robert chilton

Yes the third prong is a ground. A ground is nothing more than an alternate neutral path if you follow it back far enough. The neutral and ground are bonded (tied) together at the electrical panel. Then at every power pole with an electrical device (switch, transformer, etc) or every second or third pole. The house hold ground is tied to the same style 8' copper rod driven into the ground outside your house as the power company uses on the electrical grid.
Electrically speaking a 750 watt heater only draws 6.25 Amps. That being said a 14 gauge cord will easly carry the current. 14 is the smallest wire allowed to be used in a household electrical circuit on a 15 amp breaker although many localities require wire no smaller than #12AWG wire. You would be perfectly safe running the the cord without the ground wire. The only purpose of the ground is to give the electricity a place to flow if a short were to occur in the hopes of avoiding a shock. I am sure that many people will say that you will have to have the ground but you really do not need it to operate the heater safely but it is a personal call.
You really shouldn't run electrical outlets off of a lighting circuit by NEC (National Electrical Code) code but it will work just fine. You should make sure that lighting circuit is not near its max capacity. Also check to see if the wire is aluminum. This was legal years ago but the strands of the wire break easily and will lower its ability to carry any amperage. Broken strands equal more resistance which equals heat. If only a few bulbs are on the circuit and it has copper wire running off of a 15 amp breaker you should be fine. If you really want to stress safety, the total electrical load on a 15 amp breaker shouldn't exceed 12 Amps. It may be helpful for ya to know watts/volts= amps. Therefore a 100 watt lightbulb draws 0.84 Amps.
As to the question about the #12 extention cord. That is more than adequite as long as the circuit (outlet along with other outlets tied to the same circuit breaker) does not exceed the circuit rating of the breaker.

v8440

Lemme summarize the situation: ONE TRUCK is reported to have caused a fire while plugged in, somewhere, somehow.



It'll be alright.

rammtuff

We aren't talking home invasion (which is crime) We are talking an accidental fire. Apples to oranges.
People freak out because it is a "diesel truck" Other than the engine (and a few other goodies) it is the same truck as the guy with the hemi down the road. I'm sure a big block gasser has the same size block heater that a diesel truck does.
Take anything the media says with a grain of salt.

Pop-Pop

One last comment then I'll shut up. Since there are likely some who are not "electrically smart", it is a good idea to keep it in mind when giving advice. Running a cord outside to a truck (or anything else) creates additional hazards due to rain, increased damage from weathering & physical abuse plus the fact that there may be kids around it. A cord used inside a dry garage will be safer than a cord run outside but the local electrical code usually requires a GFI receptacle in garages & outside areas. My suggestion is to take the time to do it right rather than be sorry later.

Hayseed

Unless the receptacle is rated for 750 watts which if you do the math is about 7 amps, then no that is not acceptable. Most lamp sockets are only rated for 100 watts which is about 1 amp. Roughly you will be overloading the socket 700 percent !!

jkitterman

The lamp sockets are rated for up to a 100 watt light bulb in the example you gave. It refers to the heat of an incandescent bulb. The electrical load it is capable of is entirely different.

roadrat

Pop-Pop touched on what i think is one of the most important things about useing outside plugs, a ground fault receptical, any little problem at the appliance end and power is shut off immediatly.

rob

twoshot

sorry test

tweeter

I had the opposite happen to me, a fire caused my diesel truck........see my gallery, that was a v10 inside when the garage went up (also deemed electrical), which in turned caused me to buy a diesel..............all things considered, it turned out ok

candndelivery

if the truck was in a garage, and the heater started it, it would be a vehicle fire first, causing lots of black smoke, I find it hard to beleive that if this happened in an appartment building that nobody saw, or smelled the black smoke, even if it was in the middle of the night Im sure somebody would smell it. Now if it started as an overload, arc or short, depending on fuel load, more than likely it would start out as dark gray smoke, not as easy to see and more common to smell and not think about, just like wood burning.

Ive been investigating fires for a long time and found that usually when it is said that something plugged in caused a fire it is usually how it is plugged in and not the actual appliance, or heater or whatever. The problem many fire departments have is when they think that it started in a particular peice of electrical equipment (ie heaters, block heaters, appliances, anything) they continue to open up the appliance, once this happens they usually tear up more than anything. What should be done is a phone call to the Mfg of the appliance and they will send an electrical engineer to determine if there product was a contributing factor. When this is not done the investigation will be inconclusive and the preliminary cause of the fire will be consider the probable cause, which is often wrong when dealing with electrical fires.

To those of you who are involved with origin and cause and need to get a hold of an appliance mfg you can get contacts through NAHAM (National Association of Home Appliance Manufacturers).