Miswired 3-Phase Pedestals

An update on what I'm working on to demonstrate 3-phase power in campgrounds distributed to single-phase pedestals.

Read my previous article about 3-phase campground power HERE…

Hi Mike!

I read your reply to John Ko: "None of the 50-amp EMS/Surge Protectors actually measure L1 to L2 voltage so they won’t be aware that it’s 3-phase. And your 30-amp shore power connection won’t care at all and will work perfectly. It’s only the maintenance staff that needs to understand it."

But I also read in your article: "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."

So that leaves me wondering, will my Progressive Industries EMS protect my 30 amp RV if I run into a similar incorrectly wired pedestal? - Larry Scofield

Hey Larry,

Yes it will protect your RV from a 3-Phase High-Leg Delta service. I’ve tested both a 30-amp Progressive Industries EMS and a Southwire Total Electrical Protection SurgeGuard under a variety of high-voltage miswiring conditions.

Both Surge Protectors stopped up to 240 volts from getting through to the RV’s 30-Amp shore power inlet. But be aware that a basic ($100) MOV-only surge protector won’t stop high voltage from miswired pedestal outlets since there’s no cutoff relay.

Campgrounds should have 3-phase Wye (Not Delta)

Here’s how it works… Note that with Wye service, you’ll measure 120 volts from any phase to neutral. And between any two phase legs you’ll measure 208 volts. So by treating two of the phase legs like split-phase service, a 3-phase Wye service can be distributed to single-phase pedestals safely. But that’s ONLY if the transformer, service panel and pedestals are wired correctly by properly trained electricians.

Here’s what I’m working on now…

In order to teach RV technicians and campground staff how 3-phase should be wired, I need to show how it works. So I’m dusting off my desktop 3-phase signal generator that can produce 3-phase power in all flavors of Delta, Open-Leg Delta, Grounded-Leg Delta, High-Leg Delta, Wye and Split-Phase at 120, 208, 240, 277 and 480 volts.

Plus, since I’ve recently added a 12-volt 3-phase model airplane motor, I can also demonstrate and discuss phase rotation. Phase rotation isn’t important to RV power. But for any campground with large motors like 3-phase air conditioners for meeting rooms, or 3-phase pumps for water, it’s super important.

Reversing Flux Rotation

Here’s a closeup video of my flux rotation reversal demonstration with a tiny 3-phase motor. Much more on how this works this later, but this is my proof-of-concept video.

Technician training on 3-phase power

So I’m now making a video and seminar showing how an EMS/Advanced Surge Protector can protect an RV from mis-wired High-Leg Delta 120/208/240-Volt pedestals in a campground. I’m being commissioned by PRVCA to create this content for technicians, but I’ll also release it here as well. This is getting interesting!

Let’s play safe out there… Mike