Powering 3 phase Equipment

[Dansos]

Hi Guys,
I don’t do too much work with 3 phase power. My friend has a warehouse with a 120/208V 4 wire Panel. I am not sure of the “correct” name but I always called it a stinger leg. I get
120LN 120LN 208LN and 240 to any combo of lines. He wants to hook up a Heat Tunnel that is calling for 3PH 220V 40A. The tunnel has an input terminals labeled L1 L2 L3. Will a 3 phase 40Amp breaker deliver 220V 3 phase power? I am pretty confident it will work but I just want to double check with some experienced members who have worked on these setups before.

 

[ptonsparky]

We call it a Hi Leg Delta. The 340 wil deliver the 3 phase.

 

[LarryFine]

Hi Guys,
I don’t do too much work with 3 phase power. My friend has a warehouse with a 120/208V 4 wire Panel. I am not sure of the “correct” name but I always called it a stinger leg. I get 120LN 120LN 208LN and 240 to any combo of lines.

That is NOT a 120/208 supply, which is correctly called 208Y/120 3ph. What you have is a 240D/120 3ph with a high leg. The two 120v lines and the neutral are exactly, and I mean exactly, the same as the 120/240v 1ph that supplies your home. In fact, the high-leg Delta supply began as a modification to existing 1ph services to accommodate the addition of 3ph equipment.

He wants to hook up a Heat Tunnel that is calling for 3PH 220V 40A. The tunnel has an input terminals labeled L1 L2 L3. Will a 3 phase 40Amp breaker deliver 220V 3 phase power? I am pretty confident it will work but I just want to double check with some experienced members who have worked on these setups before.

Yes. Don't let the discrepancy between 220v and 240v throw you. Ignore that the service has a neutral and ignore the fact that one line has a higher voltage to ground/the neutral, except that the high leg should be orange instead of red (presuming the black/red/blue color coding is otherwise used) and keep the high leg on the center terminal of any 3-pole disconnects and/or switches.

 

[drcampbell]

For 3-phase, 240-volt loads, use the three hot wires (A, B & C) and do not connect the N.

 

[LarryFine]

For 3-phase, 240-volt loads, use the three hot wires and do not connect the N.

View attachment 21000

Didn't I just say that?

 

[kwired]

That is NOT a 120/208 supply, which is correctly called 208Y/120 3ph. What you have is a 240D/120 3ph with a high leg. The two 120v lines and the neutral are exactly, and I mean exactly, the same as the 120/240v 1ph that supplies your home. In fact, the high-leg Delta supply began as a modification to existing 1ph services to accommodate the addition of 3ph equipment.


Yes. Don't let the discrepancy between 220v and 240v throw you. Ignore that the service has a neutral and ignore the fact that one line has a higher voltage to ground/the neutral, except that the high leg should be orange instead of red (presuming the black/red/blue color coding is otherwise used) and keep the high leg on the center terminal of any 3-pole disconnects and/or switches.

If it is an older installation where they often had high leg on the right, you may want to keep new stuff consistent with that arrangement, and I'm pretty sure NEC does allow it in those situations.

 

[LarryFine]

Here, the POCO requires it on the right in the meter base, but we're supposed to transpose it to the center for everything downstream.

 

[kwired]

Here, the POCO requires it on the right in the meter base, but we're supposed to transpose it to the center for everything downstream.

Yes that is generally what you are supposed to do now. Some cases you still may have to put high leg on right just because equipment with a meter in it needs the high leg on the right for the meter to work correctly. That and if you have an older facility that has the high leg on the right throughout the place, you may actually create more hazard and confusion if you start changing things from what is already there.

 

[Dansos]

Thanks for the replies. I figured the neutral was not needed for th equipment. So to understand this system better, the neutral would ONLY be is used for 120V feeds. Other then that, the 3 legs will be ran with the ground for anything requiring 3 phase power?

 

[LarryFine]

Correct. Look at Dr. Campbell's diagram more closely.

It's a typical 120/240v service with a Delta superimposed on it.

For three-phase loads, only the 240v line-to-line matters.

For single-phase, only the 120v line-to-neutral matters.

 

[drcampbell]

Didn't I just say that?

That you did. I thought an illustration would be helpful.

 

[infinity]

Thanks for the replies. I figured the neutral was not needed for th equipment. So to understand this system better, the neutral would ONLY be is used for 120V feeds. Other then that, the 3 legs will be ran with the ground for anything requiring 3 phase power?

Yes, with the Delta systems (3 wire or 4 wire) you'll end up with 3Ø, 240 volt supply to your equipment and you'll only need the three phase conductors and an EGC. The Wye system is completely different.

 

[GeorgeB]

At the risk of being off-topic, I'd like to suggest that you ensure the "Heat Tunnel" is heater loads only, not including a variable speed inverter drive for a conveyor. The inverter variable speed drives have quirks fed from a delta supply that require special consideration.

 

[kwired]

Also if any supplied equipment has 3 phase major load but also has 120 volt lights, controls, or other items, you do need to pay attention to where you land the high leg in your equipment - unless it has a control transformer within to derive the 120 volts.

 

[Dansos]

The heat tunnel came with a twist lock plug coming out back of it. We disconnected that bc the client wanted a little bigger whip. It was L1 L2 L3 at the line terminals so I didn’t think phase would matter where it went. It’s hooked now and seems to be working fine. Thanks guys for all the help!!!