Using 120Volt outlets in my cabin

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Gary C

First I want to state that I have NO electrical knowledge, so I appologize if this is pretty basic :) I have a question about my 120 volt electrical outlets in the cabin. I currently am at a marina that utilizes 20Amp power. However, my boat utilizes 30Amp power. I purchased an adapter which would allow me to go from 30amp to 20amp. I now ran into another problem with my shorepower...the adapter sticks down too much, so I can't plug my shorepower cable in. Why the explanation above? My outlets in the boat do not work (shorepower not plugged in). The batteries are charged. I just read somewhere that it requires an inverter to use the outlets when I do NOT have my shorepower plugged in. I'm unable to test the outlets with shorepower, because of the problem stated above. If I do not have an inverter, could this be the reason my outlets aren't working? Thanks, Gary
 
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Steve

DC/AC

Your batteries provide DC power, and the outlets are AC. An inverter will "change" the DC to AC, but a slight cost of power to do so (IE: It will take more DC power than it provides in AC.) The shore power is AC, and it won't hurt anything if it only provides 20 amps and the boat can take 30. That means that the shore power breaker will pop before your boat's will. You amy not be able to run larger loads with only the 20 amp service (like an electric cabin heater, a hair dryer, and a toaster at the same time. You should get the adapter situation taken care of soon however. Your battery charger does the opposent of the invertor (It changes the AC to DC to charge the batteries.) Without shore power, your only battery charge is when you run the engine. On that alone, and with only short runs of the engine, you could find the battery low and not be able to start your engine. I hope this helps, and good luck with the boat.
 
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Paul Mieszczenski

DC to AC

Gary, An inverter changes the DC current from your batteries to AC current for your outlets. They are used to run small TV's, coffee makers and similar low current items. They usually drain your battery banks pretty quickly. Since you did not indicate the size of your boat, I can't say if this is a good idea or not. The West marine master cataloug has a whole article on the subject of inverters. It's a good source of info. As for the adapter, how about a short extension cord that will fit into the 20A outlet and then plug the adapter into that. PM
 
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Paul Mieszczenski

Steve, We must have been typing at the same time.

Your post wasn't up when I started my reply. Good answer, PM
 
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Michael McCann

Dead outlets

Gary; Steve, and Paul are right on, but I would like to add 2 cents anyway. If you do not have an inverter, you would have to rewire the AC wiring to utilize one. You would still need to be plugged in to shore power to keep the batteries charged. As Steve, and Paul pointed out, an inverter uses more power than it provides. Michael
 
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Steve Dion

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Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Couple of options.

Gary: There are a couple of options for your power box problem. The first and probably cheapest is to either convert the end of your cord from a 30 amp to a 20 amp plug. The problem with this option is that if you go to another marina they will probably have a different power setup. Then you would need to convert again. The other option is the make a pigtail with a 30 amp on one end and a 20 amp on the other. Be sure that you get the correct 20 amp unit. There are two different types.
 
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Kevin Greene

simple

Go to the hardware store and get a Heavy Duty 3' extension cord. Plug that into your dock and your shore cord, with adapter, into the other end. 20amps of single phase power at your service.
 
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Gary C

Thanks!

Thank you all for your responses! I ended up cutting one end of my shorepower cable and put a 20amp end on it. So, I now have shorepower...and my outlets do work. I now understand what an inverter is, but am undecisive if I even need/want one. Again, thank you all for your help! Gary
 
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Steve Dion

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Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Just remember!

Gary: Just remember, if you go to another marina for a weekend, you may not be able to plug into shore power unless you get another cord or a 20-30 adapter.
 
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Josh

Inverter examples, and a few prices

Heres a place that I deal with on a regular basis, that usually has decent prices. The sites also give you examples of how many watts you need to power what. Most inverters give a wattage output...constant and peak. Problem is most equipment doesn't list a watt usage, with the exception of lights heh. Don't quote me on it, but I think you can get the wattage by multiplying volts (120) by the amps the device needs. A 1 amp device, 120 watts, a four amp, 480 watts. So if you get an inverter, make sure it has enough power to run what you want it to! And if you are running more then one thing at a time, make sure it can run them together. Josh Examples of inverters: http://www.sportsmansguide.com/showad.html?promo_code=WX1
 
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Josh

Woops, URLs

Opps..the url's didnt work. Go to www.sportsmansguide.com and do a search for inverter. Should give you a few examples of inverters and what they can run. Goodluck, Josh
 
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Tim Schaaf

power factor

There is also something called a power factor that sometimes screws up the calculations; you have to multiply the volts times the amps times the power factor to get the watts.
 
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Aldo Lozano

Power factor...

You right, Tim...But that apply mainly to loads like motor and similar inductive appliances.. For the resistives ones (toasters, stoves, heaters, etc...) the regular formula, Volts times Amps = Watts apply... Aldo alozano@monmouth.com
 
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