I have 10 trucks that I plug in here at work. Recently had new outlets installed with a timer and a temp probe. Power does not come on until it get's under 35° and the timer turns them on at 3am and goes off at quitting time around 4pm. I had it turning off at 10 am but then we needed a truck at 1 pm and it was too cold and would not start.

So today one of them didn't start, I check the breaker and it is tripped. Each truck has it's own 20 amp breaker, I'm thinking a big battery charger they used yesterday tripped it? We have only one outlet per box so they can only plug in one truck per outlet, no duplex outlets.

So anyway I sit here waiting for the truck to warm up. Already have the battery charger booster hooked up and it almost started just before after 1 hour and 45 minutes being plugged in. So I'd say at -5° it takes 2 hours to heat up a DT 466.
Man it sucks when they won't start.

I ordered a block heater on my gas powered pick up truck last year, that was nice this morning along with the remote start. Helps with my 1.4 mile drive to work.

BTW the block heaters draw 1500 watts, just like having your toaster on full time.