multiwire branch circuts / follow up.

[automate0042]

Yes, that is what I was trying to state- if the original post were to be connected to 1 ph supply, then the imbalance amps would be 0. I was trying to figure out if the formula presented subsequently was "generic" or was it specific to the original post's supply, i.e it takes into account the 120 deg shift line to line, Y connection etc. i may have injected a confusion factor when i referenced a single phase system.

 

[George Stolz]

I was viewing this from an "imbalance perspective". where if connected to a 1 ph multiwire branch ckt, vectorly the neutral amps would be 0, would it not?

To be clear, in my picture there are six amps flowing from A to Neutral, and five amps flowing from B to neutral, so in a single phase system the neutral current would be one amp. In a 208Y/120 system, there would be 5.56 amps flowing on the neutral.

Think of the three circles in my drawing as being three teams of people, say 100 people in each team. The "A" team has 50 individuals who want to run to "C", and 50 who want to run to "B". When the load establishes a path between the "A" team and the neutral, then the teams go where they want to go, using the neutral connection as a path, or bridge.

Coincidentally, the path from "B" to neutral is available at the same time in the picture.

Due to the resistance of the load (the width of the path), only six individuals are walking between "A" and "N". Only five are walking between "B" and "N".

In the picture, only the members of "A" team that want to go to "B" move, because the ones that want to go to "C" are waiting for their path to do so.

This is how I picture it, as goofy as it may sound.

 

[roger]

Yes, that is what I was trying to state- if the original post were to be connected to 1 ph supply, then the imbalance amps would be 0.

There would not be an imbalance, it would be balanced. Any time the loads are equal in a single phase MWBC there will be zero amps flowing on the neutral.

Roger

 

[automate0042]

A matter of semantics? Thank you, that is what was trying to say with my own brand of terminology- The imbalance current is zero- no imbalance amps.

 

[roger]

A matter of semantics? Thank you, that is what was trying to say with my own brand of terminology- The imbalance current is zero- no imbalance amps.

No, it is not semantics, it will either be balanced or an imbalanced, they are not the same and the neutral load will reflect this, see the diagrams below


An unbalanced or imbalanced neutral load.

A balanced neutral load

Roger

 

[automate0042]

I'm sorry for the confusion- I realize that X amps flowing "left" and X amps flowing "right" makes a balanced neutral- I guess that I have always looked at that condition as having an imbalance current of 0, X-X=0, no imbalance. I'm still trying to hear in my head why "imbalanced currentof 0" would be incorrect terminology where the neutral current is balanced. I'm assuming that imbalance means not balanced.