George3037 wrote:
I just installed a 30A plug for my TT about 3 weeks ago. I used 10 ga. direct burial underground wire inside 3/4" PVC conduit. Ran 50' from post to house and 50' through basement to a 30A breaker in the breaker box in garage. Voltage drop is acceptable.
I measured 121.5 at the breaker and 120.4 at the plug with no load. That's less than the 5% drop I expected.
Measured 119.9 at the trailer end with fridge running, some lights and a TV on. Kicked on the A/C with the above and it measured 113.6V which is about 8% drop under load but acceptable to me.
Total cost was about $450. All materials were bought at HD.
Under no load, the expected voltage drop is zero. (Recall Ohm's law: V = I * R. No load means that the current I is zero, and so the voltage across the resistance--the voltage drop--is also zero.) Maybe the line voltage fluctuated while you were making your measurements, or maybe there was a load you weren't considering such as the converter charging batteries.
At any rate, it seems to be okayish for what you need, so there's no need to speculate on what was going on.
Edit: Just noticed the 20A outlet there. Is that on the same 30A circuit (without a 15 or 20A breaker protecting it)? If so, that's definitely not up to code and a bit of a concern; the receptacle is underrated for the circuit's ampacity.
