just how hard is it on my ole truck not to use the block heater mine starts reel good till about 15 degrees its started below 0 with out any problems
my house has alluminum wires built in the 70s prone to fires

it takes around 1800 watts for the block heater i believe it pulls the lights down pretty much in the house so i was tring to stay away from that
since my truck always starts pretty good how hard on it is it...

I will tell you what I have heard (and you know how hear-say is). I have a friend who has driven tractor trailers all of his life. He says the damage done to diesel engines comes from cold starting and shuting them off when the turbo is too hot. I have heard from a few people not to start a diesel and immediately idle it up. Diesel oil is pretty thick and needs a little time to warm up and flow smoothly before being put under pressure. A block heater helps by allowing the block to already be warm before it starts.

To answer your question, I have heard it is pretty important to plug her in when it gets cold. I plug mine in when it is going to be under 40 degrees at night. I use a heavy duty timer that comes on at 4AM and I unplug it before I start the engine at 7AM. It is nice to have a little warm air blowing out of the heater right after start up too. I have never seen my lights dim upon the block heater powering up.

me personally i won't plug mine in until it is below 0 degrees but i agree that a cold start up is hard on a motor, but its okay just as long as you give a few minutes before you drive it of idle it up, like BIG RED WOLF said, let the oil get to flowing smoothly it is a thick oil, just short of using syrup.... mine start hard but not that hard... just turns over a little slower... anways thats just my .02