Wire size on 30 amp RV cables
Do the commercial 30 amp RV cables you purchase from Camping World, Walmart, etc use #10 gage wire or larger? I have 2 of these, both 25 feet long and noticed a 10 volt drop when running the heat pump...
Forum Discussion
For future reference, the math behind tenbear's post :)
Voltage drop formula: V=IR
10ga wire is 3.4 ohms per kilometer, 100 feet (50 feet * 2 conductors) is (rounded up) 31 meters
31/1000 = 0.031 * 3.4 = 0.11 ohms for the 100 foot of conductor (rounded up).
30a * 0.11 ohms = 3.3 volts ...
a drop of more than 3v from one end of the cable to the other indicates it's overloaded, damaged, or it's not really using 10 gauge conductors...
12 gauge; 5.4 ohms per kilometer = 0.031 * 5.4 = 0.17 * 30 = 5.1 volts
14 gauge; 8.54 ohms per kilo = 0.031 * 8.54 = 0.27 * 30 = 8.1 volts
the scary part:
P=V*I ... 3.3 * 30 = 99 watts ... good reason to not coil up shore power cords, 100 watts of heat is no small matter.
Voltage drop formula: V=IR
10ga wire is 3.4 ohms per kilometer, 100 feet (50 feet * 2 conductors) is (rounded up) 31 meters
31/1000 = 0.031 * 3.4 = 0.11 ohms for the 100 foot of conductor (rounded up).
30a * 0.11 ohms = 3.3 volts ...
a drop of more than 3v from one end of the cable to the other indicates it's overloaded, damaged, or it's not really using 10 gauge conductors...
12 gauge; 5.4 ohms per kilometer = 0.031 * 5.4 = 0.17 * 30 = 5.1 volts
14 gauge; 8.54 ohms per kilo = 0.031 * 8.54 = 0.27 * 30 = 8.1 volts
the scary part:
P=V*I ... 3.3 * 30 = 99 watts ... good reason to not coil up shore power cords, 100 watts of heat is no small matter.
