Do power outlet splitters decrease power for each deviced connected to them?

If I have a one to three outlet splitter, would this mean that each outlet only gets one-third power, or do all three get full power?

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Read up on parallel versus series circuits – Steven Feb 6 '14 at 1:17

Your outlets themselves are splitters: in general several outlets share a run of wire back to the power source. The external "spliter" is no different, it just provides more connection points to the same electrical circuit.

However: the total circuit capacity is neither increased nor decreased by a splitter. Devices "draw" current based on their needs: for example a motor generally draws more power when loaded than when spinning freely. If the total draw exceeds the circuit capacity, a protective device will trip. The protective device is usually set at 15 or 20 amps in a residential circuit.

Extra connections or total extension cord length can have a minor effect: a long thin cord with a heavy load can heat up, using up some of the electricity in transmission. In effect the wire becomes an electric resistance heater. This effect is usually negligible.

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+1 tweaked your answer a bit. check to see if you agree. – bib Feb 5 '14 at 23:27
Actually the amount of power available is decreased slightly due to contact resistance, and the conductor loss in the device. The total losses should be so little as to be unnoticeable though. ( If you can notice the loss, something needs to be replaced. ) – Brad Gilbert Feb 6 '14 at 5:14
What if the outlets are a few hundred feet apart? – DMoore Feb 6 '14 at 16:10
Does not address the question. Question is about the devices receiving power which are plugged into the splitter (not just the outlet itself). Also, having additional devices plugged into the splitter would change the total power provided. Is this answer better: (diy.stackexchange.com/a/38793/19724) ? – Aaron Klap Feb 6 '14 at 17:57
The answer is correct: devices plugged into the splitter will see no meaningful difference. Your outlets are splitters also, an external splitter is no different. You can draw power up to the point where the total draw is exceeds a limit. – Bryce Feb 6 '14 at 18:49

Electricity doesn't work like that. At any given moment, there is an infinite amount of "power" available. However, as electricity flows to the device, heat is generated due to resistance along the pathway. If the pathway gets too hot, it will be damaged. Because of this, we use breakers and fuses to prevent the pathways from overheating.

Each device connected to the system will be able to use as much electricity as it wants. But once the pathway gets too hot, the breaker will trip or the fuse will blow (or the pathway will be destroyed).

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TL,DR; You get 120 volts always. Adding more devices makes the circuit deliver more AMPERES.

Within operational parameters, your wall outlet will deliver 120 volts. Every regular outlet in your house will deliver this voltage. You can think of this as analogous to water pressure at the bottom of an enormous tank - no matter how many taps you have at the bottom, the pressure will be the same at all of them.

For reasons of safety, your outlet is fused in the panel (actually the entire circuit, but keep it simple) at 15 amps. Amperes is the measure of current, or the amount of electrical charge flowing through the circuit. This is analogous to the amount of water flowing out of a tap. (The word CURRENT is even borrowed from fluid dynamics).

NOTE: Resistance values are completely made up. Actual values are in the 250 Ohm range

So, your phone charger has a resistance of 30 Ohms. According to ohms law (I=V/R), that means the current in your circuit is 120/30 = 4 Amps. Thinking in terms of conductance, Ohm's law becomes I = VG, which is I = 120 *(1/30) = 4 Amps. (same thing).

Now lets add a second phone to the circuit. The total Conductance will be 1/30 + 1/30 = .06666... We now have two paths for the current to flow, so our conductance has doubled. 120 * (0.0666...) = 8 amps. And so has our current.

Add another, and the conductance will be 3 * (1/30) or 0.1 and the current will be 12 amps.

Add another, and the conductance will be 4 * (1/30) or 0.1333333, current will be 16 amps.

At this point we are dangerously overloading the circuit. The wires in your wall will start getting hot, and there is a potential of fire. This is why your breaker will flip -- to protect the wiring from overheating.

In reality, your circuit is already split. One breaker in your panel typically feeds several outlets and lights. That's why if you were to vacuum, Iron, make coffee and toast in your living room, you'd likely blow the breaker. The conductance would go through the roof and current would follow.

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There is two kinds of power. There is "pressure" and there is "amount".

The pressure is unchanged, so you can run the same devices and they will work exactly like before.

But the amount of electricity is also unchanged, but, now it has to be shared. Since usually devices don't need the full amount available to them (they only take what they need) this works.

But if you had 3 devices that all took the maximum amount of electricity possible then it wouldn't work - there's not enough.

The thing I call "amount" is really called "watts". The maximum watts from a single outlet is 1,800. (1,500 is more realistic.)

So add up the wattage from each device (it's printed on them) and make sure not to go over.

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Your amount should actually be amperes not watts and as the ratings for fuses and breakers are in amperes and as that makes the advice independent of the voltage. – Dan D. Feb 6 '14 at 8:33
@DanD. I'm trying not to confuse the asker. People are pretty familiar with watts, amps not as much. – Ariel Feb 7 '14 at 4:56

No, devices don't get less power when using a splitter, each device plugged into the splitter will get its required power. The only time this won't happen is if you overload a circuit.

A common misconception is that one outlet gives a set amount of power. If this were the case, the more items you plug into an outlet the less power each item gets. So what actually happens when you plug more devices into an outlet using an outlet splitter? The outlet provides more power! But there is a limit. This is best explained using an example.

How does your outlet know how much power to provide:
Say there is a single to triple outlet splitter plugged into a wall outlet in your living room. Lets also say you have three lamps which use 120 Watt light bulbs which operate at 120 Volts and draw 1 Amp each. Lets also say you want to power all three at the same time using this splitter. A single bulb draws 120 Volts and 1 Amp, equating to a power usage of 120 Watts. If you plugged all three lamps into the splitter at the same time, each bulb would still draw its needed voltage and current. Because the bulbs are hooked up in parallel, the total Voltage drop your livingroom outlet experiences is the same while the currents gets added together. This results in a combined total of 120 Volts at 3 Amps, equating to a power usage of 360 Watts. Although the 360 Watts is "split" between the bulbs, this does not reduce the needed power (120 Watts) each one of the bulbs gets.
If the livingroom outlet is protected by a 15 Amp fuse, then there is no problem because the combined current draw is only 3 Amps. But if you are charging equipment with a combined total current draw of more than 15 Amps, the fuse will blow. No need to worry though, fuses are designed to fail so the equipment you plug into the outlet won't be damaged. Most household equipment doesn't use anywhere near 15 Amps, so this is usually a non-issue.

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This is a bad example since a transformer is involved. If you draw 3 amperes @ 5 volts on the secondary, you'll only see 0.125 amperes @120 volts on the primary. 120 Watt light bulbs @ 120 volts might be a better example, since each bulb will draw 1 ampere. So in theory, you should be able to have 15 120W bulbs before the breaker trips. – Tester101 Feb 6 '14 at 18:59
Thank you very much for the feedback, forgot about the transformer. My example has been corrected. – Aaron Klap Feb 6 '14 at 22:53