DANGER!! AC SHORE POWER LEAKAGE!!! Identifying and correcting AC shore power leakage.
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- Опубліковано 13 вер 2024
- *Caution* This is a DIY channel to help fellow boaters and share information. However if you dont have a basic understanding of electricity HIRE A PRO!! This is one area where mistakes can be deadly, not only for you but for innocent bystanders such as divers and family. However if you decide to tackle AC electrical on a boat be sure to buy and use the proper tools. The proper tools can make a mysterious topic much more understandable. Things like this AC Leakage detector, a good multimeter, and a handy AC probe detector are invaluable. Then you need to read read read on both the tool operation and the situation. Ill put links below.
More explanation on the video, including further discoveries. As part of the Lithium, Victron install portions of the boat are being rewired and brought up to modern standards. An ELCI was one of those items. So of course I wanted to precheck leakage prior to the ELCI install as not to lock myself out of shore power once installed. The video is not very good and was just what I managed to take while I was in "highly focused" fixing mode since I had serious concerns for the safety of possible divers or other unsafe conditions with 4 amps of leakage. 🤪 After ordering and receiving the Megger leakage clamp meter (specifically designed for this troubleshooting) checking the hot and neutral wires just on the backside of the shore power showed 4 amps of AC leakage. The limit for an ELCI is 30 mA. Several orders of magnitude difference..lol. I then put the clamp around the green ground wire of the shore power plug and it showed 3.7 or so amps. So that confirmed the vast majority of leakage was going out the ground wire. This is why diver never complained in the past. Next step was to go to the shore power pedestal and pull the plug and lay it on the dock. This disconnected the neutral and ground (they are connected somewhere upstream typically). I then went back to the boat and used a regular multimeter set to ohms and put the probes on the white nuetral and green ground put to measure continuity. It measured like .2 ohms. Pretty much tied together. It should have been reading open of Mega ohms, meaning little or no continuity. So at that point its clear the neutral and ground buss where tied together somewhere on the boat. I decided to begin removing the neutral bus wires one by one until there was no longer continuity. I decided to remove the only "add on" wire on the neutral buss that had a cheap crimp. Once that was removed the two busses read many mega ohms, so it was essentially open. I traced that wire to a bungle of three that clearly made up and AC circuit. Traced that to the back of the boat and found it ran into a typical AC receptacle. Opened it up and found the neutral and ground wires swapped. That receptacle was for a fairly new Xantrex battery charger. Reversed the wires and the AC leakage went away and now had under 4mA of AC leakage. Plenty of room for the 30mA ELCI. Also in this area were two AC boat cables that had wire nuts on them. Since I was in the area I was obligated to fix this issue as well. Opened the wire nuts up and of course the wires were good copper, but coated in green corrosion. Ticking time bomb. As I set out to fix these AC wires I discover that BOTH of these AC boat cables ran from the front electrical closet to the rear of the boat near the batteries, connected only to each other!!🤪 So of course I pulled them out all the way to the front and jumpered them to their appropriate busses with short wires of a few inches. Then it dawned on me. There was once an inverter charger located against the back bulkhead near the batteries. The two ac cables were the pass through. And at some time in the past the inverter charger died and the previous owner paid someone (i know who) to fix the issue. That person disconnected the AC cables at the inverter and wire nutted them together and left it dangling. In addition he added a basic Xantrex charger and wired it to the front AC panel, miswiring the outlet for that charger by crossing the neutral and ground. This person who did this work was supposedly a "Marine Electrical Engineer". Old boat wiring like this tells a sad story..lol.
I learn a lot from your videos. Keep em coming.
I have lots more coming regarding the Lithium and Victron systems. The system is up and running great as of now. The videos are a month behind or so.
Great video. Good example of just because it was like that, doesn't make it right.
This work was done by a "Marine Electrical Engineer" hired by the previous owner...lol
A GFCI circuit would have tripped in this case. If I'm not mistaken, most of the newer marina's have these on their power pedestals. Better to find this now than sitting somewhere away from home port. I'm guessing you have a galvanic isolator which kept your zincs and other drive parts from disintegrating? otherwise, I would expect damage. Good diagnostic work. Thank you.
If that particular plug was gfci It probably would trip. But there was no GFCI and this was a single circuit. No isolator. I have a ton of zincs and they did wear every few months. But because of the nature of the mistake the majority of the stray current was going up the ground wire back to pedestal....thank god.
I need to do that on my boat
If you have a regular clamp meter yo can do a basic check to see if there is a major problem like mine. Clamp the white and black wire on the backside of SP plug. Then clamp the green wire by itself.
@@mvintrigue-trawlerdiy1101 - thanks!