't remember where I bought them. I must figure out how to control the current from a lead-acid battery so I can check one or two of mine!
Extremely helpful video! I've got a package of Bussman fuses on order and am going to swap out all my current no-name blades as soon as it arrives. Never thought about fuses before and just assumed a fuse is a fuse is a fuse. Thank you so much for this informative video! 73!
Wow! I'm not a radio guy but really appreciate YT for suggesting this video. I recently bought one of those cheap fuse kits on Amazon to keep in my RV. Not only will I toss that kit out but I'm going to have to go through all the fuses in my coach because I've a bad feeling that the manufacturer of my RV may have used these cheap fuses. I can only wonder how many camper fires might have been caused by one of these poorly made fuses. Thanks!!!
I ditched the cheap fuses not over the (unknown to me) failure to blow, but rather over their inconsistent thickness and inability to reliably make contact with sockets.
Many off brand fuses are some random pot metal that doesn't seem to fit correctly, and have all sorts of strange geometry on the legs that you push into the sockets, compared to the Bussman, LittleFuse, and other OEM fuses that all fit snugly and have well formed connection legs.
Well I’m about to order some new name brand fuses and throw out all the no brand stuff on my bench right now.
Thanks Tom!
All this must be due to a Chinese translation problem. Where in English said fuse it corresponded to the Chinese for "heating element" 😊
Thank you for testing these fuses, and for making this video!
Those no-name fuses can come in handy since it would be difficult to get a penny in that blade fuse holder.
I'd of never thought that no name fuses would be THAT bad! I think I have some and will check them and probably through them out. Thanks for making this video. I too am a Ham Radio guy.
You have illustrated overcurrent protection in the precise way it is intended to work. The startling issue I had not expected is the lack of specification on the chinesium fuses. Very nicely done and an important warning.TNX
Tanks Tom another really informative video. Look forward to more in the future.
Fuse wire is made from a special metal alloy wire that will fuse(When any wire melts open, it is said to fuse) that is suspended between the mounting connections hence the added value.The giant bag of fuses for a dollar that I have inspected seem like the fuse wire in them is just part of the stamped out aluminium mounting blades hence no value. Great video N0̷PXJ
Thanks Tom,really good info. Never gave it a thought till now will check my that hang on wall. Thanks again.
Great job!
Sometimes a return to basic component information is invaluable. I think another component that needs examination is clone Anderson Power Points. Many of them look right, but do not use the proper materials and arc at very low currents!
Hope you'll do more things like this....
I have heard about fake PowerPoles. That’s another one I need to check into. Thanks for mentioning it.
For 44 years, I taught aircraft electrical/avionics/weapons control systems maintenance. I do not remember one new student knowing the true purpose of fuses/circuit breakers. When we got done, they knew.
Ok, you've spooked me! I like littelfuse but have some cheapo genetics. Ordering replacements now. Thank you!
This is a great bit of advice, and a nice catch. I can only imagine how many of these no-name kits have been sold, and how many devices out there are virtually unprotected due to the use of imposter fuses! As another viewer commented, some of the dirt-cheap fuses are made with some rather dubious metals that rust/corrode, and that's a deal-breaker in and of itself!
I'm not in the radio field, my interests lean more towards automotive and computers, but I've always used Littelfuse or Bussmann - leaning more towards Bussmann as the fuse bodies are more translucent and easier to see gaps. I feel more comfortable with a brand I've used for years, over some brand I've never heard of that has so many vowels that I'm not exactly sure how to pronounce it. The price differential isn't significant enough for me to "go cheap." Sometimes you really do get what you pay for!
When I first saw the 5-Amp in your test rig on the bench, my initial thought was "that link is WAAYYY too thick to be a fiver..." At a glance, it looks like a 20-Amp or 25-Amp. I know what some of you are probably shouting at your screen right now: "you can't properly rate a fuse based on looks alone," and generally speaking, yes, you're absolutely right and I wholeheartedly agree. BUT this fuse was CLEARLY not a 5-Amp, heck, it's more like a fuse-shaped link! As you so handily demonstrated, it could easily withstand multiple long-run tests at 400% rated current. I've seen heat-warped fuse blocks once in a while, in cars that I've repaired over the years. I think you might have solved the mystery for how that happens - OEM fuses pop and some "El Cheapo" fuses the owner bought shoved in to replace them.
I watch a few HVACR channels, and most RTU (rooftop units) use a 5-Amp blade fuse to protect the control boards. I might drop a note with those Creators and suggest they buy Bussmann or Littelfuse exclusively. I assume they do, since they go through commercial warehouses, but they've got businesses to run and might consider trimming overhead by buying bulk no-names.
About that fire extinguisher - you might want to get one with metal handles. I've heard stories about the plastic ones breaking during test. (Especially if you fail to properly remove the safety.) They're a little more expensive and a bit bigger, but still a good investment.
Thanks for the tip!
@@HamRadioA2Z Another tip: Get CO2 extinguishers for dealing with equipment fires. The other types will make a mess of things and potentially create a bigger problem as the electrical fire heats things up.
@@russellhltn1396 I usually reccommend Foam extinguishers. Sligthly less effective than powder, but doesn't destroy everything that the fire didn't damage.
@@HamRadioA2Z Have you ever seen the mess created by a dry powder fire extinguisher, especially in a relatively confined space?
What makes matters worse..the powder is hydroscopic, and will corrode metals if you don't vacuum every last trace.
Go dry water mist good on most fires and using reverse osmosis water it's none conductive and once dry leaves no residue
One thing you'll also find with the cheap generic no noame fuses is the blade material is thinner, therefore it doesn't have the same contact pressure and that allows resistance and heat build up. I've seen a few of thses melt in the past. I'd also check the temperature of the powerpole connectors as they are rubbish, I refuse to use them. Very disconcerting that the 5A fuse just doesn't blow at 20A though, so generally zero protection and 100% dangerous.
Could you please explain further what is bad about power pole connectors?
Thanks for taking the time to share this information! Before throwing them out, maybe test them on a car battery in various parallel configurations. Then maybe you can repurpose the 5A fuses to protect 00 wire...😛
Thank you very much, I have same that unbranded fuse and I tested them my self... man they are unblown able ☠️☠️
In the UK, I have found those "cheap and nasty" fuses have blades made of aluminum 0.5mm thick. The decent fuses have blades made of nickel plated brass, 0.7mm thick. So there is potential for the cheap fuses to give a bad contact. I once made sure I gave eveyone in my car club a "free fuse" and told them that if you can easily bend the blades like you can on your free gift, don't buy it...
yes, my experience Aluminum is soft and forms a high resistant connection over time. Dito throw away the non-branded fuses.
Brass is a pretty dismal conductor of heat, whereas aluminum is as good as it gets, excluding copper and silver. Since fuses are really just self-heating resistors that melt themselves to oblivion, removing heat "too fast" will delay or even prevent blowing.
@@raymiller5738
That's why aluminum has been largely banned for AC mains wiring - joints tended to be unreliable and cause fires. There are problems with both oxidation (aluminum oxide is an excellent insulator) and "cold flow."
I have a small single-AA cell, single mode flashlight I really like except for one problem - the tail cap of case was notorious for going high-resistance between the cap and body threads. A tiny bit of a zinc paste (Gardner Bender OX-100B), intended for use on aluminum wires, on the threads fixed the problem nicely.
Excellent video, thanx for the warning. I did buy a non-branded kit "ABN". Tested the kit on my PSU and the fuses up to 20A cleared in a timely manner. Looks like the fuses you had were just bits of wire between the lugs... Thanks again.
I discovered this a while ago, After having to re wire the loom on a friends Quadbike, I tested the 45A at 60A and it melted the plastic but didn't blow. Lawson Fuses are the best.
I was scrapping a Fiat and cut a wire of the fuel injection on accident.
The fuse of the fuel injection melted it's casing and later the entire socket but did not blow . The wires started burning first. It was an original fuse
Nice video. And also a very important topic. These cheap "dummy-fuses" won#t save you a penny, if your car or even your house catches fire and burns to ashes. But, just for showing the seriousness of the danger (and for fun), you should have used thinner wire, that actually melts or lights up.
Anyway, amazing video, thank you. 73s
I had that cheap chinese fuse kit. After seeing your video 2 months ago i threw them all out and bought all Bussman. I did use the chinese plastic case.
I still have my cheap Chinese/noname fuses, but only for doing more tests or videos. Not using them in any of my active equipment.
I have some no name fuses and no longer use them. One was melting, turning black, smoking, and almost caught fire after running at capacity for a long period of time.
There was a massive recall of these fuses a few years ago, because the only difference between the fuses was the colour of the body, as they all used the same stamped out fuse element, and simply put a different colour body on the top. Millions of boxes recalled, they had to go somewhere, so likely got sold off as lots cheap. Basically look at the elements, if they are all the same size they are all 30A fuses.
Thank you for sharing your testing, something I had not been considering a potential issue. I will examine and replace all my fuses now as well.
Great video. It is pretty scary that they are allowed to sell such a bad product that is supposed to provide safety. I am tossing all of my no name fuses out immediately.
Thanks I'm changing my fuses today!
Thanks for the chart, one more data point, typically those chinese fuses are aluminum, and aluminum on standard tinned brass terminals is a corrosion and fire hazard when exposed to wet environments. I had a piece of outdoor equipment, 30a fuse for the glow plugs ended up burning up the whole fuse block. clipping one fuse leg will show if its tinned brass or aluminum. Buss fuses are a guarantee to be tinned brass
Thanks for the tests. Just 2 comments, it could be sped up only, mentioned twice sloowly the ebay amazon (we got it the first time around! ;)). Second thing the mic scratching can be painful after a while. I hope it will help make your next viseo even better!
Thank you for this video! I had cheap fuses laying around and tested them, this is what i found:
1. 3A fuses did not blow at 10 amps even after 3 minutes
2. My switching-mode power supply blew a couple of 2A fuses at
Thank you for your excellent review. I also purchase a box of 300 no name blade fuses from EBay for $16 and had quite a different experience. I replace the original 30 Amp fuse with one from 30 Amp fuse from EBay that is in line with a solar regulator. The solar regulator runs a maximum of 25 amps and the plastic that encapsulated the blade fuse wire melted exposing the fuse wire. It seems that they made of a plastic with a very low melting point. I wonder if the current did get to 30 Amps or above 30 Amps that it would catch on fire.
Wow, so dangerous thanks for the video glad I only have standard height mini fuses that are no name. And my low profile ones are Bussman. Will be getting new fuses for digging into my families vehicles for the nonpainted no brand fuses
Great knowledge. I` m going to check all my DC fuses in our RV.
Had always assumed a fuse was a fuse, and even though I have a couple kits of brand-name fuses, I also have probably that exact same kit of generic fuses. Throwing it out. Thanks!
A very good demonstration and an eye-opener to modern day equipment. I have very little new equipment as I am a homebrewer and operate boat-anchor vacuum tube equipment. The fact that the voltage on the power supply drops to 0.6 volts and still maintains 20A is amazing to me. That is 12 watts of heat being dissipated in the fuse, as your temperature measurements indicated, which seems like it would melt the fuse link in a reasonably short time. Apparently not...
My power supplies are all the linear brute-force type and shorting one of them will likely not drop the voltage any significant amount so we would end up with the full 15 volts (as in your example) at 20A for 300 watts being dissipated in the fuse and we all know where that is going to go and hopefully the fuse will protect the equipment from catastrophic damage and possible fire.
With over-current sensing in SMPS in modern equipment, it almost seems redundant to put a fuse in the output side, although I think it is still a good idea. 73 WA4QGA
I was reminded long long long ago that my auto instructor said you're paying for the metal they use for these fuses, & they were coming from a place of experience.
I was concerned about this exact issue, so I didn't get one from amazon. Thanks for confirming my concern.
My no name fuses from Amazon have worked fine for years.
I tested them prior to installing and they opened at the proper amp.
This comes as no surprise to me, Chinese manufacturering often times substitutes for materials that are not in stock or considered too costly in their opinion. They probably substituted aluminum wire for the tin or indium fuse element. One clue is the DC resistance, it is most likely abnormally low.
I discovered similar problems with the Chinese marine style thermal circuit breakers 3 years ago. These trip at 1/3rd to 1/10th the stated current. They can also chatter when they are about to trip. I finally had to test each breaker for it's trip point, then label the breakers accordingly.
I remember a 528e back when German cars use ceramic/thermosetting strip fuses . Red 16 white 8blue25. It was burned out in the roof from a dome light short. The fuse was replaced from white to blue.
I got a bag of fifty 3A ATC fuses. I'm good to go for all my needs. I've been testing DC disconnect breakers. A 10A won't even trip at 22A.
I have considered doing a video about breakers. Even good quality circuit breakers take longer to trip than a fuse because of the nature of how they operate. As I said at the beginning of the video, fuses and circuit breakers are primarily designed to protect wiring from catching fire. They’re not really designed to protect our electronic equipment from internal faults.
@@HamRadioA2Z You might also want to look at DC breakers. Some of the polarized ones actually interrupt the arc faster when connected in reverse. I get all this stuff free from manufacturers. Sure glad I'm not having top for some of these products. It is the wild west on these CE listed products!
Interesting I had problems with no name fuses but the other way around five amp fuses kept blowing on a constant current battery charger putting out four amps did not blow instantly but after about three charges of the battery on a mobility scooter.
I'll second this. Most of the Harbor Freight or any unbranded fuses always tended to pop for no reason under normal load.
I'm not sure using a fuse as a shorting element across the terminals of a power supply is an accurate test. I think the better test would be to place the fuse mid circuit against a controlled, resistive load through a larger power source.
From experience over many years we often found that any fuse, regardless of the rating is better than no fuse. That meaning that even a 20a fuse will protect a circuit rated at 10a better than a solid wire, bolt, or tin foil wrapped old fuse. In most cases the fuse will blow before the wire melts. This does not apply if your trying to protect fine circuitry though.
A case that comes to mind was a vehicle which had its battery polarity swapped by a careless tow truck driver. The car was brand new but the woman had left a power inverter on charging her laptop all day while at the mall.
The end result was fairly substantial damage, the alternator, ECM, radio, air bag monitor, and just about every circuit that had any sort of constant memory function was burned out. The radio failed so thoroughly that even the LCD display was melted inside. Not a single fuse had blown in either fuse panel. Out of curiosity I kept and opened most of the damaged components to see exactly how and what failed.
The radio, ECM, and alternator took the most damage. In the alternator all but one diode was burnt, and the voltage regulator was an open circuit across all terminals and it had even burned through the plastic cover on the back. The radio was pretty much a total loss, no one component failed and parts of each circuit each showed major burning damage. In the ECM, the failure point was at the case ground, which on that model was a 3/16 inch tab of steel which overlapped the main board as a ground, the corner of the board and the tab were melted and open, as was the memory portion of the circuit board nearest to the constant power pin.
The explanation I got from the tow truck driver was that his jumper cable quick disconnect was broken apart and he had stuck the wires in by hand and 'got it wrong I guess'. He said he knew something was off when he smelled smoke and realized that the battery terminal had melted. All of the fuses were OEM factory fuses the car was only a few weeks old at the time.
At the time I would have figured that at least some of the fuses of fuse links would have blown long before that sort of damage occurred. I went so far as to call both the manufacturer and their engineering department to try and get an answer. What I finally was told by an engineer was that even though a fuse may see current in excess of its rating, when put into a direct short situation like that often the fuse element will liquefy vs. just blow and clear. In other words, even molten metal can conduct electricity just fine. In such a case, the fuse would not clear until the surrounding plastic was compromised or melted through. Since most fuses are made from acrylic, that can take longer than it would take for most circuit board traces to melt.
Back when I was dealing with that case I pushed the issue with several engineers if no reason than my own curiosity. I went so far as to ship them all the damaged components directly to get a real answer, and the end result was the statement that fuses are not meant to protect from a dead short of reverse of current, they're there to prevent 'over current' or excessive amp draw. They also explained that wiring itself, if large enough can 'absorb' so to speak a great deal of current under sudden load both due to natural resistance and distance. An example of this is to look at how much current is lost over a very long run of wire if the wire is too small.
Also, applying a dead short to a fuse with a 'regulated' power supply also may not be truly creating the high current short you would expect. The regulator circuit itself may well be taking up some of the load or preventing full current from affecting the fuse or short.
A good test would be to use a large variable resistor with the fuse inline on the positive side of the circuit.
At 20 amps of true current, even a solid copper wire will melt and get hot enough to burn wood or melt its insulation at far less current. I think if that power supply was actually applying 20 amps of current to that fuse, its plastic housing would have melted even if the fuse failed to blow.
Blade fuses are also notorious for being inaccurate or fairly random and are rarely used in better components, they're just easy to install and test and less likely to be wrapped in aluminum foil when they blow like a glass fuse often is. They also withstand shock and corrosion better than a glass fuse. A good example is that you never see blade type fuses on stereo equipment or speakers, or on higher voltage applications.
I think a more accurate test of a fuse like this would be to put the fuse in circuit between a resistive load and a larger power supply, or battery. Control the voltage through a VR circuit, and the amperage through a variable resistor with a meter.
Then ramp up the current and record the point when the fuse blows. Chances are it'll
clear within 10 percent of its rating every time.
Think of it another way, if you take a fresh 9v battery and short it out with a small paperclip, and measure the temperature. It'll get far hotter than 150°F. It may even glow red. Do so with a larger battery and it'll burn through. So to think that any 5 amp fuse, made from aluminum, brass, lead, or tin, taking a true 20 amps without smoke or melted plastic isn't likely
@@VB-bk1lh The other thing about using a regulated power supply is to regulate the amps the voltage is dropped so that fuse was only taking 20 watts and not three hundred watts which is what you would have at full 15 voltas 20 amps and its total power that does the heating and therefore melts the fuse, a wattage rating would ne more realistic.
@VB-bk1lh it doesn't matter if its directly across a power supply or in a circuit with a load. 20A is 20A it makes no difference. The 5A should have blown in a few 1/10 of a second.
Very good illustration.
I look forward to seeing the crowbar device. I’ve always been mystified that little premade in-line crowbar devices aren’t on the market. I’d love to see some adjustable ones that could be used on 13.8 or even 5v applications.
I tend to tinker with power supplies and have modified some to have remote sensing, but I’m always worried that something will go wrong and the devices being powered could see high voltages if the sensing wire ever became disconnected.
If the supply lines are big enough to handle the current, there isn't any need for sense lines, unless you have some very fussy equipment, but even then, increase the diameter of the supply lines to meet the demand without excess Voltage drop.
A crowbar design is quite old-fashioned. There are modern power switch solutions that are faster, more reliable and optionally auto-resetting.
Well shit, I just got a whole bunch of cheap Amazon fuses. I've got a scope and PSU, I'm gonna set up the same test you did and see if they are junk. Thanks for posting!
I pushed 4.2 amps through a 2 amp fuse for a couple mins. I'll need to build a way to do higher amp tests. But I'm gonna try to return this crap to Amazon.
Now I also have to rip my motorcycle apart to pull out the fuse I put in.
@@rjmackenzieDude, you need to go and read about fuses and their characteristics to understand why a 2amp fuse could easily pass 4 amps. The idea that a 2amp fuse ought to blow after 2amps is nonsense. A fuse can withstand many times its rating before it blows.
It seems like the manufacturer's testing methodology involved either dry labs or shorting mains.
This topic was covered a year or more ago, with comparison tests as well. ALL the colors of blade fuses from parts unknown would hold 40 AMPS ... be they molded as a 5, 10, 20, 30 OR 40. A USED CAR LIKELY HAS SOME OF THESE. The hazard is from putting in a no-blo fuse into a bad circuit that popped the GOOD ( blown ) fuse, without diagnosing and repairing the vehicle. Expect to ruin a wire harness or worse.
Very revealing! Thank you! And to think some amateur airplane builders might use these cheap bad fuses as their circuit breakers!!
I had some of these fuses around and used them once for some relays, a fan they were controlling got jammed and it should have blown the fuse but instead melted all the plastic off of the fuse and got everything pretty hot. I bought a box of legitimate brand fuses and made sure that I never used the cheap ones again.
I see you using a IR thermometer. Have you considered purchasing a thermal imager? I highly recommend the UNI-T UTI260B. In my opinion it's the best value for the quality you get. I bought mine a few weeks ago for $280 USD and you can get a macro lens for circuit board close-ups. Northridge fix has a review of the exact model
also, I replicated your results and couldn't blow my 2 amp no name fuse at 20 amps. The plastic melted but the metal did not open. Thanks for the warning
Outstanding video and demonstration. Thanks for sharing this. 73’s N2STX
Wow! You're right, thanks for testing these. I have a box of no name fuses also, I just tested several 5 amp fuses on a quality 20 amp power supply - they didn't blow, I even tested the ten amp fuses.
Great subject, Thank you, I had suspected this, you proved it. Thanks from N8AGW
I have my fuses from Ali or from al local store which is called "Schraube" it means screw. I will test them tomorrow. Very important video
Thank you so much !!! You are seriously saving things and people with this.
I have also noticed that the blades seem to be thinner and have bad contact with some fuse holders.
Afterwards Happy 4th of July, Tom. Good to see you back again.. 73 de Uncle Günter 💯👌🙋♂
Excellent and informative video! Time to double check my fuses!! Subscribed!!
Thanks for doing this experiment! Would you repeat it without that bench power supply, and use a car battery instead?
The current and voltage at the fuse under test could be measured with a two channel oscilloscope (one channel connected to a suitable current shunt) 73, de K7GVG
And add a contactor rated a few hundred amps, so it can be done out in the yard/driveway and switched on or off from a safe distance in case the wires blow first.
I tested the set that I have, and the fuses are operating correctly. They blow in 1s at 2x rated current. The only slight issue that I don't know if it's normal or not, at 1.3x current they glow red and melt the plastic a bit but they do eventually blow. The set is Herbert Müllner BOX-AS147. They are visually similar to yours with the embossed current rating that's hard to read but have a different fusing element. So it's not possible to distinguish good from bad just visually.
Thanks for sharing this. I always say that government has a function. One of those functions is to protect consumers.
When safety devices fail to do their job, the government should prohibit their sale as a risk to safety.
My only concern with your test is you showed only one test of a 5 amp fuse. I'd like to see the results of 5-5 amp, 5-10 amp, and 5 -15 amp fuses.
Certifications are important. But even without them any safety device should perform as expected or be prohibited from sale.
I did try several of the 5’s with similar results. Stay tuned for a follow up video.
Yeah, well, it seems the government is about as effective as these fuses, but we don't get a bargain price for them!
Do you think the issue with the 5 amp fuse not blowing, may have be due low voltage used in the test. 0.6 volts (0.6 volts x 21 amps = 12.6 watts). Did you try the same fuse at 13.8 volts (13.8 volts x 21 amps = 289.9 watts).
You need to review how ohms law works and how a constant current power supply works.
@@stargazer7644 exactly, the voltage across is irrelevant, as the psu output volts will rise to whatever the fuse and cables will allow to appear across it with that current flowing,, its the current thats important
As an update from my last post, I checked the rating of the ATC fuses and they are rated at 32 volts DC for each specific current rating. It is logical to also test the fuse at the rated voltage. There is nothing to do with it being a constant current power supply, if the fuses at not being tested at their rated voltage. 🙂
@@petergravy6893 You aren't getting it. You CANNOT test fuses both at their rated voltage AND their rated current at the same time. That's not how Ohm's Law works. The voltage across a shorted fuse is dictated entirely by the resistance of the fuse and the internal resistance of your power supply. Regardless, voltage isn't what opens a fuse, current is what opens a fuse. The only reason a fuse even has a voltage rating is because they can arc over after they've opened if you have too much voltage across them.
You can test them at their rated voltage with a constant voltage power supply but then the current will be enormous. Or, you can test them at their rated current with a constant current power supply and the voltage will be small. This is how physics works, so yes, it has everything to do with if you're using a constant current power supply. If you don't even understand the most basic principle in electronics (Ohm's law), then you really don't have any idea what you're talking about.
@@petergravy6893 it doesnt matter, its the current that does the heating, the fuse is very low resistance, less than an ohm, it will only need a couple of volts at most to force a high current through it,
I've been seeing some strange failure modes with older H-type ribbon Buss glass fuses. The fuse blows in the center, deposition coats the glass, and the remaining ribbon ends sag and reestablish a resistive contact. The circuit looks like the right voltage is there, but can carry no major current. Twice in 2 years.
Great video.. I was just mentioning to my brother a few days ago not to buy no-name fuses and to stick bussmann, etc. For individual fuses, I usually purchase them from digikey or mouser to be safe.
Totally agree. Unfortunately it's really hard in the UK to find any parts like this that aren't cheap C...ese crap. Britain used to make all these kinds of things, but all those companies have long since closed down. I searched for ages and still couldn't find any quality fuses.
even 'top brand' stuff is often made in china, so much is, but made to the brands specifications by some third party manufacturer
If I remember correctly there was a huge bruhaha several years ago about these Chineseium fuses not working properly and were extremely dangerous.
Chineseium ... did you learn that in racist school? 😘
@@michaelseitz8938 I learned it over the years because Chinese manufactures often play fast and loose with specifications. SSRs that don't work at rated input control voltage, USB automotive power adapters that do not deliver rated current and become dangerously hot, multichip LED modules that are not well balanced and become intermittent due to bond wire problems. Just to name a few off the top of my head.
I actually ran into this myself doing load testing for sizing the fuse for an electronics project - I use pico fuses which are about the size of a grain of rice. The Amazon ones listed for 500mA fast blow didn't blow until over 1.5A. Some knock-off Littelfuse ones I found on there too, rated for 2A Fast Blow, didn't blow until they had almost 250% over their rating (4.5A), and that was ratcheting up the current quickly. I got on Digikey and got genuine Littlefuse pico fuses, and they all blow at almost EXACTLY their specified current. It's almost like these Chinese companies just stamp out fuses from any pot metal they can find and then injection mold it. It's truly scary if you think about it.