Are block heaters a fire hazard?

Paladin · December 28, 2007, 10:55:51 AM

The last time I started the beast it was nearly as cold as it is now. I plugged in the block heater for a few hours and then went out to start it and it came right to life.
I was going to plug the heater in over night so as to have it all ready when I needed it the next morning when I want to move it around but I was worried about fire danger. We've lost a number of homes in the last week around here to fires, usually space heater related. I'd hate to be on the news for burning my bus and house down due to a block heater.

oldmansax · December 28, 2007, 11:09:18 AM

I have personally never heard of a block heater causing a fire. If the cord was frayed otherwise damaged, that could cause a problem but it is also easily checked.

TOM

Len Silva · December 28, 2007, 11:10:03 AM

I think there is zero risk of a fire from the heater itself. That does not include the risk from defective wiring, the same as any other electrical device. If the block heater is not submersed in coolant, it will burn itself out, but still minimal risk of a fire.

Len

gumpy · December 28, 2007, 12:15:11 PM

Agreed. The only risk is in a defective cord. Check it to make sure it's not cracked, corroded, or otherwise faulty. Even then, it should be plugged into a protected circuit in the house, and if shorted, should trip the breaker or GFCI. Make sure you use a properly sized extension cord. 12ga or larger is recommended.

The heater element is not a hazard, as it's immersed in liquid.

TomC · December 28, 2007, 02:45:13 PM

When I was driving truck, I had a 6.5 Onan commerial gas (2cylinder opposed Emerald) for my generator for my sleeper. Whenever the gen was on no matter the weather, the block heater was also on to create a constant 1500 watt load on the gen. As consequence, my first gen lasted just over 12,000 hours without overhaul. The electric block heater is just a heating coil that should not cause a fire. There is always a chance with 1500 watts going through a cord. Just check the heating of the cord and connections for overheating and you shouldn't ever have a problem. Good Luck, TomC

donnreeves · December 29, 2007, 04:44:42 AM

I have a friend with a totally burned up Kenworth dump caused by the block heater. The connecting pins from the cord to the heater corode over time causeing resistance that heats up the cord. With a faulty breaker it can and does cause fires. I have had personal experiance with a cord burning, but fortunatly my breaker tripped. Donn

Paso One · December 29, 2007, 06:09:32 AM

Hi Paladin

I wouldn't worry about leaving your bus plugged in for fear of fire. (heck you could be struck by lightning)

In the frozen north many vehicles are left plugged in 24 hours a day. Other than the fact it is wasting energy it does not pose a real fire threat.

Our snow clearing equipment with a 750 watt or 1500 watt circulating heaters left plugged in are so toasty when started, you have almost instant cab heat.

Moof · January 02, 2008, 08:21:59 AM

I have investigated numerous fires where the ignition source was the block heater (battery blanket, etc..) Now that is just the ignition source, you still need fuel. Generally the fuel in these types of fire is years of caked on grease and crud. The best way to reduce your chance of a fire is to keep you engine clean (good idea anyway) and check your block heater (and associated wiring) every year before you use it.

It is also recommended to park your vehicle at least 15 feet from any structure while it is plugged in. Things do happen and there is no sense burning your house or garage down just because you had a vehicle fire.

Keep it safe!!!

jackhartjr · January 02, 2008, 08:31:21 AM

Donnreeves, you said; "I have a friend with a totally burned up Kenworth dump caused by the block heater. The connecting pins from the cord to the heater corode over time causeing resistance that heats up the cord. With a faulty breaker it can and does cause fires. I have had personal experiance with a cord burning, but fortunatly my breaker tripped. Donn "

Note the faulty breaker was the primary culprit here. Plus, I can surmise that the cord was old?

Good post here!
Thanks
Jack

ChuckMC9 · January 02, 2008, 09:07:25 AM

Quote from: Moof on January 02, 2008, 08:21:59 AM
It is also recommended to park your vehicle at least 15 feet from any structure while it is plugged in.

But, but ... the vehicle IS the structure!!! Duh!

LOL

kyle4501 · January 02, 2008, 09:23:52 AM

I left my bus block heaters plugged in for 3 weeks straight (It has 2) because I didn't have time to change the coolant. When the power bill arrived, I made time to change the coolant! (As soon as the shock wore off)

3000 watts x 24 hours x 21 days = more than the antifreeze cost.

(well, almost)

My points are-
1 - if the heaters & cords are in good condition, they are safe for continuous use.
2 - block heaters don't cycle on & off like space heaters (mine didn't), so you may want to just plug her in a couple of hours before you want to start to save some $$

Don4107 · January 02, 2008, 10:24:28 AM

"Note the faulty breaker was the primary culprit here. Plus, I can surmise that the cord was old?"

You don't need a bad breaker for a block heater, or for that matter any high draw device, to cause a fire. A high resistance connection can generate enough heat to set the cord/oil/grease/other fuel source on fire without ever shorting out the cord. I have changed a couple cords, one of which was turning to charcoal, and one heater because of the heat damage by the bad connections. Once the fire gets going it is quite likely the cord will melt and short and (hopefully) trip the breaker. Not to say that a shorted cord and a bad breaker can't, it is just not the only cause.

Don 4107