How to Double the Power
of a Standard Wall Outlet
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Technical Support Information
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Often the question is asked: “How can I get more power into my room?” This bulletin offers a simple, safe and highly cost effective solution that is ideal in many situations and it is not necessary to change or to add more circuit wires to get more power. -- “How to upgrade a 120-volt outlet to 240-volts.

Note:  This procedure is not to be used with “Edison” type circuits (typically where a red and black pair of circuit wires feeding outlets share a single white neutral.)  Check inside the circuit breaker panel to verify the circuit type.  Check to see that only a black (or other colored wire) and white wire are present that feed the outlet to be changed.  A green or bare wire should also be present for proper grounding.  Presence of another colored  wire (often red) run with a black and a white generally indicates and Edison circuit.  However, if there is one white wire for each line conductor in the run between the breaker panel and the plug, this is not an Edison circuit and it is OK to use the following procedure.


1.)  Under ideal conditions, one would select an existing dedicated outlet that is fed from a single circuit breaker. There should be three wires feeding this outlet: a black, white and green wire (sometimes the green wire is bare copper). The color of the hot wire is not important as long as there is a “hot” (120 Volts), a neutral (zero Volts) and a ground wire present. If the selected outlet is dedicated (one outlet on the circuit-breaker) skip to step 3.

2.)  If there is a chain of outlets on a circuit, select an outlet that is conveniently located, remove it and the rest of the receptacles on the same circuit in the following manner:
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  • Turn off the power.
  • Remove all of the outlets on the circuit and disconnect all of the wires. Check the stripped wire ends for damage or the possibility of wire stress and restrip the wire ends if necessary.
  • Put red tape around all of the white (neutral) wires for safety. Red tape indicates that 240-volts may be present and white is not to be regarded as a neutral to anyone who later might open the outlet box.
  • Using wire-nuts, reconnect by color all of the wires removed from the receptacles-- white to white, black to black, etc. If there are no wires to connect with wire nuts at a particular location, cap off the wires anyway.
  • Cover all of the non-essential outlet boxes with an appropriate blank plate, leaving the selected outlet unfinished for now.
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3.)  At the selected outlet location, using the black white wires for power, install a 20-amp 250-volt receptacle (NEMA 6-20R). First inspect the wires first for physical damage or stress and restrip if necessary. Be sure to properly ground the receptacle.

4.)  Locate the appropriate circuit wires in the breaker-panel and disconnect both the hot wire from the circuit-breaker and the white wire from the neutral buss. Put red tape on the neutral wire.

5.)  Install a 2-pole circuit breaker in the panel with the ampacity rating that is appropriate for the circuit wires (15-amp for #14 gauge, 20-amp for #12 gauge.)

6.)  Attach the black and white circuit wires to the 2-pole breaker, one wire per pole. Restore power to the circuit.

7.)  Replace the breaker panel's cover.

This completes the upgrade installation of a 240-volt 15- or 20-amp receptacle outlet with enough power capacity to run an ET3R or ET4R Equi=Tech rack system (capacity of 30- or 40-amps @ 120 Volts.)

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