RVelectricity – Low Voltage Report
Since the Stray Voltage Patrol is already generating some interesting reports, I’m going to use one of them to discuss the problem of low voltage in campgrounds, especially state owned and operated parks. Here’s what part of an SVP report looks like:
What did you discover? Pedestal voltage measured too low (below 104 volts)
Describe what you discovered: Voltage 117 with about 10% of sites filled, but got down to 93 Volts with 85% of sites filled. Very time-of-day dependent as campers turned on AC or cooking loads, but voltage in the 90s is terrible sag!
Number of campsites tested: 4
Name of campground: Willow Bay Recreation Area
Campground owner name: PA State Park
What are the basics? Well, it’s simple. The electrical distribution grid powering this campground wasn’t designed with enough capacity to provide a full campground with stable electrical power. There’s a variety of specific design flaws that could be suspect, but I’m guessing it might be the main power company line transformers being of insufficient size to power the entire campground when everyone is running their air conditioners at the same time. While the power company can, in fact, change the taps on the incoming transformers to boost the voltage a bit, that 117 volts is actually very close to the NEC (National Electrical Code) design specs. In fact, I’ll bet that if you turned off EVERYTHING in the park, the voltage would bump up to 120 volts.
So is this bad? In a word, yes. Now, it’s not likely to cause a hot-skin/stray-voltage, nor is it likely to start a fire in your RV. However, it’s very likely to cause many RV air conditioners to either not start or even burn out. Residential refrigerators in the RVs will also have the same sort of issues. Compressor motors tend to be very amperage hungry during startup, and rely on a stable 120-volt power source to get up to speed quickly. I’ve often said that anything below 100 volts can be damaging, and here we have an example of 93 volts. So, use at your own risk since I don’t think the state park is going to pay for your new air conditioner or refrigerator.
Is there a quick fix? Now the inevitable questions about Hughes AutoFormers will start coming in. And while an auto-boost transformer could increase the voltage at a single campsite, it will be stealing even more voltage from the campsites around it. Don’t believe the marketing hype on the Hughes website. A booster transformer can’t restore full wattage (power) to a campsite. It can only restore full voltage by essentially stealing it from other campsite pedestals in the area. That’s why the 2020 version of the National Electrical Code will likely prohibit booster transformers in campgrounds.
Why does this happen? It’s also possible that the branch circuits in the park weren’t designed with heavy enough electric wiring for the length of run between campsites. For example, if you run a 10-gauge/30-amp extension cord 25 feet you might experience 2 volts of drop under full load. But run a 10-gauge branch circuit 200 feet (8 times as far), and the voltage drop under full load will be increased to perhaps 8 x 2 volts = 16 volts. Starting with 120 volts at the distribution point, we can subtract that 16-volt drop and end up with only 104 volts at the pedestal. And that’s just for ONE campsite that’s running their air conditioner. Multiply that by dozens or even hundreds of RV air conditioners at a campground, and you’ll see just how and why 93 volts is possible. Yikes!
Is this an expensive fix? Well, it sounds like either the incoming power company transformers are out of capacity, so the power company will need to upgrade to larger KVA units, or the underground wiring is too small for the lengths of run they have to do, so the old wiring will need to be dug up and rerun with heavier gauge copper wire. Both options are expensive, which will have to be passed on to the consumer, either by taxes and increased registration fees for the state-run parks, or increased day rates for privately owned campgrounds. Running new electrical distribution isn’t cheap, but it’s probably the only way many parks like this can get their power up to acceptable levels.
Please answer in the comment section below about any state parks or private campgrounds you’ve found that have low voltage. It appears to be a major problem in many campgrounds.
Let’s play safe out there….