I have an L6-20R outlet that is rated at 20-amp 240volt. The circuit breaker is a 2-pole 20/120.

I have 2 16-amp 120v power distribution units with L5-20P ends.

Could I run an L6-20P to 2X L6-20R and then convert the L6-20R to L5-20p and safely run 1.5Kw off each split without any power issues?

  • Can you trade those 120V PDUs in for 240V ones? – ThreePhaseEel Apr 21 at 13:13
  • Nope, no neutral in the circuit. Behind it, is it conduit? – Harper Apr 21 at 16:33
  • What's the Craigslist price for a 5 KVA 240-240V/120-240V transformer? – Harper Apr 21 at 18:34
  • @ThreePhaseEel They are splitting to two separate server cabinets. So I want to split the power at some point. So yeah I could buy more expensive PDUs so they both support the 240v but I'm trying to avoid accruing more costs than needed. – Justin Nathanael Waters Apr 22 at 1:05
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    @Harper Your detailed answers revealed some issues. So I'm having everything rewired from the breaker. – Justin Nathanael Waters Apr 24 at 6:47

L6-20 outlets do not carry a neutral, just two hots and ground and provides 240 volts only. As such, you cannot safely get 120 volts out of it without using a step-down transformer.

Using ground as neutral is not safe and is not allowed by the electrical code.

If you had a 240/120 volt outlet such as a 14-20, then you could safely make a splitter to two L5-20 using one hot and the neutral to each (as well as ground, of course).

  • So I can just rewire the outlet to two 120v 20amp outlets and that would fix my expensive step-down transformer issue? – Justin Nathanael Waters Apr 22 at 0:59
  • Not unless there is a neutral wire in the box, which is unlikely assuming it was originally wired for the 6-20. – DoxyLover Apr 22 at 2:32

You have a NEMA 6-20 receptacle that is (presumably) wired with 12/2+ground cable. You absolutely cannot feed two 120V circuits with that. 120V circuits require a neutral wire, and it's not present in that cable.

You absolutely can replace the cable with 12/3+ground. This is a simple unit-swap to replace the cable that is already there, identical in all respects except you put the red wire where the white had been. The white wire becomes actual neutral. At the service panel end, it lands on the neutral bar. At the NEMA 6-20R end, it is capped off and unused.

Once this is done, the NEMA 6-20 can be easily replaced with a NEMA 5-20 dual receptacle with the "hot" tab broken off, or two 5-20 receptacles that both pigtail to the netural wire. This configuration is called a multi-wire branch circuit. Neutral must be pigtailed where 2+ devices are involved, and the breaker must be a 2-pole breaker where both "hot" legs trip and throw together. That is likely already the case. If you measure between the two hots, it must be 240V.

This will provide up to 1920W continuous to either pole.

Now, in this panel, neutral and ground may be tied together. Don't get overexcited about that. That means either this subpanel is miswired, or this main panel is the point of service. This is where the 3-wire (hot hot neutral) service from the pole has an equipotential bond to the house's safety grounding system, to return fault current and assure that transformer leakage or capacitive coupling doesn't make your 120V wires float up to thousands of volts. Anywhere but this service point, neutral and ground must be carried separately. They have separate jobs and one's job interferes with the other's. That's why you can't just bootleg ground for your neutral - because then you have no ground, and several types of ordinary wire problems could cause line voltage to show up on your equipment chassis.

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