Identification of ungrounded conductors

Jpflex

Jpflex

Electrician big leagues
Location
Victorville
Occupation
Electrician commercial and residential
If a standard residential single split phase system has a service or pannelboard and if a branch circuit is fed by a 2 pole breaker is it true that each ungrounded conductor per pole would not have to be identified or "phased" per pole?

NEC 210.5 C Makes it appear this way. However when the code says a system with one nominal voltage, does this mean they are only considering the 240 vac pole to pole while ignoring the 120 VAC pole to neutral?

I understand multiple systems with different voltages but what about the above?
 
For a 120/240 volt single phase system there is no requirement to color code which leg an ungrounded conductor is connected to. That's why in almost all residential home dwelling panels you see almost all black conductors regardless of which leg it's connected to.
 
If a dwelling has a PV system with say energy storage is that DC a second nominal voltage or are PV systems exempt?.
 
Jpflex said:
is it true that each ungrounded conductor per pole would not have to be identified or "phased" per pole?
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For discussion lets say a split phase system and a three phase system are present a commercial building, since the split phase is just one phase both wires can be the same color, as voltage and phase are the same.
 
pipe_bender said:
For discussion lets say a split phase system and a three phase system are present a commercial building, since the split phase is just one phase both wires can be the same color, as voltage and phase are the same.
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I thought a 2 pole breaker on a branch circuit even if single phase needed to be identified for its pole to avoid combining these such as at a jbox by someone not aware?
 
don_resqcapt19 said:
It does not say one nominal voltage, it says one nominal voltage system. The nominal voltage system in a typical dwelling is 120/240.
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The wording in nec is ambiguous since a split phase system with a neutral does NOT contain ONE nominal voltage
 
Jpflex said:
I thought a 2 pole breaker on a branch circuit even if single phase needed to be identified for its pole to avoid combining these such as at a jbox by someone not aware?
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If you want to identify the 2-pole conductors to distinguish them, you can, but it is not required.
 
Jpflex said:
The wording in nec is ambiguous since a split phase system with a neutral does NOT contain ONE nominal voltage
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It IS one nominal voltage. The 120V is just leg of the 240V. Both are nominal voltages. Now if you add in 208V, 480V, then you would have more than one nominal voltage. But a 240V/120V is one nominal voltage.
 
don_resqcapt19 said:
It does not say one nominal voltage, it says one nominal voltage system. The nominal voltage system in a typical dwelling is 120/240.
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The wording in nec is ambiguous since a split phase system with a neutral does NOT contain ONE nominal
Little Bill said:
It IS one nominal voltage. The 120V is just leg of the 240V. (((Both are nominal voltages.)))
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Yes as this is my point, the plural voltag(es) you indicate is NOT ONE voltage potential.

The splitting of a single phase system creates two levels of potential or nominal voltage(s). It appears the NEC may have missworded their intention of code.

My other point is that not having wires at opposing poles in a single phase system with different identification or insulation coloring could result in someone unaware combining all same colored or identified wires. This would pose a safety or hazardous concern
 
Article 220 explains the systems


(A) Voltages. Unless other voltages are specified, for purposes
of calculating branch-circuit and feeder loads, nominal
system voltages of 120, 120/240, 208Y/120, 240, 347,
480Y/277, 480, 600Y/347, and 600 volts shall be used.

120/240 is one system as far as the NEC is concerned not to mention the physics of one center tapped winding.
 
When you speak of ONE nominal voltage it could mean either ONE of 115, 120 or 130 VAC being present at a system (system = transformer utilization windings)

this range from 115 to 130 VAC is meant to describe 120 VAC but factors in voltage drop or slightly higher SUPPLY than 120 VAC

I looked in the NEC for nominal voltage definition but i have not yet found it
 
Jpflex said:
I looked in the NEC for nominal voltage definition but i have not yet found it
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Voltage, Nominal. (Nominal Voltage)
A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). (CMP-1)
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However the rule is talking about a nominal voltage system and not a nominal voltage. The voltages of 120 and 240 are nominal voltages found in a 120/240 volt (nominal) system.
 
Jpflex said:
It appears the NEC may have missworded their intention of code.
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If you think that, the system will open for the submission of Public Inputs for 2029 code changes around September 9, 2025.
The use of the word system is intentional and is what the code wanted to say.
 
So in a commercial application... 120/ 208, still nominal as the 120 v is just a leg as said above. If your using all black/ white MC cable 12 awg... We don't usually mark this as its smaller than the minimum size to be marked. Is this correct.
 
I understand the word system is just referring to the type of source transformer with its respective voltage output but what is the ruling on using the same color wire on a 2 pole breaker for a single split phase system?

I have always been shown to wire one black and one red for example. This way wires of the same color but on different poles will not be mixed
 
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