Single phase panel improperly wired as 3 phase

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mike1061

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Chicago
I got a defect notice, "Service improperly wired as 3 phase branch circuitry on single phase"
What it refers to, is the use of Black, Red and Blue colored wires used as ungrounded conductors for branch circuits. It's a single phase residential service. He was saying that I should have used only Black and Red.

I thought this was ok to use all three colors. I've also done this for 95% of the jobs I've done. Nobody has ever said anything.

Thanks
Mike
 
AFAIK you should be okay. It is when you have two or more nominal voltages in 1 building, ie: 208/120 and 480/277, that you have to identify which system is which.

210.5 Identification for Branch Circuits.

(C) Ungrounded Conductors. Where the premises wiring
system has branch circuits supplied from more than one
nominal voltage system, each ungrounded conductor of a
branch circuit shall be identified by phase or line and system
at all termination, connection, and splice points. The
means of identification shall be permitted to be by separate
color coding, marking tape, tagging, or other approved
means. The method utilized for conductors originating
within each branch-circuit panelboard or similar branchcircuit
distribution equipment shall be documented in a
manner that is readily available or shall be permanently
posted at each branch-circuit panelboard or similar branchcircuit
distribution equipment.
 
in resi, you can use any color you want for ungrounded - except for green, white and grey. I have used black, red, blue, brown, orange, yellow and violet in residential.

~Matt
 
I don't see a problem with using black, red, and blue unless you used a 4 wire MWBC. Then you would have a problem with two hots on the same leg.
 
mike1061 said:
I got a defect notice, "Service improperly wired as 3 phase branch circuitry on single phase"
What it refers to, is the use of Black, Red and Blue colored wires used as ungrounded conductors for branch circuits. It's a single phase residential service. He was saying that I should have used only Black and Red.

I thought this was ok to use all three colors. I've also done this for 95% of the jobs I've done. Nobody has ever said anything.

Thanks
Mike
Click to expand...

WAIT A MINUTE EVERYBODY!! Look at the OP. Mike, are you saying that you use the black, red AND blue? If you are using 12/4 cable (3 phases & 1 neutral) connected to a single phase panel, then you are overloading the neutral and the inspector is correct! If this is the case and you have done 95% of your jobs this way, you'd better add some additional coverage to your liability insurance!
 
Split Bolt said:
If you are using 12/4 cable (3 phases & 1 neutral) connected to a single phase panel, then you are overloading the neutral
Click to expand...

1) Who says it is not pipe and wire?

2) Not 'you are' overloading the neutral, more like 'in an extreme condition you might actually run the neutral a bit warm.'
 
iwire said:
1) Who says it is not pipe and wire?

2) Not 'you are' overloading the neutral, more like 'in an extreme condition you might actually run the neutral a bit warm.'
Click to expand...

1) No one says it's not pipe and wire, that's why I asked!

2) There is the potential to overload the neutral. Are you suggesting that it is OK to do this because the chances of this "extreme condition" occurring are small?
 
I also say that you cannot have 3 hot conductors with one neutral on a single phase service, however if the neutral were sized for 40 amps you probably can get away with it. Seriously, most inspectors probably won't go for that either so--- 2 hots to one neutral. On a 3 phase system you can have 3 hot conductors to one neutral.
 
Dennis Alwon said:
I also say that you cannot have 3 hot conductors with one neutral on a single phase service, however if the neutral were sized for 40 amps you probably can get away with it. Seriously, most inspectors probably won't go for that either so--- 2 hots to one neutral. On a 3 phase system you can have 3 hot conductors to one neutral.
Click to expand...

On a single phase, or three phase, you can have as many ungrounded as your heart desires per grounded conductor, as long as properly sized
 
Hey Bob, Sorry I ran away this morning, I had to go to work! Maybe it is an exaggeration to say this will catch fire or something, but here's how I look at it: Let's say that 12-4 cable was used to run 3 circuits from a single-phase residential panel. (as the name of the thread implies) And let's say the 3 circuits were split-up in such a way that all three went to bathroom receptacles in a large house. The black run (on A phase) goes to the mother's bathroom plug, the red run (on B phase) goes to the father's bathroom plug and the blue run (on A phase) goes to both of the two daughter's bedrooms. Everybody is getting ready to go out at the same time. Mom has her 1875W hair dryer going and the 95W curling iron warming up. (total of 1970W, or 16.4A) Dad's got nothing electrical going on. One of the two daughters has her 1500W hair dryer going and the other has her 1000W hair dryer/curler thingie going. (their total is 2500W, or 20.8 amps) [we all know that a $3.50 breaker is not calibrated that well and will hold this load!] This brings the total load on A phase (black & blue) to 4470W or 37.25A and B phase (red) has no load. That means that the #12 neutral is carrying 37.25A back to the panel! "A bit warm" you say? I say it could create enough heat to start a fire somewhere along the run! Far fetched? I'll give you that! Possible? You be the judge! As someone who has sat on the witness stand in the civil case of a house that burned down from an electrical fire, I say it's not worth taking the chance! (The company I worked for was correctly found "not liable" for that fire by the jury, by the way!)

FPN: The above wattage ratings are real. (I ran over to my wife's side of the bathroom 3 times during the writing of this post!):D
 
I believe SF will only accept black and red for single phase installations. Maybe Mark or one of the other SF locals can verify this.
 
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