Can Block Heater Cause Fire?

[jimainiac]

I just read a story in the paper about a garage fire with tractors inside. A couple of tractors were damaged, but one was a total loss. They said the block heater was plugged in on that one, and blamed the heater for starting the fire. Without knowing any more of the facts, I wonder how that could have happened? You would think a circuit breaker would trip first. Maybe a cord or plug problem. Hard to figure how the heater itself could cause a fire, being inside the block, immersed in the coolant. Got to be more to that story.

 

[DieselPower]

I would think the block heater cord was the culprit.

 

[shaley]

Gasser or diesel?

 

[jimainiac]

It's a working farm, I assume it was a diesel tractor.

 

[john_bud]

Well, they are designed to be pretty safe. BUT, there is about 600-1000w of power going into a big heating element. Let's just say that it could happen, but is thankfully a rare occurance.

Maybe if there was a lot of grease and oil dribbles and they were using a pan heater that wasn't making good contact. ?
jb

 

[LarryD]

Well I can confirm that a faulty block heater can produce some sparks.

I've got a 98 GMC and when I went to plug in the block heater last year there was a whole lot of fireworks where the cord connects to the unit. GFCI tripped immediately but coolant started to run all over the concrete.

There was no evidence of any kind of leaks prior to the incident so I can't say what happened. I can only imagine somehow there was some sort of short circuit between the hot and nuetral, besides the heater core.

 

[Taiser]

The cord on my wife's car block heater started smoldering and took a plastic headlight cover with it (plug was touching it). I doubt the actual heater would cause a problem, in our case the cord was frayed from wigling it back and forth all the time and the wires started shorting. Those cords get pretty stiff at -40 and then crack easy!!!!

 

[MadReferee]

Well, they are designed to be pretty safe. BUT, there is about 600-1000w of power going into a big heating element.

Standard block heaters are only 400 watts. At least for the Kubota parts as both the B and L series block heaters are 400 watts.

Problem could have been with the block heater cord, an extension cord that used the wrong gauge wire, or the heating element was not properly immersed in coolant. These warnings are all on the Kubota instruction sheet and I am sure they are on other manufacturer's sheets too.

 

[Atlas]

I'm sure there is much more to the story, but they aren't 'juicy details' worth reporting.

As far as the breaker not tripping before a fire started I don't find this out of the ordinary. Breakers and fuses are there to protect the circuit wire and components. If the circuit was protected at 20 amps but only 10 amps was required to start the fire (whatever the specific cause) the fuse or breaker won't/shouldn't blow or trip.