As others have said, devices *draw* current/power. An outlet can support some large amount of current/power, but it eon’t supply it unless a device is specifically drawing that amount of current/power
That’s why outlets are cool with nothing plugged in. Put your finger in there and you could draw just as much current as a few devices, and it isn’t pleasant.
Think about it this way, power lines don’t know how much you’ll use. But that’s ok, they’ll just send a huge amount and you can use what you need, and the rest gets rerouted
Current vs voltage. I’m going to use NZ values, US and Europe use different, and compare it to water.
Your wall plug can deliver 240volts at 10 amps – let’s call that a 240m high pipe and watertower that can flow at up to 10 gallons a second. Voltage is how much potential energy it has (240m of gravitational potential energy) amp/current is how fast it flows.
What your power board does is magically divide that 10 gallons into up to 4 potential pipes (4 point plug)
Plug your TV into one point – let’s say 3 amps at 240 volts. The power board makes one pipe that can deliver 3 gallons per second, rest is still sitting there ready. Take note, the height of the pipe didn’t change, only how much of the flow is being used, and only 3 gallons per second are flowing – rest is sitting there chillin.
Let’s plug in something else – a heater. High draw, let’s call it 5 amps. Height hasn’t changed, still delivering 240v, but now 8 gallons per second are being used.
Now I want to plug in something else – my xbox is three amps. Oh no, now we’re sitting at 11 gallons through a 10 gallon pipe!!! What happens? In short, the xbox pulls the water through faster than the pipe can handle. It’s like blowing up a balloon too hard – your cheeks start to hurt as they are doing too much! The wires, board and stuff start to heat up. This makes it harder for the power to flow, the power gets pulled harder, repeat until something melts and the circuit breaks.
Practically speaking, your fuses will blow before then – they detect too much water flowing and close. But a shit mulitboard, wiring or seized fuses happen – and fire.
Power equals voltage times current. There is two ways you can wire circuits, in series or in parallel. Wiring in parallel gives you constant voltage and wiring in series gives you constant current. All domestic circuits are wired in parallel and have the same voltage on the terminals. To give an example, lets say a load is rated at 230W. That divided by domestic voltage of 230V gives you 1A of current that this load consumes. Having the same voltage in one socket, and also in all 3 or 4 sockets in the extension lead is why the power doesn’t split, load takes as many current as it needs and that multiplied by voltage is the required power.
Most things don’t use the entire amount of current that a breaker can deliver. Don’t think of the power from an outlet like it’s a set amount… The amount of power being delivered from the outlet depends on how much power is required by the things plugged into it.
You only run into trouble if there’s enough load on a single circuit to trip the breaker. And you’ll see that happen if you’re microwaving, using the toaster, and running a few other kitchen appliances at the same time
Imagine you have an empty hallway (extension cable) with four rooms attached (ports), each room represents an electronic device, in these rooms are power monsters that only eat cupcakes, each monster requires a constant supply of cupcakes to feed it when the door is open, so children carry them in a steady stream to make sure each room gets it’s cupcakes, imagine only having one rooms door open that needs feeding, now open two, then three….Now the hallway is buzzing with children flowing to each room….Now, try to send more children with cupcakes than necessary…They get clogged in the hallway and the whole thing shuts down, close down two rooms and you still have the children going to the open rooms but the streams to those two rooms don’t need to change.
Think of the electricity as water.
Your outlet would be like a big pipe 5 inches in diameter that can pump water at 20 gallons per minute. Think of each think you plug in as like connecting a 3/4 inch garden hose to a spigot on the front of your 5 inch pipe. The 3/4 inch hose can flow only 5 gallons of water per minute. You could connect 3 more hoses that flow 5 gallons per minute max and your 5 inch hose could still supply all of those hoses with the same amount of water.
A circuit breaker shuts off that flow if you hook up too many hoses that it can’t keep up with. In our case, it would shut a giant valve to stop the water flow so you can repair the leak without messing up the equipment. A circuit breaker literally creates a gap in the circuit, “breaking” the circuit and stopping the flow of electricity.