The convenience of leaving the devices connected made it a common practice. These chargers constantly draw energy, but not as much as they would if they were lit. This could lead to a fire risk either by heat accumulation or by short circuit.

The use of the correct extension cord is essential for your safety. With continuous use over time, an extension cord can quickly deteriorate, creating a potential danger of shock or electric fire. Several plugs must be connected directly to the mounted electrical containers that cannot be launched together.

Any electrical device that remains connected to the electrical network could cause a fire. Some, such as refrigerators and freezers, are designed to be left on, but even these can cause fires if they are not used properly.

No, this is safe as long as the battery is not in the charger. Some chargers may have a little power drain to be connected (even when it does not charge anything), but should not do any harm to the device to let it connect.

Without a blocked object, there is no chance that it will catch fire. Once it does, there is a chance that the item will catch fire. The risk or probability that it will catch fire is statistically low enough. If the plug has a switch on it and the switch is off, then the probability is even lower.