208V/120V 3 Phase Power Distribution

In this video I go over the theory of a 3 phase 208/120 Volt power distribution system. I show a real life example and the voltages associated.

[waynenocton]

I’m used to this, but recently I finally got to work around the 120/240 3 phase with the 208 volt high leg, that was really strange. People were so afraid of the high leg that they pulled the fuses to the high legs at the service disconnects, but that way it can never be balanced, so I’m using the high legs and one other leg for each and every 240volt device, then when everything is finally done and working, I plan to balance things using a clamp on amp meter. I’m not a licensed electrician, but I do what I can before calling in the electricians to check everything and fix any issues prior to inspections, saves my boss a whole lot of money that way.

[BobbaFett]

your transformer shows 240/120 secondary, should it show 208/120 instead?

[jaeiii]

Nice video. I’m working on this exact set up for a friend. His set up from the power pole is feeding a 200amp disconnect from the meter. Now I’m curious I’d like to bring 400amps to upgrade so I can have 2 200amp sub panels. My question is…. Do I have to upsize the wire from the utility pole?

[derekc]

Thank you for the thorough explanation. Got a curious question and this always stump me. What voltage do you get when you are tapping this in a three phase breaker for this Y transformer configuration? whenever you use three phase, does your power goes up since there is a factor square root of 3?

[uripiru]

Where is GEC ? grounding electrode conductor that goes to ground ( grounding electrode). I am not sure if your local code follow NEC.

[TofuInc]

It's actually less than 1/10 amp that's returning via the ground conductor. It's only the unbalanced current. If the primary side was wired as delta instead of star, no neutral connection would be used.

[GH-oijf]

The "delayed start" angle is meaningless. All three waveforms should start at the left side of the plot.

[highvoltage]

Your disconnect needs to be bonded to ground