3-phase power in campgrounds!
Campgrounds are now allowed by the NEC to distribute 120/208-volt 3-phase power directly to pedestals… What could possibly go wrong?
Very few campground and RV technicians understand anything about 3-phase electrical service, yet new campgrounds are beginning to distribute 3-phase power directly to standard split-phase pedestals.
3-phase power can be tricky
This is a recipe for disaster if the campground maintenance staff doesn’t understand how various 3-phase services work. In fact I know of one campground in Texas that tied a bunch of new pedestals int!o a High-Leg Delta panel without measuring the voltage on the “Wild Leg”. They ended up sending 208 Volts to half a dozen 30-amp TT-30 pedestals, which burned up the electrical systems in several RV trailers before someone metered it. They thought it was lightning strikes at first. Nope, it was not understanding High-Leg Delta Service.
I know a lot about 3-phase power
I happen to have a 50-year background in 3-phase industrial and concert generator power, and built my own 3-phase signal generator for training Audio and Lighting technicians. Yes it’s a little bit Frankenstein, but being able to demonstrate all these different 3-phase services really helped my diagnostic abilities. I learned a lot once I could see it all up close and personal.
Enter the FunkWorks Lab!
This table-top signal generator I built can create a low-power 3-phase service in all configurations including 120/208-Volt Wye, as well as 120/208/240/277/480-Volt Delta, Grounded-Leg Delta, Open-Leg Delta, and High-Leg Delta. It can even create foreign electrical services such as 50 Hz single-leg UK power or 100 Volt Japanese power.
High-Leg Delta Service can be confusing…
This type of 3-phase service was really common in the 1960’s for industrial plants that needed a lot of 208-Volt 3-phase power for electric motors, but also required split-phase 120/240-volt power for the offices. Plus it needs one less transformer from the power company to make it work. I’ve seen it in dozens of old industrial buildings that were later converted into office space. And at least a few campgrounds had High-Leg Delta Service for some unknown reason!
What I want to teach
My plan is to offer a basic 3-phase power course to RV technicians and campground electricians who may encounter 3-phase electrical service in the wild. I’m not going to teach all the design elements needed to install a full campground power distro system. But at the very least anyone working on 3-P service should be aware of how to measure it. This isn’t really that difficult to understand once you get your head wrapped around the concepts, and my 3-Phase signal generator with a 4-channel digital oscilloscope is the perfect demonstration tool. Note that I can display a live video of the separate 3 phases in real time on a video projector or television. It’s a geek’s dream come true!
Please let me know if you’ve encountered a 3-phase service in campgrounds during your travels. The hint is the power measures 120-Volts hot-leg to neutral, and 208-Volts leg-to-leg.
And if you have a campground wired with 3-phase power and want to train your maintenance staff on how it all works, I’m your guy…
It’s perfectly safe to plug your RV into a pedestal that’s wired with 3-phase service, as long as the campground wired it correctly.
3-Phase power in the campgrounds can be a good thing because there are advantages. Limiting the installations to only 120/208 Wye systems would make it easier to understand resulting in a safer environment.