How, Why, Solution

[Smoky14]

My neighbor's house just burned to the ground. The fire investigator says the fan motor in the freezer, located in the garage, overheated and set the unit on fire.
Would not, should not a circuit breaker or internal fuse have gone before the motor got hot enough to burst into flames.
Since I have motors in my garage which run unattended I'm concerned about a similar incident.
Any wisdom/suggestions from you guys would be appreciated. Having had one house burn to the ground, arson, I'm just a little paranoid about fire.
Thanks
Smoky

 

[Hokiefyd]

A circuit breaker provides over-current protection, such as if a piece of equipment experiences an electrical short circuit. To my knowledge, there is no way for a circuit breaker to protect against an electrical motor overheating...unless a short circuit is also involved somehow.

 

[IndyIan]

Clean your motors out once in a while would be the best bet. I imagine there probably was a few or a lot of cobwebs that helped things get going.
And make sure you have house insurance. I am amazed that people let that slip sometimes.

 

[Thermo1223]

Well an older motor can seize or stop turning for whatever reason, overheat but never trip for overcurrent.

Most new motors have overheat protection while older ones do not I believe.

IMO that was what most likely happened.

 

[Food Scientist]

I wonder if installing a GFCI plug would prevent this.

 

[AandPDan]

Originally Posted By: SVTCobra
I wonder if installing a GFCI plug would prevent this.


Nope. It only looks for current being equal on the hot/neutral. It won't protect against an overload either.

 

[OneEyeJack]

A couple of extra smoke detectors to warn you when you're at home. Maybe hook them up to the Internet so you get a phone call when they go off.

 

[440Magnum]

Very small motors (like a freezer or refrigerator fan) are actually one of the bigger fire risks in the home, IMO. Its part of an appliance that needs to draw a fair amount of current (for the compressor in this case), so the main breaker will *never* detect or protect against the tiny fan motor being locked up. In contrast, if the compressor on your central AC locks up, the breaker will trip in short order.

That said, built in thermal overheat protectors have been the norm on things like that for decades. Perhaps it was a replacement, or perhaps the thermal protector itself failed. Nothing is totally foolproof. Routine cleaning of the under-freezer condensor fan and motor is always a good idea, too.

 

[4wheeldog]

Also, don't store cardboard or other combustibles behind the freezer. Keep it a few inches from the wall, and clean behind it occasionally. Do not put shelves above the unit, either. Then, even if it burns, it will be confined to the freezer, not the whole d@mned garage.

 

[bullwinkle]

Originally Posted By: Smoky14
My neighbor's house just burned to the ground. The fire investigator says the fan motor in the freezer, located in the garage, overheated and set the unit on fire.
Would not, should not a circuit breaker or internal fuse have gone before the motor got hot enough to burst into flames.
Since I have motors in my garage which run unattended I'm concerned about a similar incident.
Any wisdom/suggestions from you guys would be appreciated. Having had one house burn to the ground, arson, I'm just a little paranoid about fire.
Thanks
Smoky
It's unusual, but not impossible-those fan motors have internal thermal overloads, but it could have even been the motor wiring that failed. An average 15 or 20 amp house circuit breaker wouldn't stop it.

 

[SteveSRT8]

Ouch. My heart goes out to that family. Few things worse than losing EVERYTHING.

The simple fact is that you can't remove all the risk, you can only minimize it. IMO the best fire protection is prevention, then a suite of fire and smoke detectors that are networked. Many these days will call your phone or send you an email...

 

[larry007]

A little off topic but recently took the top and front panel off the clothes dryer to address some squeaks. I was amazed at the lint buildup, motor cooling fins and duct built into the front panel filled my shop vac. May start cleaning this occasionally.

 

[Dave Sherman]

Sorry to hear that, and my sympathies for your neighbors. As others have said, circuit breakers only limit current. Things can still get overheated without tripping a circuit breaker.

I had a coffee maker thermostat fail on me once, and it started boiling the coffee before the thermal fuse opened. Circuit breaker wouldn't have helped if it had heated to the point of melting the plastic if it didn't have a thermal fuse built in.

Heck, I know somebody who had a DVR box go up in smoke, but fortunately he was there to unplug it before it got too far.

Even if appliances have fuses in them, it's still no guarantee that they can't fail in some way where they may be under their rated current, but something is dissipating more power than it should.

I even had something as mundane as a desk lamp with a plain jane 60 watt bulb fail in some way that the light bulb did not burn out the usual way. It was on a light timer, and one day I noticed it was not on. I saw that the plastic lamp shade had turned brown and partially melted, and the white light bulb had turned dark grey. Still scratching my head on how that one failed, but very glad it didn't get any further.

 

[sleddriver]

Any freezer/ refrig in a garage, down South in a hot, and particularly hot/humid climate, lives a very tough life. As if the environmental conditions (compared to indoors) aren't bad enough, there's also generally poor circulation, dirt, dust caught in years upon years of cobwebs to contend with. Spiders almost always build webs in areas where the air moves...near fans.

Many of these fans contain a thermal fuse designed to melt when the windings overheat. Evidently not your friends. Sorry to hear about their loss.....

I have several family members who have both reefers & freezers in the garage in hot/humid Gulf coast areas, where it's just nasty down on the slab....plus they complain about the electric bills!!

Gee...I wonder why?

 

[simple_gifts]

A friend's father worked for GE for a number of years. When I asked him about circuit breakers, he indicated a 20 amp CB could easily draw more than that in a residential box since they are really intended for dead shorts or current spikes. A incremental draw over the max didn't offer the protection most homeowners might believe.

This came up in a discussion about why when the woman upstairs ran a quartz heater on high with a number of other devices, the CB panel was extremely hot to the touch.

 

[Skid]

Most AC motors will fail due to bad bearings, and you'll hear them start to rattle long before the motor freezes up. So, you should have some advance notice.

It's a sad story, but I'm not worried about the fact pattern.

 

[Skid]

Uno mas. It occurs to me that the circuit breaker in a power strip will trigger much earlier than a circuit breaker in the panel. Wouldn't hurt to use on a continuously operating AC motor. I may do it myself, no reason not to.

 

[jrustles]

Really? A dinky little shaded pole motor can get so hot it ignites stuff!? It couldn't be an SP motor could it?

Agreed that a circuit breaker won't do anything. 100W is more than enough to light stuff on fire, it'll take a while, but possible.