Respectfully request advice in using a three phase breaker for a single phase circuit

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Installer

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DesMoines, Washington
This is to request advice in using a three phase breaker for a single phase circuit

1. The Outdoor panel on the left is 120/208 VAC and is fed from a 3 phase Square D I Line Panel 700' away.

2. We need to replace the Outdoor panel because because its outdated and has Two Hots and a Neutral but no Equipment Grounding Conductor.

3. We only need single phase 120 VAC 40 A service at the Outdoor panel. (One Hot, One Neutral, One Ground)

4. Can I make things right by re-purposing the 120/208 2H and 1N conductors as 120 1H, 1N, 1G conductors and reconnecting them to one pole of a 3 phase breaker?



[FONT=ArialRoundedMTforSE_Latin] "Yes. Order a standard I-Line panel and only order breakers that are phased A-C."[/FONT]

So my question is :
1. If I find an I Line circuit breaker that is phased A-C, can I only use phase A on that breaker? ( we only need 120 VAC)

2. More importantly, can we take the two hot and one neutral conductors and re purpose them as one Hot, one neutral and one ground inside the I-Line Feed Panel?

Thanks in advance
Respectfully
Installer

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1. Curious. What is the wiring method between the panels ? (a conduit system might provide an equipment ground)
2 What size feeders conductors are we discussing, Conductor identification requirements on smaller than #6 might pose a problem
 
If you are using a breaker you already have, yes you can hook up to just one pole of a multipole breaker and it will work fine.

If you are going to order a breaker, why not get a 1 pole breaker? Looks like they don't have them in the Q series (240 volt rated) but do have some that are 277 volt rated. Those will still work with 120 volts.
 
augie47 said:
1. Curious. What is the wiring method between the panels ? (a conduit system might provide an equipment ground)
2 What size feeders conductors are we discussing, Conductor identification requirements on smaller than #6 might pose a problem
Click to expand...

Minor correction........
Its conductors smaller than #4, the wording is confusing if read fast. "Sizes of 6 AWG or smaller" & "Sizes Larger Than 6 AWG"
The 6 and smaller have to be factory marked/colored w/exceptions
The 4 and larger may be reidentified.
I don't know why they couldn't have said "sizes 4 AWG and larger..."
 
I am not sure if the conductors wires are #4 or #6 AWG.
Some people have that ability to size wires and diameters and pitch and threads instantly.
I definitely do not!
I'm going to ask for a shutdown and enter the Feed panel and make sure everything is right
before proceeding.
wire size.jpg
 
Can't tell from the picture but looks like #6 or #8 for the larger white one and maybe #10 and #12 for the others.
But the line conductors is what you would need to see if they are to be reidentified.
 
Jraef said:
I still don’t get why you are using an I-line panel and a 3 phase breaker at all. Just because you already have it?
Click to expand...

I may have confused readers. I've done that before.


  • The I-Line 3 phase panel is the Source Panel at a Building 700 feet away. A 3 phase circuit breaker on that panel feeds a 3 conductor line (120/208 VAC 2H 1 N) which runs under a parking lot and a grass field to the Small panel we are replacing.



  • That small panel is 120/209 but we only need 120


  • Having just replaced a similar 1000' line with new conductors and conduit in July, I really don't want to repeat that. Our crew was exhausted in the heat and when we had to hand dig at certain areas I was the one who had to hand dig and I'm an engineer (Whoopie Doo that makes me the low man on the totem pole:D)


  • So I want to reuse the Conductors and I'm stuck with the Source Panel but I can change the breaker.


  • What I want to do is change the field panel to 120 VAC Single Phase and repurpose the Conductors
 
What size are the feeder conductors? We need to know to advise you further. The insulation should be marked.
 
Installer said:
2. More importantly, can we take the two hot and one neutral conductors and re purpose them as one Hot, one neutral and one ground inside the I-Line Feed Panel?

Thanks in advance
Respectfully
Installer

View attachment 23482
Click to expand...

That would seem to be the best 'out' aside from digging Installer. You know the old 250.32B would allow you to keep it as is, marry GEC's to an MBJ right there.

alas, times have changed....

~RJ~
 
Installer said:
I may have confused readers. I've done that before.


  • The I-Line 3 phase panel is the Source Panel at a Building 700 feet away. A 3 phase circuit breaker on that panel feeds a 3 conductor line (120/208 VAC 2H 1 N) which runs under a parking lot and a grass field to the Small panel we are replacing.



  • That small panel is 120/209 but we only need 120


  • Having just replaced a similar 1000' line with new conductors and conduit in July, I really don't want to repeat that. Our crew was exhausted in the heat and when we had to hand dig at certain areas I was the one who had to hand dig and I'm an engineer (Whoopie Doo that makes me the low man on the totem pole:D)


  • So I want to reuse the Conductors and I'm stuck with the Source Panel but I can change the breaker.


  • What I want to do is change the field panel to 120 VAC Single Phase and repurpose the Conductors
Click to expand...
If you repurpose the conductors as a single 120V circuit, you will lose capacity. Why are you worried about this? You can have a 120/208 single phase panel and all of the loads can be 120V. You don’t need to change anything.

But to directly answer your question, there is nothing stopping you from using a 3 pole breaker for a single pole or two pole circuit, other than there being a waste of money for the breaker. The only thing stopping you from wasting your efforts in repurposing the conductors might be the color of them. Neutral must be white, ground must be green or bare. You may be able to use colored tape on the ends to identify them, you may not (depending on code sections regarding size and whether they were originally identified by insulation color). You should ask that question in advance of your AHJ.
 
I did it at a shop in the waay outskirts and they happened to have a brand new 3p panel fed by 120/240.
If a mlo sub id sugget heating up L1 and L3 on on one leg and the other leg on L2- but, make sure you have a double conductor rated lug for l1.
This way you dont runout of 2p spots, wich will happen real soon with only spot (1) and spot (2) heated up....
Then lay out the 2p first, if that makes sense..
If its a mcp sub, id still take the time to heat up all the terminals.

Edit- ok i see you only need 120 but it is still worth it to heat up every now while you czn, you never know what the future brings! It would be a third less hokey too...imo
 
What size is the breaker to that panel? You stated you only need 40A, with you stating the panel is 700’ feet away, by guessing I would think u would need the wire to be sized accordingly to voltage drop. with the info u are stating, u are losing 27V if the wire to that panel is wired with a 6 AWG, just me guessing.
 
One issue that's been glossed over is that there are only three conductors, so unless the conduit is reliable as an EGC, reconnecting for 120v is the best option.

We still need to know whether the conductors are re-color-able.
 
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