Help with shore power plug

mikeporterinmd · Posted: Fri Dec 07, 2007 12:04 am Post subject:

You have to be careful with 30 amp inlet and shore cords. You need
full 10 gauge from the dock (shore cords are 10 gauge) through the
boat until you get to a properly installed dual pole 30 amp breaker
in the boat. Anything less is dangerous if you are plugged into a 30 amp
outlet.

The photos above showing 15 amp to 30 amp inlet do not show
a dangerous condition so long as the other end of the cord is
plugged into a 15 amp outlet with proper breakers for the
outlet.

We have people in our marina that use 15 amp cords going into
30 amp outlets. This will be the last year for that little trick. You
can cause a marina fire doing stuff like this. I read a good story about
such an investigation in an otherwise usually worthless magazine
a few months ago. In the story, the boater was not using twist locks
with screw down rings on the boat, and the connector was getting
hot from a bad connection. Eventually, it caught fire. Even though
the boat was totally destroyed, they were able to piece together what
happened and prove negligence on the part of the boater.

I'm fairly certain a similar situation caused a fatal boat fire I witnessed
a few years ago.

Mike

flapbreaker · Posted: Fri Dec 07, 2007 9:08 am Post subject:

Mike is correct that you have to be carefull with the above system. You can't treat it like you have a true shore power system. I definately wouldn't leave the boat unattended nor pull more than 15amps through the system. It is my understanding that the 15amp breaker will trip before overheating the cgfi cable that is wired into the 30amp outlet. I don't plan on testing this theory as I would only use the shore power cable to charge the batteries and maybe run a light or two. Maybe I'm mistaken but I'm under the impression that you would have to actually have a load greater than 15amps to cause a problem in the wiring. Feel free to correct me if I'm wrong.

marvin4239 · Posted: Fri Dec 07, 2007 9:35 am Post subject:

Sneaks · Posted: Fri Dec 07, 2007 9:48 am Post subject:

While surfing online, I found a 25 ft. marine shore power cable with a 30 amp connector on one end and a 15 amp connector on the other end that plugs directly into my Marinco charge connector. No adapters. Since the only "unattended" load is the battery charger and it's downstream from the GFCI and 15 amp breaker I'm comfortable using it at our marina.

No, as others have pointed out, it's not according to regulations. OTOH, how many of us have at least 4-5 computer devices and wall warts plugged into the same 15 amp receptical in our house via power strips etc.? AFAIC, that's far more dangerous than my setup on the Jenny B. It's a matter of risk and risk management. We all need to be aware of the dangers - whether we deliberately take a risk, however slight, is a personal decision as it should be.

With my present "constrained" boating "style" it's rare that I even connect to the marina's shore power but the convenience of plugging in both at home in the driveway, off a generator, or into my RV far outweighs the difficulty (and expense) of installing or upgrading to an "approved" shore power system in a 22 ft. boat.

Don

thataway · Posted: Fri Dec 07, 2007 5:31 pm Post subject:

The point about the plugs and inlets is excellent. The most common cause of boat fires is the entrance plug. Unfortunately many boaters do not turn off the circuits, they just unplug the cord. This allows arcing--carbon forms, there is more resistance, with more resistance more heat, the plug melts and a fire starts. The plugs (both cord and aboard boat) need to be inspected at least every 6 months. We replaced these on our larger boats about once every two years--this is with full time use, but we turned off breakers when we pluged or unplugged cords.

I dont' run even 15 amps with anything less than a #12 wire cord even with just 15 amps to the boat. Unfortunately there are lots of 50 and even 100 foot cords which are #14 wire--and this can be a problem.

For the cord we use from the genset, we have a true 20 amp plug (this is with the one plug at right angles to the other)--and use #12 wire, a length of only about 10 feet from the genset on the swim step to the 30 amp plug on the side of the boat. There is on reason for a longer cord with the gen set.

snal · Posted: Fri Dec 07, 2007 6:02 pm Post subject:

I ordered the "charger" plug today...actually ordered 2 of them. Amazon had them for like $17 each direct from Amazon. I might just put one on each side and get another GFI box.

mikeporterinmd · Posted: Mon Dec 17, 2007 11:06 pm Post subject:

flapbreaker · Posted: Mon Dec 17, 2007 11:42 pm Post subject:

marvin4239 · Posted: Mon Dec 17, 2007 11:57 pm Post subject:

You are correct the load on your extension cord carries will only be the sum of the items you have turned on in your boat. As long as your adapters are in good shape you should be okay. I wouldn't use the adapters for a permenant installation. On another note circuit breakers are mechanical devices that are prone to failure especially in a marine environment. I've seen extension cords melt all the way back to the receptacle without tripping a breaker. With a properly installed system the likelyhood of a short circuit is pretty remote. Make sure you use a good quality extension cord preferably #12 with good molded attachment caps (plugs) and no longer than needed.

mikeporterinmd · Posted: Tue Dec 18, 2007 3:52 pm Post subject:

marvin4239 · Posted: Tue Dec 18, 2007 4:56 pm Post subject:

One thing to think about is what you are attempting to do is being done in every home in america. Your table lamp probably has a 18 gauge cord good for 5 amps and it's plugged into a plug with either a 15 or most likely 20 amp breaker. Your vaccum cleaner may have a 16 gauge cord good for 10 amps plugged into a 20 amp breaker. Of course in a marine environment you want things right. I really think what you are describing is safe provided common sense and proper precautions are taken. As has been said before 99% of problems occur at the plugs and adapters. Make sure your plugs are in good condition and plugged in securely and take precautions to insure your cord doesn't get pinched as was mentioned.

Sea Wolf · Posted: Tue Dec 18, 2007 5:10 pm Post subject:

Two thoughts:

1. The West Marine West Advisor has a lot of information on Trouble Shooting Shore Power Connections that is a valuable resource that is found not only on the web connection linked, but also on page 433 of their current catalogue.

2. Have any of you with GFCI units found any reason to by-pass the units?

I set mine up so it could be by-passed in the series of incoming connections when plugging into my Honda 1000i generator. The standard advice is that the GFCI gets confused because the generator does not have a true ground, or has a "floating ground", if you prefer that terminology.

Joe. Teeth

Capn Jack · Posted: Tue Dec 18, 2007 8:56 pm Post subject: Shore Power Plugs

My greatest safety concern with shore power plugs is their location. I lost two of them to overheating due to corrosion when they were mounted below the gunnel. In this location they were constantly sprayed with salt water and difficult to keep dry inside. After the second failure I moved the outlet to the back of the cabin and haven't had another problem. Wink

mikeporterinmd · Posted: Tue Dec 18, 2007 9:38 pm Post subject:

captd · Posted: Wed Dec 19, 2007 8:25 am Post subject:

The job is probably all wrapped up by now. But Thataway is right. I had the Hunky Dory for seven years the 30 amp system was installed at the factory. The cord was so bulky and all adapters were so expensive. I, like Flapbreaker, always used the short reducer cord, and carried a small Number 12 extension cord. Even when using an electric heater. 30 amps were totally unnessesary with the 22 ft'er.

Mike does your laptop have a built in transformer on it's cord? What you are saying is dangerous is what happens in your house at every receptical. The smallest breaker in you house is probably 15 amp. 20 amp for appliances in the kitchen.
captd