Difference between one-line & two-line diagrams

[ssabbagh]

I need a clear description of what is meant by One-line representation of an electrical power and/or circuit.
Also what is the difference between one-line & two-line diagrams?

 

[controlsdude]

one line is showing the 3 phase power as one line on an electrical diagram, versus showing each phase as a line between devices. I believe most diagrams show the one line = 1L1,1L2,1L3, etc

two line diagram typical shows the left side as hot running from top to bottom and the neutral or common side on the right side. Then all your devices that are wired in between these two rails.

 

[ssabbagh]

Thanks a lot. However, I cannot understand the two line diagram. I don't know what you mean by "Hot running from top to bottom". Could you provide a reference for this?

 

[controlsdude]

Hot = 120VAC, 24VDC, or any control voltage
neutral or commom = 120vac neutral or dc com

see attachment, its an example

picture worth a thousand words

I believe also that NFPA70 has examples of these diagrams in their document.

 

[danw2]