240 Volt 3 wire (split phase) Ballast Bypass Wiring instructions and diagram

Posted by Sam T on 4/27/2017 to LED Parking Lot Lights
240 Volt 3 wire (split phase) Ballast Bypass Wiring instructions and diagram

240 Volt 3 wire (split phase) Ballast Bypass Wiring

So you are trying to change to LED Lights with 240volt but now you have 2 hot wires and a neutral/ground coming out of the building.   How does this even work?  Where is my return?   What do I connect to?   We have some answers for you. 

What is 240v ac Split phase?

In the USA, 120v and 277volt use 3 classic wires.   A hot, a neutral and a ground.   This is the electricity we have all be taught about.   240vac  (v=-volt, ac=alternating current)  throws a spin at you.   It uses 2 hot wires at 120v each that alternate positive to generate the full 240v and a ground that acts as a neutral (not a normal neutral as if this isn’t confusing enough)  By combining the 2x 120v wires you get 240vac.    We’ll spare you the technical details of 240v and its advantages and disadvantages, but Wikipedia does a good job explaining it, head there.   We are going to focus on getting the job done and getting the LED light bulbs, parking lot lights or other installed.  

Black, Red and Green wire?    Black, Black and green(or other random color)?

Yes, in a split phase setup you commonly have Black=Hot, Red=hot and green=neutral/ground   Sometimes you see two hot wires both as black.  So that is Black=hot, black=hot and green(or whatever they want)=neutral/ground, but that is less common.

There is a ballast, how do I wire my 240vac to the socket or LED driver?   

Yes, most of the time when retrofitting to LED Light Bulbs you will have to bypass the ballast and wire direct to the light socket.  That is because higher lumen output bulbs like metal halide, HID or CFL all require a ballast to work correctly.   LEDs use a driver and not a ballast.   If you are replacing an incandescent then you will not need to.   The good news is that rewiring is easy to do.   You are literally cutting the ballast out of the system and throwing away.  Then taking those wires and direct connecting to the socket or driver.

How do I wire the 240volt 3 wire light socket?

Whether it is a classic E26 or larger mogul E39 light bulb we recommend the same thing.  Treat the red wire as the hot and the black as the neutral.   Connect these direct to the socket.   In theory you will have actually have 120v to the socket, not the full 240v but that is fine for LEDs.  

Doesn’t it work better on 240v or 277v?

No, LEDs do not care.  Unlike Metal Halides that worked better with more juice, and even required a pulse start setup for optimal performance, the LEDs just do not need it.   In fact, the LED Driver inside an LED Corn Buulbs downgrades the power from AC to DC for each of the LEDs.

What if there is a separate driver?   Or just brown, blue and yellow stripe wires?

If you are not retrofitting a light bulb socket, but a whole LED high bay light fixture or LED retrofit kit with driver, you do the same thing.   Connect Red to Brown and black to blue.   If they are using American wiring instead of international, then its red to black and black to white.   Ground is always the same.

What does the wiring look like?

Here is the technical;

240volt ac split phase wiring


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