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Step down converters 220 > 110

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New Member
I volunteer at a school in New York city with a room with no 110 outlets. A 220 air conditioner outlet was installed. Is there an adaptor that will work so we can run a computer and printer (at lest in the winter) off this outlet?
220v -> 110v step-down transformers are sold at many travel stores, as they become useful when you travel to other countries, but I suspect the 220v outlet that the AC connects to isnt the kind of 220v plug youd see in other countries. Bill is right, you should be contacting an electrician and having them add a separate 110v outlet.


Most Helpful Member
Being an American installation you could just buy a 120/240 isolation transformer to get the direct 240 actual line voltage down to 120.
They are available on eBay and many other sites for around $30 - $100 new for a 1 KVA capacity (Around 1000 watts). Or slightly more for a bigger one if you plan to run more than two computers.
The plug and cord sockets you need can be found at any local hardware of building center for about $5 - $10.

The other option is to just use one leg of the 240 volt line. A school is most likely wired with 120/240 as the primary power source so just measure your voltages from both lines to the common and or ground line and see if you have two 120 volt lines that make up the 240 volt feed.
If so its possible to just make a cord adapter that splits the two lines that feed the 240 volt power into two 120 volt lines directly.
If you do have the two line feed system I would recommend using outlet strips with built in circuit breakers for safety reasons. Some 240 volt AC unit power lines can be 30 amps or higher.

All of this is plug and play stuff and not hard wired in so its completely legal from the NEC rules and requirements stand point being a 240 volt circuit can in fact use the ground line as the common line in a three wire dual circuit set up. ;)

The last and most obvious method is to just plug the computer right into the outlet directly being typical computers have the world wide power compatibility built right in. That meaning they are factory equipped to run on around 100 - 250 volts AC at 47 - 63 Hz just by changing what type of cords they use. Although you would have to make up a simple distribution box to run the monitor and other stuff too. Just look at the input power ratings on what you have to see if its all universal power compatible rated.

Nit pickers be dammed. This is what shop class is supposed to be teaching high school kids before 10th grade anyway.:D
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