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[on:]

I recently took apart a fan for someone who wanted me to fix it. It was UL listed according to the label on the back. However, I took it apart and I discovered that the motor is NOT protected against over load in any way, shape or form. A motor that has gummed up lubrication or failing bearings can eventually seize and this causes the motor to be "stalled" i.e. attempting to run but not able to turn. A stalled motor usually draws excessive current (but not enough to blow a 15 amp fuse in the electrical panel!) and this can overheat the windings, which damages the motor, and at higher voltages (such as from the wall socket) this could cause a fire!

Now, I'm fairly certain that since a stalled motor draws more power than a normal one, a properly sized slow-blow fuse would blow before a catastrophic failure occurred, right? Sure, it could blow due to a temporary condition such as a kid sticking something in it, but I'd rather put in a new fuse (or even get a new fan) than have my house burn down because I failed to periodically lubricate a <$20 fan! A thermostat mounted to the (usually metal) case of the motor would also work, though that might be more expensive than a fuse.

The scary thing is that the fan claims to be UL listed! How is that even possible? I thought UL was a SAFETY certification! How can an appliance with an unfused, non-overheat-protected 110v motor possibly meet any kind of safety standard??? Seriously, I'd hate to see an appliance that ISN'T UL listed! Does UL no longer even so much as look inside the appliance before approving it? How bad would it have to be to NOT be listed?

Besides, what bean-counter decided that they would rather face a wrongful death lawsuit due to a fire than raise the cost of the product by a measly 25 cents???

[Reply #1 on:]

Before indicting UL of missing something, maybe you need to verify if the product is actually UL certified.  Stickers and markings on a product are meaningless.

[Reply #2 on:]

How is that even possible? I thought UL was a SAFETY certification! How can an appliance with an unfused, non-overheat-protected 110v motor possibly meet any kind of safety standard?

I can assure you that UL will have tested it. It is not a UL requirement that everything has to have a fuse. I have put equipment through UL without a fuse.

There are many other ways of preventing fires other than a fuse.
Was it a UL mark or a RUL mark with the R backwards? If the latter then it was only a component, it is the whole system that gets the normal UL mark. An approved component by itself does not have to be safe only conform to certain standards.

[Reply #3 on:]

my house burn down

Maybe they determined that a stalled motor won't get hot?

http://xkcd.com/463/

[Reply #4 on:]

Are you sure there was no thermal fuse inside the motor? It would typically be a bimetallic fuse not much thicker than the wires themselves; not easy to spot unless you know what you're looking for.