omerzia
Member
- Location
- New York, USA
I have a circuit with (3) parallel branches. How do i calculate the total voltage drop on the circuit?
Total Voltage Drop
- Thread starter omerzia
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
The main part of the branch circuit will carry the load of the 3 branched areas. Calculate that and the add the greatest vd of the 3 branches
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Tell us more about the situation.
Are you talking about finding the voltage drop on the common portion of a circuit that branches three ways downstream? Or are you trying to find the voltage drop on the parallel portions themselves?
JFletcher
Senior Member
- Location
- Williamsburg, VA
Welcome to the forum.
Voltage drop depends on load, and the length and the size of the wiring. If you plug in a 9W LED light at the end of a short 120V circuit, you may not see a 1/10th of a volt drop. A vacuum cleaning trying to eat a rug on the same circuit could cause a 20+V drop
There are posted tables of resistance values for all wire. Or instead of calculating it you can measure it directly.
What Dennis wrote for your avg house circuit. The parallel portions can be ignored since the wiring itself is not in parallel between source and load.
For parallel resistance calculations, it' s 1/Rt = 1/Ra + 1/Rb +1/Rc, where Rt is total resistance and a,b, and c are the resistances of the parallel branches.
https://www.swtc.edu/Ag_Power/electrical/lecture/parallel_circuits.htm
Voltage drop depends on load, and the length and the size of the wiring. If you plug in a 9W LED light at the end of a short 120V circuit, you may not see a 1/10th of a volt drop. A vacuum cleaning trying to eat a rug on the same circuit could cause a 20+V drop
There are posted tables of resistance values for all wire. Or instead of calculating it you can measure it directly.
What Dennis wrote for your avg house circuit. The parallel portions can be ignored since the wiring itself is not in parallel between source and load.
For parallel resistance calculations, it' s 1/Rt = 1/Ra + 1/Rb +1/Rc, where Rt is total resistance and a,b, and c are the resistances of the parallel branches.
https://www.swtc.edu/Ag_Power/electrical/lecture/parallel_circuits.htm
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