2003 ford f250 super duty 4x4 I live in the east, I am retired so don`t drive everyday, I am wondering how long I can leave the block heater plug-ed in, if it will hurt something leaving it plug-ed in, Thank you,
The heater is 1000 watts. It only harms your power bill. If outside temp gets warm then it might get hot enough to harm the plug but even that is long shot as that is a big chunk of iron and lots of coolant for 1000 watts to get very hot.
I can see the advantage to a timer when the truck has to be driven early in the morning since it is better than getting up at 2:00-3:00 just to plug the truck in. (Although as I get older I usually have to get up once during the night anyhow.)
But the advantage to the wall outlet (interior or exterior) controlled by the light switch is even easier than the timer for when you need the truck at random times.
Heck, these days there must be an App for your phone that lets you just tell Alexa when you need your truck and she will do it all for you...Lol
Back to the OP original question, if you are planning to leave it plugged in all the time then make sure to have the proper gauge cord for the length of extension cord you require (not too narrow) and try to choose an extension cord only as long as you need.