How do extension cables or power strips supply power for 3 plugs if they’re only plugged into 1 outlet?
In: 35
They can do more than 3.
An outlet on a 15amp breaker can supply about 1800W, so you could theoretically hookup 3 600W appliances and see no issues. It’s about wattage delivery.
The one downside to power strips is overloading and using it with high voltage appliances that the internal wiring of the power strip cannot handle, which is dangerous.
Because each outlet in the power strip is not supplying more than the max power that the outlet it’s plugged into can provide. If anything plugged into a power strip were to draw the max electricity the breaker would trip to protect the wiring and other things plugged into it. Power strips are about the ease of on demand electricity for multiple appliances, not power amplification.
How does a sprinkler attachment or spray nozzle attachment for a garden hose supply water into 10 different streams of water when it’s only plugged into one hose? The same way.
If a power strip has 3 plugs, those three still can’t add up to more than the one outlet can provide. The function of the power strip is just to provide more physical space for plugging things in. Like phone chargers and old laptops with those bulky blocks at the plug. Each one may only use 5% of the power the outlet can provide, so the limitation is physical space if one of those blocks occupies 1 or even 2 outlets and prevents you plugging anything else in. So instead you plug in a power strip to the outlet. This does not provide any more capacity to deliver power. This provides physical space to plug in more things to whatever capacity that 1 outlet already had.
You still can’t operate things off the strip that add up to using more power than 1 outlet can provide.
You can [look inside one](https://upload.wikimedia.org/wikipedia/commons/f/fd/Power_strip_inside_with_plug.jpg) to see how it works. The hot side has a bar that touches all the hot pins and the neutral side has a second bar for the neutral pins. In a three-prong strip, there’s a third bar for the ground pins.
One thing to remember is your 2 socket wall outlet only has 1 wire connected to it going to your breaker box. Everything plugged in just shares the power that one wire can provide, and it’s all arranged in parallel [like this bulb and battery arrangement](https://i.ytimg.com/vi/SqtEbjDHlLs/maxresdefault.jpg)
Typical residential circuits are wired for 15 amps. That’s a unit of current. Think of current in electricity as the same as water flow in a pipe.
The wiring is only designed to be safe for 15 amps. To prevent the wiring from getting too hot and burning your house down, each circuit is protected by a circuit breaker – which opens up (shutting off the electricity in that circuit) when it “sees” currents of more than 15 amps.
Most things you plug in don’t use 15 amps of “flow”. Typical electronics (that you would plug into a power strip) use only a fraction…or just a “trickle”. Your phone charger, your Xbox, your monitor, your laptop, etc….all use between 1/2 amp to 2 amps each.
You could easily plug six of these type items in and be fine. As long as you stay below 15 amps total, the circuit breaker won’t trip.
If you plugged a toaster (5 amps), microwave (8 amps), a kettle (2 amps), and a hair dryer (10 amps) into a power strip and turned them all on, you’d have a problem.
What is electricity? Two disconnected conductive pieces of material with a different number of wandering electrons have a “charge” between them. The moment you connect them, the electrons will flow from the one with surplus to the one with deficit.
By letting the electrons march through the filament of a lightbulb, or the windings of an electric motor, you make them do work on their way.
Electrons will march on any bridge between the conductors, no matter the size, shape or number. If you connect 5 lightbulbs all will light up. A power strips is just a convenient way to extend the range of the conductors and branch them for easier access.
OK, the actual ELI 5 answer.
Imagine that electricity is flowing like water in the wires. Theres only room for so much water flow, but even a third of that flow is way more than enough for a device that consumes little power, like a desk lamp. If you plug several power tools in, they might have a problem (depends on area, the powerboard, and the appliances).
I have sometimes shorted my kitchen one by running a kettle, the fridge and a convection stovetop all at once. It can handle two, but not all three. If I were to run a light, the fridge and the kettle, it wouuld be fine, as the light uses little power, and the convection top a lot.
It’s like splitting water in pipes using tee fittings. You can’t exceed the maximum capacity of the outlet with all three devices connected to the extension/power strip just like the total flow can’t go above what the pipe before the tees is providing.
There are three things that dictate how many pieces of equipment you can connect to the same power strip or extension cord.
1. The capacity of the outlet. In Canada and the US, that’s usually 120 V 15 amps, so about 1800 W. Devices that max one outlet like a space heater are typically limited to 1500 W, that leaves some margin.
2. The number of plugs on the power strip/extension
3. The capacity of the wiring in the extension and power strip. This is often forgotten and can be a fire hazard. The wire gauge (how “thick” they are matters. You will see extensions listed as having 14, 16, 18 Gauge wire, etc. The lower the number, the thicker the wires in the extension. Thinner wires cannot carry as much power without heating up too much. Cheap household extensions can have relatively thin wires. Thin enough that maxing out the capacity of the outlet using an extension like that could be a hazard. If you’ve ever noticed that extension cords construction workers use to power thinks like air compressors are thick, it’s not just so that they are sturdier, it’s also because they have thicker higher quality wiring. You can certainly use a cheap extension to power a lamp, but don’t use it to power a space heater if it’s not rater for it.
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