There's also an answer here:
Can I test my oven temperature without an oven thermometer?
I have a big dispute with an electrician if the oven he supposedly fixed works or not. Problem is I think it reaches only about 150 C (300F) degrees when it indicates it has reached 250 C. So at 250 C (480F), I'm still able to hold my hand in the middle of the oven for 1 minute, or probably more.
When you cook next time, may you please try to see if this is possible at such temperature? I will try to get hand of a thermometer, but have nothing now, so would appreciate someone testing it.
Rephrased: Is it possible to hold a hand in the oven at 250C for 1 minute, or is it too hot?