Bathroom Ceiling Fans

[mtnfireguy]

How many of you have had fires involving bathroom ceiling fans? If so, what caused the actual fire?

I have an electrician debating how a ceiling fan suspended in a housing could generate enough heat to cause a fire.

Thanks for any comments


[This message has been edited by mtnfireguy (edited 06-07-2001).]

[George Wendt, CFI]

We had one last year that took a house out. When the unit was installed, the wiring was not routed properly and was crimped under the case. The vibration wore through the insulation and caused it to short and ignite the insulation.

[Ahmed Khalfan]

I did, And The caused of fire very simple, if think in an old theory of the transparency of the energy …you will get my point ….in your case if the fan is jam the electrical energy will transpire to a heat… witch will barn the isolation of the transformer and the cable

[Richard]

I worked a convenience store fire that originated in a bathroom vent fan that the owner let run 24/7/365. Eventually the bearings on the fan locked up, causing the motor to overheat. Heat was conducted through the metal fan framework to wooden structural members, igniting them. Wiring to fan was equipped with a very large circuit breaker that failed to trip when the motor locked up and began to heat wiring up.

Store was totaled.

[Tcashel]

Fire in a bathroom ceiling fan. One event happened two yrs. ago involved a nail partially through a electrical wire into wood stud. Bathroom fan was not normally left on. However, resident had left fan on for some time ( they believe 3- days) The nail which had penetrated the insulation became energized whenever the fan was turned on. NO circuit breaker was activated as it did not detect a circuit fault. As far the breaker was concerned it was drawing power within it design limits.

A few fires involving fans and or light fixtures (high hat type) in which insulation materials wer in too close proximity to lamp housing. The listing on the fixtures required three inches of separation - basically heat could not dissapate.

[paulp]

Had one where I worked - a bath room fan mounted horizontally in a computer room to provide extra ventilation. Run 24 X 7 etc.
Bearings seized and plastic melted allowing the unit to drop onto the printer below.

[Steven C. Rowe]

I have invigatigated numerous fires involving bathroom ceiling fans. In addition I have discovered several problems. As mentioned in prior posts asside from pinched wiring creating shorts, The main thing I have experienced is a buildup of dust and lint on the fan motors. This is an accumulation built up over years of service. This condition insulates the motor and the heat generated by the motor running for a prolonged period of time that can not disipate, eventually leading to the ignition of the lint, plastic fan blade and into the structure. The majority of these fans use an impedance protected induction motor which limits the amount of amperage even in a locked rotor position, far below the amperage rating of the circuit breakers they are protected by. This allows for the device to continually heat. Testing I have done has varied from manufacturer and amount of dust and lint buildups. I was able to duplicate ignition on two different devices I tested after 7 hours and 11 hours of operation. One test was done under a locked rotor condition and the other was on a slow rotating fan with a very heavy accumulation of dust and lint. It was convincing enough for me to clean and lube all the bathroom ceing fans in my house.

Steven C. Rowe
Steven C. Rowe Fire Investigation
2817 New Smithville Road
Kutztown, PA 19530
Bus:610-285-6542
Fax:610-285-6543
e-mail scrfireinv@aol.com

[tomgranat]

To Steven Rowe.
I wish to clarify your statement: "The majority of these fans use an impedance protected induction motor which limits the amount of amperage even in a locked rotor position, far below the amperage rating of the circuit breakers they are protected by". The circuit breaker is sized to protect the wiring from the panel to the connected device. It is not rated to provide protection for the connected device unless it is a dedicated circuit. Even then, the breaker would be sized to pass the maximum amount of current the device requires under worse case conditions.

[TWalker]

Dust! Have encountered it on the job and at home. Fortunately, at home came to me as a check after my first encounter on the job. My first experience came in a restroom in a conveience store. Fan had locked up due to either buildup of dust, which was unbelievably thick, and or bearings. In either case, motor obviously heated up to the point of melting plastic decorative vent covering, napalming it down on the the toilet seat, setting it ablaze. Fan was original equiptment and had never been serviced in 12 years. I have had several encounters since and when I do safety talks, I encourage to check and clean fans every 6 months.