All the laptop chargers I had until now sparked whever I plugged them in. This is true for my old charger (the bulkier / rounder Dell model) and the new charger (the flat Dell model) with two different Dell laptops, however until recently I didn't give it much thought.

Then, in the last couple of months:

• I shorted out a conference room and melted the floor a little (the wire caught fire)
• The second charger (also a Dell original) died, taking the power strip with it

I'm wondering:

• Is it normal for laptop chargers to spark when plugged in? Specifically new, original Dell chargers
• Is there a "correct" way to plug / unplug chargers? Do I need to first unplug it from the wall and then from the laptop / do I need to first plug it into the wall and then into the laptop?
• May the problem be caused by the fact that I leave sometimes the charger plugged into the wall without connecting the laptop for longer periods of time (up to a day)?

PS. I'm talking about Europe, so 220V and this happens in many places (at home, at my parents, at work, in hotels I trave to, etc)