What are the dangers of a wall plug?

Answer 1

A child may push a small metal object in, thus getting electrocuted.

The question does not mention voltage but the voltage the outlet is supplying would make a BIG difference to the danger of electrocution if paper clips or other small metal parts were pushed into the socket-holes.

Outlets supplying 240 volts are certainly more dangerous than 120 volt outlets but even 120 volts can give a nasty shock if the person touching a "hot" or "live" contact is standing barefoot on a damp cement or earth floor or is, maybe, sitting in damp diapers (or baby nappies) on any other kind of conductive surface, such as damp carpet or damp wooden flooring laid over a concrete base.

Comment

As the questioner refers to 'switching' the socket on and off, presumably the question relates to a British 230-V, 13-A, (type G) socket outlet. With these types of socket, there is very little danger of a child pushing metal objects into the terminals, as they are protected with shutters that prevent foreign objects from being casually pushed into the line or neutral contacts. So, from that point of view, these sockets are quite safe to leave switched on, although many people make a habit of switching them off when not in use.

Further to this topic, 'childproof safety covers' should NEVER be used on British-type socket outlets, even though they are readily available in stores. The shutters built into the sockets provide the necessary safety. However, by inserting the so-called 'safety covers' into the socket upside down, a child can cause the shutters to open! In other words such 'safety covers' are DANGEROUS!!

Answer 2

There are no benefits for a residential electrical customer to unplug apliances or electronics when they are turned off. Most appliances and consumer electronics have a transformer in them to lower the voltage from the wall socket. These are the "bricks" in a laptop power chord and the large part of a cell phone charger. When plugged into the wall, weather the device is on or off, the transformer still uses current. However because it doesn't go to the electronics or appliance, this current isn't registered by your electrical meter and you are not billed for it. On a larger scale these little currents do add up. Utility companies spend millions of dollars a year dealing with these "reactive" currents which use up megawatts of "phantom power." The power companies don't pay for it out of their pockets. All customers are assumed to use a certain percent of "reactive power" and this is included in your rate. So unplugged or not, you will be billed the same. You will however help lessen the ammount of fuel burned to create that power.