I am trying to create a computer charging station. I have many laptops and Android Tablets that I would like to charge at once. Assuming I wire it correctly, how many adapters can I put on 1 plug?

Laptops are 40W charger cords.

Tablets are 10W charging blocks.

  • The figures you quote are for the "output" of the chargers. What are the specs for their inputs? They'll likely be listed as some amount of current at some particular voltage. Do you how much current your circuit can deliver? In the USA, it would be either 15 or 20 A. – Pigrew Aug 22 '13 at 4:29

36 laptops,
144 tablets,
18 laptops and 72 tablets,
Any combination of laptop and tablet that is less than or equal to 1440 watts.

Since a 15 ampere 120 volt circuit can supply a maximum of 1800 watts, but a circuit should only be loaded at 80%.

15 amperes * 120 volts = 1800 watts

1800 watts * 0.80 = 1440 watts

This example assumes that this is a dedicated circuit, with no other loads on the circuit.

  • Dedicated 20A circuit - 1920 watts – Fiasco Labs Jul 13 '13 at 14:50
  • +1 But that assumes that nothing else is on the circuit (and remember that, in almost all cases, not just one outlet is on the circuit). If other things share the line, adjust accordingly. – bib Jul 13 '13 at 17:18
  • 1
    You really shouldn't assume a country when answering questions like this. – user13406 Jul 13 '13 at 18:28
  • @bib Please see the small print at the bottom of the post. – Tester101 Jul 14 '13 at 0:18
  • @Lee I show the maths, so it can easily be applied to any country as long as you know the voltage and amperage. – Tester101 Jul 14 '13 at 0:20

It depends on which country you're in, and its electrical circuits. Basically, a certain number of sockets will be connected to one circuit in your electricity box (the fuse and switch box, where the mains comes into your house and is connected up to the different sockets / lights / cookers etc. through fuses).

Some people above have given you the ratings for 120V US sockets. In the UK, it's 240V and up to about 3KW, so you can roughly scale these accordingly. BUT, bear in mind that the voltages are different and need conversion (see Ohms Law) and, don't forget to count anything on the same circuit that's already using power. For example, if you hook all this up and it runs at the maximum load, but then your tumble dryer switches on, on the same circuit, you'll be in trouble.


My charger says it draws 1.7 Amps. If I plug in all of the devices at once, and they all are in desperate need of a charge, the chargers will be running at full capacity. Now, if the circuit is a common 15 Amp circuit, and nothing else is plugged in along the line from the breaker box to the computers, then 15/1.7 = 8 chargers.

IF you are in a modern building, and IF it is wired correctly, you will burn out a fuse or "pop" a breaker switch before you start an electrical fire.

If you can plug in all of your devices without tripping the fuse or breaker switch, then you are good to go. I am in a North American school, and we have 95 chargers plugged into one outlet (chargers are plugged into power bars in the backs of the carts that are plugged into a heavy duty power bar that is then plugged into the wall). Students take computers and bring them back all day long, so all 95 have probably never been plugged in all at once in an almost dead battery condition.

We do not have any problems with breaker switches "popping".


If there are no other loads on the circuit, you can pull 15 amps @ 120VAC = 1800 watts per circuit. Let's say 1500 watts to have some headroom.

You can easily figure out how many laptops or tablets you could charge at once.

  • 1
    Circuits should only be loaded to 80%, which would be 1440 watts on a 15 ampere circuit. – Tester101 Jul 13 '13 at 14:08

It does not depend up on your load, it depends on your installation computer charging station wire size. 0.5, 1.0, 1.5, 2.5 core wire. If you want a 6 amp load connect supply then you use 0.5 core wire. 1 core is used for 8-10 amp current.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.