When was the last time you looked at your shore power connections? Now, when was the last time you did a thorough look at ALL the shore power connections? If it has been awhile, it is worth taking a few minutes to look at your entire AC set up from the dock connection to your boat's distribution panel. The below inspection procedure could save you from a catastrophic event on you boat. I happened to be installing a wind generator last weekend and got to see the inlet side of the shore power connection and immediately shifted projects. What I found was melted wire and charred connections at the inlet, and, upon further inspection, a slightly burnt hot (white) wire going into the distribution panel. No indications otherwise that there was anything wrong with the shore power system...
*Take the time this weekend and walk through your shore power and potentially save yourself a larger project down the road. Let us know what you find and have a great boating weekend!
MAKE SURE YOU TURN OFF AND DISCONNECT SHORE POWER BEFORE PROCEEDING.
*Remember, de-energize the system and disconnect at the shore connection first.
*When reconnecting, make sure the shore power is the last connection before re-energizing the system.
1. First inspect your shore power cord connections. They should be clean and not showing signs of overheating or burn marks. Burn marks are more likely to come from arcing across the contacts due to movement rather than drawing too many amps. Attaching a cord to boat on the water that moves to whim of water, wind and every other external force causes potential for loose connectors to arc. Make sure you secure your connections, especially the one to your boat, with something that prevents movement at the connection and still allows enough catenary in the cord to account for daily tides and wind shifts.
2. If you do find damaged connections you have a couple of options: If the damage is minor, just clean the connections (light sand paper, stainless steel brush etc), wipe the area clean, apply dielectric to the connections and reconnect. Make sure you address what was causing the movement or the problem will just reappear. If the damage is more severe (deep burns, melted connectors - usually on the hot white wire) you will need to make a repair. Do not fret about having to buy a whole new cord yet, they make replacement end pieces that are fairly simple to wire in and will save you a decent amount of cash with just a little work (30 Amp female example). When you cut the shore power cord make sure the wire itself is in good condition, you might have to cut back a little way to find good copper (clean, supple wire). Make sure you get the waterproof cover replacement as well if the connection is in an exposed area.
3. Now lets look at the boat side. Inspect the inlet, if the plug showed sign of arcing then the inlet will likely also show damage. Same as discussed above. If the damage is minor, clean, add some dielectric and secure. If the damage is more severe you will need to replace the inlet (luckily just the interior, not the whole inlet). If you replace the inlet you will also get a good look at the boat side connection wires, which is our next step.
4. Regardless of whether or not you see damage on the inlet, you need to take a look at the backside of the system. Check the wires that connect the inlet to your distribution panel for loose connections and signs of overheating. Overheating can look like darkened covers or actually melted covers. Also, stranded marine wire should be supple, stiff wire is also an indication of overheating. Overheating could be a result of the arcing found at the inlet (if you found some), undersized wire or too much amperage draw. First check the size and type of wire you have connecting the inlet to your distribution panel. For 30 Amps systems you are required to have at least 10 AWG wire running but the Marinco connectors allow up to an 8 AWG and I highly recommend going up a size if you can. For 50 Amp systems 6 AWG is the requirement. Ensure you have a quality tinned marine wire as well (Ancor, Pacer, etc) . If you have enough installed wire to spare, make new connections at a spot far enough away from the damaged section to find clean copper. If you cannot, I recommend replacing the entire section (from inlet to distro panel) rather than placing a butt connector and adding additional resistance to the system.
Marinco has a pretty good reference document that might be worth taking a look at.
A Boater's Guide to AC Electrical Systems
Also, Marinco is not the only option for shore power out there. They are the main supplier for West Marine and OEM for many boats and a quality product but you can find other (perhaps cheaper) options if you look online. Often, you get what you pay for but there are many reputable manufacturers that make great products that do not make it to the major chain stores. Bottom line: be a smart and informed buyer.
DISCLAIMER: All information is provided for informational purposes only. Use at your own risk. If you have any questions or doubts, please contact a certified technician. If you find any errors in our methodology, please let us know!
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