# Calculating Voltage Drop for an Underground Circuit

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Determining Voltage Drop for an Underground Circuit
Background: John, a Homeowner from Forrest hills, NY

Question: I’m installing two 110v line at 20amps, at three hundred feet is # 6 THHN enough or should it be # 6 THWN this run is under ground in PVC.

Thanks for your electrical question John.
When installing wire in underground PVC conduit use THWN, not THHN.
Please see the link below to calculate the wire size for running the circuit 300 feet so you can factor in voltage drop.

I have provided the following links that lead to fully detailed information on this website that will assist you with your electrical question:

Electrical Calculations and Formulas

Electrical Wiring