Yes block heaters work great, three hours warmup is plenty even at -45F. I also have heaters on the tranmission and engine oil pans and a battery blanket thats heated. All connected to a outdoor timer.

 

The mat will catch fire, not the cord.
This is not the cord catching fire as I noted above. It is the rug or mat. The cord under the carpet that gets walked on ( and damaged ) creates a resistive heating circuit ( like the block heater ) , which in turn ignites the carpet, again not the cord itself. A cord in good repair will not catch fire. If the Darwin candidate using the cord puts it under a rug or mat, that is the gene pool thinning itself out, and the rug or mat catching fire.

BTW : The coiled cord creates an inductive field that acts like a heating circuit. The cord would need to be a 16/2 or 18/2 cord, 25' long, with 20' coiled under the carpet, and a 15 amp load on it, for hours on end to make your example work ( i.e. get the inductive field hot enough to ignite the mat, the qty of hours depends on how flammable the mat is, and what the flash point of the materials in it are ).

Also if you read my post, 30s for temp range for 2.5 hours is enough to get the truck into operating range. Doesn't take 4 hours using the example I gave. At sub 0 maybe, but this is a post for a person in TX, usually 30s is about all he is going to be seeing.

 

Do you think a 15amp timer would work? Also what gauge extension cord would work best for plugging in the truck? Thanks

 

This thread is from 2004