- Jan 7, 2007
- 907
- Boat Info
- 2006 52SB, Ray Marine E120, Garmin 7612 through BOE site sponsor,
- Engines
- QSM11s
I’ve have copied this from an AGLCA (America’s Great Loop Cruising Association) I read & review Daily. We completed our first Loop in 2015/16 and became a Life Member as I’ve learned so much from the posting since 2014. Im sure the posted would be more than happy to share this story as it is a learning moment that we all can benefit from.
“Interesting day today on the Erie Canal. Sanctuary and crew are on the wall at Hurst Harbor in Waterford, NY. Behind us on the dock was a young couple on a sailing catamaran who are home schooling two children while cruising. They have an adorable Dalmatian puppy; just beginning to get her spots. So, they were out playing with the pup with a tennis ball. The pup was full of energy. Fast and fun! The family was having a ball. Predictably, there came a time when the ball went into the water. Dad rushed down the dock to retrieve the ball.
What happened next was anything but predictable. He reached into the water and jumped back as if he'd seen a hungry alligator coming at him. He said he'd gotten a whopping bad electric shock. I grabbed my breakout cords and installed them in both of my 30A shore power cords. On the ground conductor, I was expecting to see lots of power flowing to ground, but all I measured was 3 mA. Clearly, there was no power in the water trying to get back to shore via my boat. So we took the breakout cords to the family's catamaran. Again, no power in the water, so no current flowing in the ground conductor.
About this time the caretaker of the property comes along with a digital voltmeter. We went to where dad says he got shocked. We put one lead of the DVM on the surface of the rain-soaked wooden dock, and we dipped the other lead of DVM into the water. The DVM measured 60 volts of AC. After some probing along the linear face of the dock, we discovered that there was a voltage along about 50 feet of the dock. In the center of the field, we measured 65 volts. Out towards the edges, the field dropped down to zero. Predictable pattern for fresh water.
The water here is fresh water, coming down from the Waterford flight of locks from the Mohawk River water shed. We had two inches of rain last night, so the wooden planks of the dock were thoroughly soaked,. The caretaker went off to disconnect power to the feeder. Sure enough, the field in the water went right away. Turning that breaker back on, the field was immediately back.
They immediately shut down that feeder while they schedule repairs, and the caretaker measured the rest of the docks. No further problems were identified.
Consider the worst case scenario that could have been... The tennis ball goes into the water, the puppy follows the ball, and dad follows the pup. Now there are two living beings in the water. No one is yet the wiser, because there is no power in the actual water. But as soon as dad touches that dock trying to get out, he's toast. He can't get out of the water, and he can't let go.
What was the fault? Don't know. Leaving tomorrow morning, so will probably never know. Maybe a nail through the feeder, maybe a chafed wire, who knows? Would a ground fault sensor at the head of the feeder have disconnected this fault? Yes, as soon as dad touched the dock trying to get out of the water. Would a ground fault sensor at the pedestal have tripped off power? No, the fault was in the feeder, not one of the boats connected to the feeder. The dock itself was energized: "hot." This facility is not "compliant" with the NEC, Article 555.
The lessons here are obvious. Thankfully, no one was actually hurt. But think of all the posts we've had over the past few years about ground fault sensors. This is why the NEC requires them. We were all walking on a "hot" dock. With grounded metal brackets holding the dock to the wall. We were all oblivious to the risk until that tennis ball went int the water and dad laid on the dock to retrieve it. Had the ball not gone into the water, just imagine what worse event could have exposed that risk?
I felt good that I could explain to the caretaker what was happening. I feel blessed that no one - not the dad and not the pup - was hurt. NEVER SWIM IN A MARINA OR AT A DOCK WITH POWER! NEVER!”
Jim
Monk 36 Hull #132
MMSI #367042570
AGLCA #3767
MTOA #3436
“Interesting day today on the Erie Canal. Sanctuary and crew are on the wall at Hurst Harbor in Waterford, NY. Behind us on the dock was a young couple on a sailing catamaran who are home schooling two children while cruising. They have an adorable Dalmatian puppy; just beginning to get her spots. So, they were out playing with the pup with a tennis ball. The pup was full of energy. Fast and fun! The family was having a ball. Predictably, there came a time when the ball went into the water. Dad rushed down the dock to retrieve the ball.
What happened next was anything but predictable. He reached into the water and jumped back as if he'd seen a hungry alligator coming at him. He said he'd gotten a whopping bad electric shock. I grabbed my breakout cords and installed them in both of my 30A shore power cords. On the ground conductor, I was expecting to see lots of power flowing to ground, but all I measured was 3 mA. Clearly, there was no power in the water trying to get back to shore via my boat. So we took the breakout cords to the family's catamaran. Again, no power in the water, so no current flowing in the ground conductor.
About this time the caretaker of the property comes along with a digital voltmeter. We went to where dad says he got shocked. We put one lead of the DVM on the surface of the rain-soaked wooden dock, and we dipped the other lead of DVM into the water. The DVM measured 60 volts of AC. After some probing along the linear face of the dock, we discovered that there was a voltage along about 50 feet of the dock. In the center of the field, we measured 65 volts. Out towards the edges, the field dropped down to zero. Predictable pattern for fresh water.
The water here is fresh water, coming down from the Waterford flight of locks from the Mohawk River water shed. We had two inches of rain last night, so the wooden planks of the dock were thoroughly soaked,. The caretaker went off to disconnect power to the feeder. Sure enough, the field in the water went right away. Turning that breaker back on, the field was immediately back.
They immediately shut down that feeder while they schedule repairs, and the caretaker measured the rest of the docks. No further problems were identified.
Consider the worst case scenario that could have been... The tennis ball goes into the water, the puppy follows the ball, and dad follows the pup. Now there are two living beings in the water. No one is yet the wiser, because there is no power in the actual water. But as soon as dad touches that dock trying to get out, he's toast. He can't get out of the water, and he can't let go.
What was the fault? Don't know. Leaving tomorrow morning, so will probably never know. Maybe a nail through the feeder, maybe a chafed wire, who knows? Would a ground fault sensor at the head of the feeder have disconnected this fault? Yes, as soon as dad touched the dock trying to get out of the water. Would a ground fault sensor at the pedestal have tripped off power? No, the fault was in the feeder, not one of the boats connected to the feeder. The dock itself was energized: "hot." This facility is not "compliant" with the NEC, Article 555.
The lessons here are obvious. Thankfully, no one was actually hurt. But think of all the posts we've had over the past few years about ground fault sensors. This is why the NEC requires them. We were all walking on a "hot" dock. With grounded metal brackets holding the dock to the wall. We were all oblivious to the risk until that tennis ball went int the water and dad laid on the dock to retrieve it. Had the ball not gone into the water, just imagine what worse event could have exposed that risk?
I felt good that I could explain to the caretaker what was happening. I feel blessed that no one - not the dad and not the pup - was hurt. NEVER SWIM IN A MARINA OR AT A DOCK WITH POWER! NEVER!”
Jim
Monk 36 Hull #132
MMSI #367042570
AGLCA #3767
MTOA #3436