NEC Table 9

[nightfox1925]

Table 9 of the NEC are having Line-to-Neutral Ohms values. This being used in the Vdrop formula (without root of 3), I will get the Line-To-Neutral Vdrop. Adding the root of 3 to the equation will give me the Vdrop line-to-line.

If I have 1)three phase branch load and 2)single phase branch loads connected line-to-line and 3)single phase loads connected line-neutral,is the calculation of the Vdrop gonna be the following using NEC table 9:

1)3Ph Vdrop = 1.732*L*3Ph current*[R*PF + X*sin(arcosPF)]

2)L-L Vdrop = L*(L-L 1Ph current)*[R*PF + X*sin(arcosPF)]

3)L-N Vdrop = L*(L-N 1Ph current)*[R*PF + X*sin(arcosPF)]

Thanks

 

[jghrist]

If you have a mix of line-to-line and line-to-neutral connected loads and all of the phases are not balanced with each, the voltage drop becomes complicated and the simplified formulas do not work. This is because the current angles of line-to-line and line-to-neutral connected loads are different even if the power factor is the same.

The simplest way to get a conservative estimate of voltage drop is to assume all loads are balanced with each phase having the maximum of the actual phase load.