1 phase 4 wire

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profT

Member
Location
IN
Hi again guys,

This forum is pretty helpful but I think I am just not using the right keywords in the search bar:dunce:

I was curious to know how is a 4 wire aluminum service cable (2-2-2-4) generally run into a load center if its only one phase? Feel like its something obvious I'm missing here.

More info: I'm talking about the service cable running from a main disconnect to a sub panel which would be using 2-2-2-4

Thanks as always.
 

MAC702

Senior Member
Location
Clark County, NV
Hot #1 (120V to neutral/ground)
Hot #2 (-120V to neutral/ground, relative to the other hot, so 240V to the other hot)
Neutral
Ground

The "single phase" is that there is only one hot-to-hot possibility.
 

Carultch

Senior Member
Location
Massachusetts
Hi again guys,

This forum is pretty helpful but I think I am just not using the right keywords in the search bar:dunce:

I was curious to know how is a 4 wire aluminum service cable (2-2-2-4) generally run into a load center if its only one phase? Feel like its something obvious I'm missing here.

More info: I'm talking about the service cable running from a main disconnect to a sub panel which would be using 2-2-2-4

Thanks as always.

Single phase commonly means split phase. Line 1 is 120V phase-to-neutral, line 2 is as well, except the mirror image of that. Line 1 to line 2 is 240V. There are three current-carrying conductors, which are line 1, line 2, and neutral. The fourth wire is the equipment grounding conductor, which has the purpose of establishing electrical continuity among non-electrical metal (enclosure walls, conduit, building steel, etc). When it is on the utility side of the main service disconnect, the neutral/EGC can be combined. When it is on the load side, the neutral and EGC are separate conductors.

Now you might think that this looks like line 1 and line 2 are two phases, that are 180 degrees out of phase. And I would agree. It is two sine waves that are 180 degrees out of phase. Why then do we call it single phase, you might ask? The reason is that when it comes from 3-phase transmission or distribution, it is derived from just one of the transformer phase coils. Your neighbors, or other neighborhoods, have the remaining phases to derive their single phase systems. The secondary side coil of the single phase transformer is split in the center, where the neutral is connected. The two lines are connected to opposite ends.
 
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profT

Member
Location
IN
I think I understand you guys, but by any chance does anyone have a diagram? From what I understood the two hits go where they would be normally, the neutral/ground as well, except if add one more wire to the neutral/ground anywhere else on the panel. Does that sound correct?
 

jumper

Senior Member
I think I understand you guys, but by any chance does anyone have a diagram? From what I understood the two hits go where they would be normally, the neutral/ground as well, except if add one more wire to the neutral/ground anywhere else on the panel. Does that sound correct?

Profit, this seems to be going DIY and that is against forum rules.

Is this a home project? your electrician should know this info.
 

Carultch

Senior Member
Location
Massachusetts
I think I understand you guys, but by any chance does anyone have a diagram? From what I understood the two hits go where they would be normally, the neutral/ground as well, except if add one more wire to the neutral/ground anywhere else on the panel. Does that sound correct?

The two hots, usually marked red and black, connect to the breaker terminals busbars.
The neutral connects to a busbar that is insulated from the panelboard enclosure.
The ground connects to a busbar that is bonded to the panelboard enclosure, and bonded to every other piece of inactive metal in the system

Neutral and ground can only be joined on the line side of the service disconnect. On the load side, they are kept separate.
VTifb.png
 
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Carultch

Senior Member
Location
Massachusetts
uh oh, the wording in that note about phase will cause this thread into a plus 300 post tangent.:D

Well it is two voltages sine waves that have their rising zero crossings at two different points in time. L1 voltage rises through zero at t=0, while L2's voltage rises through zero at t = 1/2 cycle. So not knowing the physical construction of how it is made, makes it looks like it is two phases. Someone who defines the word phase as the cycle offset in a wave, would call the lines phases and think nothing of it. In reality, it comes from one phase that is centertapped to make both 120V and 240V be present, so split-phase is my preferred term for it.
 
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GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
One way of looking at it, including from the linear algebra (vector math) point of view is this:

Once you define a reference phase (often the voltage waveform when describing phas of current) you can express the phase of a sine wave by a phase angles.
If you have two truly different phase angles, you can add them, with different numerical amplitudes, to produce a vector (or phasor) with any arbitrary phase angles.
This is true for two phase, three phase, n-phase. And regardless of the number of phases you need only any two to produce any arbitrary phase angles.
When you look at 120-0-120, you find that no matter how you combine L1 and L2, with transformers and voltage dividers, you get only more or less amplitude of the same phase angle. Hence, "single phase".

Sent from my XT1585 using Tapatalk
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Wow !
"what time is it ?"
"Here, let me show you how to build a watch !"
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Thread certainly appears to be DYI in nature; therefore:
I am closing this thread, in accordance with the Forum rules. This Forum is intended to assist professional electricians, inspectors, engineers, and other members of the electrical industry in the performance of their job-related tasks. However, if you are not an electrician or an electrical contractor, then we are not permitted to help you perform your own electrical installation work.


If I have misjudged the situation, if for example this project is related to your work, then send me a Private Message. If you can show me that I am wrong, and that you are a licensed electrician (or at least a licensed apprentice), then I will reopen your post, and offer an apology for the delay and inconvenience.
 
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