Wire size on 30 amp RV cables

Lots of RV parks have power systems that are not up to snuff for large loads.. kinda like their wifi.

Thanks Guys,
The voltage with no load is 120, drops down to around 115 when the unit starts up and as heat is being produced, it drops to around 111 over a short period of time then stays there. When we park closer to the pedestal, I only use 1 cord and did not notice this happening. leaving for the outer banks this week so I will try with the one cord and see what the drop is. Thanks for all the feedback.

If you're using *both* cords between the power supply and your rig, a 10 volt drop over a run of 50' is not unusual.

Grandpa Joe wrote:
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 on my AC unit with the fan on low speed. Hot water heater was off, no other heavy loads.I do have a surge protector which will disconnect if voltage gets too low.

I suspect the outlet. Worn / loose contacts are probably to blame, more so that the wire in the cord. Repeat your test using a 50a to 30a adapter, as the 50a contacts are a lot beefier and generally used less.

The wire should be #10 in 30 ampere cords.
The problem is likely your heat pump and the other electrical loads.
What is the voltage when the heat pump is not running?
There could be a problem with the heat pump. If you have an Amprobe check what the amperage draw is on the pump and compare it to the specification plate on the unit.

I bet that electric heat really draws the current and is your reason for voltage drop...

When we are using our setup in the cold weather we try to use the 20AMP PEDESTAL service at the camp grounds using a second HD Extension cord running into the trailer to just run our portable electric heaters. This 20AMP service doesn't pull power from the same leg the 30A source is using to feed the trailer.

Helps a bunch for us...

Roy Ken