That tingle is electricity in the water, and it’s the warning sign of electric shock drowning. It kills swimmers every year, most often at freshwater lakes just like Keowee, Hartwell, and Jocassee. Get out, stop swimming there, and get it tested. I measure it, document it, and fix it.
Electric shock drowning happens when low-level current passes through the water and through a swimmer’s body. In freshwater, your body conducts better than the water around it, so the current goes through you. Even 2 to 3 volts in the water can be felt as a tingle, and current around 10 to 15 milliamps can paralyze your muscles. A swimmer who can’t swim, drowns. You cannot see, hear, or smell electrified water. The only warnings are a tingle, or a measurement.
Where does the voltage come from? The utility grid uses a multi-grounded neutral: the same neutral wire that carries return current for the whole neighborhood is grounded at pole after pole, and at every house. When that neutral carries current, which it always does, a small voltage develops between the grounding network and the true earth. That’s neutral-to-earth voltage, NEV, sometimes called stray voltage. The electrical code requires every metal part of your dock to be bonded to the grounding system, for good fault-safety reasons. So your dock frame inherits whatever voltage is on that network, and a swimmer touching the ladder becomes the connection between the two.
Dock frame to water, with the entire house main breaker OFF
At a neighboring property, with every breaker in the building off
The home’s grounding system above true earth, main disconnect open
A Lake Keowee homeowner called us after feeling tingling near their aluminum dock. Most electricians would check the dock wiring, find a fault, fix it, done. This one was different, and it’s the reason this page exists.
We measured 1.7 to 1.8 volts between the metal dock frame and the water. The voltage stayed with the branch breaker off. It stayed with the entire house main breaker off. It only disappeared when the dock was physically unplugged, hot, neutral, and ground all disconnected. The GFCI protecting the dock never tripped, and never would, because this current doesn’t pass through the GFCI’s sensor at all.
We then tested neighboring properties and found the same condition. Using an independent ground rod at the shoreline, connected to nothing, we measured the home’s entire grounding system sitting roughly 2.7 to 2.8 volts above true earth, with the main disconnect open. When voltage is present with all customer power off, the customer’s wiring is not the source. The voltage is arriving from the utility grid itself.
Every piece of metal a person can touch, frame, ladders, gangway, rails, gets bonded together with solid copper so it all sits at the same potential. No voltage difference means no current through a body. During verification we found an unbonded framing section reading 1.4 volts right beside the swim ladder. Invisible to the eye, found only by testing. Moving joints get flexible bonding jumpers, because moving metal never bonds itself.
A properly driven ground rod at the water’s edge, bonded to the dock frame and the grounding conductor, references the dock to local earth. On one property this took the frame-to-water reading from 3.5 volts down to 0.7, measured before and after with power on. An isolated rod that isn’t tied back into the grounding system is worse than none. We found one of those too.
GFCI protection at the panel, not just a receptacle at the dock. Receptacle GFCIs corrode and fail at the waterfront, and we’ve found them deliberately jumpered out after nuisance trips. A breaker in the house panel protects the whole feeder and can’t be bypassed with a screwdriver.
The code requires permanent signage, WARNING: POTENTIAL SHOCK HAZARD, ELECTRICAL CURRENTS MAY BE PRESENT IN THE WATER, and an emergency disconnect within sight of the dock so anyone can kill power instantly.
NEV rides in on the utility’s neutral and ground connection, so the complete solution is to break that metallic connection with a UL-listed shielded isolation transformer. The dock becomes its own electrical system, referenced to the shoreline ground rod, with GFCI on the output. The utility’s voltage physically cannot cross it. No resets after outages, no maintenance, decades of service life.
We documented every reading, multiple properties, timestamps, main-off tests, independent-earth references, and brought the case to Duke Energy. Their written response is candid in places. It acknowledges that their multi-grounded neutral design can develop NEV, walks through why a few volts can drown a swimmer, and then concludes that a safe dock electrical supply “is the responsibility of the customer.”
We don’t fully agree with that last part. Utility-side repairs genuinely reduce NEV, and we keep pursuing source-side correction for our clients. But the practical takeaway for homeowners is this: the customer-side protections above are what stand between your family and the water, and they work. We proved it with a meter, before and after, at every step.
Duke Energy’s customer letter on electrical shock around docks and piers, retyped for legibility by Sunset Electric. The original is available on request.
If any of these sound familiar, nobody swims until it’s tested. Testing is fast, non-invasive, and definitive.
Any tingling sensation in the water, on the swim ladder, or on metal dock parts. That’s current, and it’s the only warning you get before the water itself.
Dogs that hesitate at the dock or won’t get in near it are often feeling what you can’t. Take it seriously.
So-called nuisance trips are often real leakage current. A GFCI that keeps tripping is telling you something is wrong, not that it’s broken.
A GFCI that’s been jumpered out after it kept tripping is an emergency, not a fix. We’ve found them on this lake.
No GFCI protection, no signage, wiring of unknown age. Docks built before the current code cycles are missing protections that exist for exactly this hazard.
An isolated rod at the dock that isn’t tied back into the grounding system removes the fault-clearing path. It’s worse than no rod at all.
Have a question not listed here? Call or text (864) 436-8680 — I’m happy to talk through it.
One visit: documented readings, a straight answer on whether the source is your wiring or the utility, and the fix, priced before I start.
Mon–Fri · 8am–6pm · Same-day emergency service available
If you feel tingling in the water: get out immediately, staying low and swimming away from the dock. Do not touch metal on your way out. Keep everyone out of the water and call a licensed electrician.