No need to hire an electrician as every home and office has the ability to make 240 volts. Installing an permanent electrical 6-20R receptacle can cost between $800 to $1500 and mean taking a day off work. This box eliminates that need while while having the flexibility to take the power with you. To use simply plug into different standard 120 volt wall outlets and push the momentary button to test voltage. If the green light turns on, you are good to go. Not all outlet combinations will produce the correct voltage so you have to test before each use or each time you take your box to a new location. If you push the voltage test button and the green light does not turn on, simply re-located one of the power cords to a different location and retest. Every job site location has the ability to provide 230-240 volts. If you use 15 amp 115 v to 120 volt circuits then you will only be able to operate 15 amp 230 volt equipment. 20 amp dual outlet recommended.