Stan Adams Posted August 26, 2023 Share Posted August 26, 2023 One of the many reasons I despise cheap Chinese plastic fans. A week ago Monday, my neighbor’s garage burned down. If I had not kept water on mine, it would have too 25’ away. Investigators determined the cause was a plastic oscillating fan. I asked why the thermal fuse did not protect it. The one investigator said he could not count how many fires he has seen caused by cheap Chinese fans. The moment he found the rotor, he said here is the culprit. Notice the plastic melted around the shaft between the rotor & bearing. 3 Quote Link to comment Share on other sites More sharing options...
Arjun Saini Posted August 26, 2023 Share Posted August 26, 2023 That’s why I keep an Emerson going in my garage! Chinese junk stinks Quote Link to comment Share on other sites More sharing options...
Terry Plata Posted August 26, 2023 Share Posted August 26, 2023 Stan, do you have any more details? I wonder if the fan caused the fire or was just burned up in the fire? Do these small fan motors have a thermal breaker like the larger motors? Quote Link to comment Share on other sites More sharing options...
James Landry Posted August 26, 2023 Share Posted August 26, 2023 EGAD! Last year my sister had a cheap fan in her bedroom that was running really slow and asked me to "fix it". It ran on the bench for a short time before it got super hot and blew the mini fuse in the cord. I took it apart 3× only to find there was no fixing to it and tossed it. Quote Link to comment Share on other sites More sharing options...
Chris Jacobsen Posted August 26, 2023 Share Posted August 26, 2023 I also will agree on the uber crappiness of China fans, primary weak point is the grease. In a couple of my parents fans hardened or thickened causing a lot of resistance. I redid them by soaking out the grease in gasoline and putting in synthetic axle grease. I had one metal fan have all the spot welds on the cage pop one by one till it fell onto the blades. I also had bad experiences with teflon grease, I have no love for that either. On the bright side, my parents love the huge, powerful 50s Vornado, a Hu ter D10 and the Hunter C16 I gave them. They put the China fans to shame by overwhelming performance and lasting for decades (the D10). Quote Link to comment Share on other sites More sharing options...
David Allen Posted August 26, 2023 Share Posted August 26, 2023 This is unsurprising and very sad. These small motors are supposed to have a thermal fuse which will open and stop the current permanently if the motor overheats. It's supposed to break the circuit at a temperature below that which causes the winding to short circuit and fully burn out. It is widely known that these thermal fuses are unreliable. Most better brands will have a thermal fuse, as well as a "traditional" overcurrent fuse. The overcurrent fuse will blow after the winding has started to burn out and short out, but should be a backup to break the circuit before actual ignition occurs. The problem with thermal fuses is complex. They use an alloy which is blended to melt at a certain temperature. It seems that if the thermal fuse is repeatedly cycled through heat / cool cycles, it can become less reliable. This happens when each hot cycle reaches near its failure point but doesn't actually blow the fuse. After enough thermal cycles something happens to the alloy and it will not perform as intended. This is such a problem in toilet ventilation fans that a forensic engineering report has been done. They go in depth and even have x-ray images of thermal fuses which have blown, and which have not blown in spite of the motor catching fire. Link at bottom of this post. The safest approach is layers of defense. In the case of a stalled motor, a certain current will flow. We call this locked-rotor current. Motors will typically have a mechanism to survive locked rotor events, such as an automatic reset overload protector, or "impedance protection" where the design of the motor results in a very minimal locked-rotor current which won't in and of its self burn the motor out. The thermal fuse should be chosen to prevent initial thermal damage to the winding. In other words it should stop the current going to a stalled motor (based on temperature) before any sort of smoke or insulation breakdown happens. If this happens, replacement of the thermal use could return the motor to service. If the thermal fuse fails to open, the motor will reach a thermal damage point and will start to smoke and suffer winding insulation failure. As the winding insulation fails and turn-to-turn shorts appear, there will be a rising current draw, which exceeds the normal locked-rotor current. This will climb rapidly as more winding turns short. This is where the overcurrent fuse comes into play. It will be a secondary safety device to prevent a fire but it will only blow after the motor has suffered severe damage. Without this fuse, the end result will be 10's of amps and an eventual burning through of the winding wire. This creates an arc and starts a fire. If there are combustible materials around the motor this small flame up can ignite a major fire. If you are considering adding an overcurrent fuse to a fan that is a great idea. Typically, for small motors like tabletop fans or box fans, one would want to select a time-delay overcurrent fuse and size the fuse for about 125% of normal running current. Sincerely, David https://www.cpsc.gov/s3fs-public/Eutectic-TCO-Report-6b6-cleared-cleaned-January-2018-version.pdf 2 Quote Link to comment Share on other sites More sharing options...
Jim Kovar Posted August 26, 2023 Share Posted August 26, 2023 46 minutes ago, David Allen said: https://www.cpsc.gov/s3fs-public/Eutectic-TCO-Report-6b6-cleared-cleaned-January-2018-version.pdf Thanks, David. Anything more,... er,... current? Quote Link to comment Share on other sites More sharing options...
Stan Adams Posted August 26, 2023 Author Share Posted August 26, 2023 David, that is exactly what the investigator said when I asked why the thermal fuse didn’t blow. 👍 1 Quote Link to comment Share on other sites More sharing options...
David Allen Posted August 27, 2023 Share Posted August 27, 2023 21 hours ago, Jim Kovar said: Thanks, David. Anything more,... er,... current? Jim, nothing has changed and the facts uncovered in 2017 still apply. Quote Link to comment Share on other sites More sharing options...
Stan Adams Posted August 27, 2023 Author Share Posted August 27, 2023 On 8/25/2023 at 10:04 PM, Terry Plata said: Stan, do you have any more details? I wonder if the fan caused the fire or was just burned up in the fire? Do these small fan motors have a thermal breaker like the larger motors? Terry, the investigator ruled the fan started the fire. The thermal fuse did not blow because of the reasons David Allen mentioned. Investigator said this sure isn't uncommon. Quote Link to comment Share on other sites More sharing options...
Andrew Block Posted August 28, 2023 Share Posted August 28, 2023 Do we have any idea what brand or type of fan it was? I am curious… Quote Link to comment Share on other sites More sharing options...
Tom Zapf Posted August 28, 2023 Share Posted August 28, 2023 ITS VERY INTERESTING THIS CAME UP NOW. I HAD POSTED THAT I HAD A LASKO 16" THAT HAD STOPPED AND THE THERMAL FUSE BLEW. WE HAD A "MOTOR DAY" AND THE LINK WAS REMOVED AND THE FAN WORKS. IT IS ONLY USED OUTSIDE ON THE PATIO. I POSTED WHERE YOU FIND THE DARN THINGS AND OTHERS ALSO SAID LET US KNOW IF YOU FIND ANY. I ADDED A FUSED LINE CORD , BUT STILL THE FAN IS ONLY FOR OUTSIDE ON THE PATIO, NOT IN THE GARAGE OR HOUSE . I FOUND THERMAL FUSES ON EBAY AT 2 AMP NOT THE 2.5 ON THE ONE I HAD BLOWN AND AM GOING TO TRY IT . I THINK ANOTHER MAJOR ISSUE IS IN THE "OLD DAYS" A FAN OVERHEAT IN A METAL HOUSING DID NOT RESULT IN THE ACTUALY FAN MOTOR COVER AND BODY CATCHING ON FIRE LIKE THE PLASTIC FANS NOW. THE WHOLE DARN THING BURNS UP, BASE COVER BLADE ETC ...VERY SCARY Quote Link to comment Share on other sites More sharing options...
Tom Zapf Posted August 28, 2023 Share Posted August 28, 2023 THE OTHER THING...I NEVER LEAVE FANS AND APPLIANCES RUNNING IF I AM NOT IN THE HOUSE OR YARD. IF I GO EVEN TO THE NEIGHBORS, EVERYTHING IS TURNED OFF...PERIOD...PLUS I USE THE LINE CORD AND UNPLUG THEM TO TURN OFF. ITS LESS WEAR AND TEAR ON OUR OLD SWTICHES BUT ALSO HELPS IF THERE IS A WORN CORD OR WIRING ISSUE...JUST MY 2 CENTS...I LEAVE NOTHING RUNNING OUT OF MY NEARBY SIGHT LINE Quote Link to comment Share on other sites More sharing options...
Paul Carmody Posted August 28, 2023 Share Posted August 28, 2023 It’s a wonder there is no class action lawsuit. Quote Link to comment Share on other sites More sharing options...
Andrew Block Posted August 28, 2023 Share Posted August 28, 2023 https://www.youtube.com/watch?v=Ucv8iVLzx3A&ab_channel=NITEofficial Quote Link to comment Share on other sites More sharing options...
James Landry Posted August 28, 2023 Share Posted August 28, 2023 3 hours ago, Paul Carmody said: It’s a wonder there is no class action lawsuit. I once got a settlement from a class action lawsuit! I received a 47 cent check in the mail!!! That baby got framed and hung on the wall for many years!!! 1 Quote Link to comment Share on other sites More sharing options...
Tom Zapf Posted August 29, 2023 Share Posted August 29, 2023 THAT FAN IN THE VIDEO IS A 1970'S VERSION IMAGINE HOW MUCH CHEAPER FANS ARE NOW..... THE PLASTIC EVERYTHING BURNS... WE USE FANS FROM THE 1920S AND YOU WONDER HOW MANY BULLETS WE DODGED . I HAD A FAN MOTOR RECENTLY GO AND POPPING SPITTING WHILE IT WAS ON THE SEIDEWALK OUTSIDE ...HMMMMMMM Quote Link to comment Share on other sites More sharing options...
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