Wiring Question

[daneb]

Hello everybody, I am new to this forum and have a question about the electrical setup for my teardrop trailer.

I have looked at example wiring diagrams none of which makes sense to me for some reason. Specifically I am trying to set up a system with two 12v deep cycle batteries for when I am away from home and shore power, and I would also like to have the option to hook up to shore power.

My question is, how do I have both simultaneously? I don't understand how the batteries could power a 120v AC outlet if they are running DC current. My other question is how the circuit would work. Would the shore power go directly to my outlets and lights, or would it charge my batteries to keep them full while the batteries provide the current.

My goal is to have two GFCI outlets for the galley, and a water pump for the galley. I will have a fan running for circulation, and three outdoor lights. I will also have 4 120v AC outlets non-GFCI in the cabin area along with two or three cabin lights.

I am not sure what types of shore power there are. I have heard of 30amp, but I am not sure how much voltage that provides. Also, what kind of connector will I need?

The diagram on http://tnttt.com/viewtopic.php?t=1941&p ... c&start=90 kind of made sense, but I still am not sure how to tell which gauge wire to use, or if I can hook up the AC source directly to the battery to charge it.

If anyone can provide me with an example schematic or drawing that has been used in the past it would be much appreciated. I am very confused and would like some clarification before I waste money or get shocked. Thanks for reading!

[MtnDon]

I don't understand how the batteries could power a 120v AC outlet if they are running DC current.

You are right batteries are DC. To get AC from a battery an inverter is used. The AC is 120 volt AC in Canada ? USA. In a TD or small trailer the DC is normally 12 volts.



If you are already thinking you need 2 batteries you will have better batteries if you selected two 6 volt golf cart batteries connected in series. That gives 12 volts and approx the same total battery amp-hour capacity as two 12 volt batteries in parallel. But that raises the question of why you chose two? What devices do you want to use? For how long? Start with that; the load in amps or watts is needed and how many hours or minutes a day when you have no place to plug in to shore power.

Campgrounds with power normally have 50 amp service for the big guys, 30 amp outlets for the mid ground and 20 amp outlets for smaller trailers and TD's. 20 amp is pretty standard for a TD.

I suggest making a list of all the electric devices you are thinking of possibly using. Make a list of the absolute must haves and a list of the other things you might like to have but could do without. Separate lists for DC items and AC items. If you plan on boondocking very much this is very important as batteries have limitations. After you know what you want/need then the wiring can be planned.



When plugged into shore power many of us with TD's and small trailers use a built in device that allows easy use of DC and AC. Google PD4045. It's a combination AC/DC "box". When connected to shore power it charges batteries and provides fused circuits to different DC and AC circuits. It is a converter, not an inverter.

Some of us also use generators when shore power is unavailable. 1000 or 2000 watts is all that is normally needed. Again, it depends on what electrical devices you need/want to operate.

Hope that helps you to get started.

[Kaz]

Being an electrician I would advise that all of your outlets be GFCI and make sure you ground your trailer frame to the grounding conductor of your AC supply circuit.

[MtnDon]

Is it not true that not all of the outlets need to be GFCI, as if wired correctly the first GFCI in a circuit will protect all the downstream outlets in that same circuit. In other words if you use a GFCI to feed power to other outlets everything is protected. Saves money. Just be sure to connect the incoming power to the LINE terminals and feed the downstream outlets from the LOAD terminals.

[Shadow Catcher]

The one thing I will contribute, plan on more outlets than you think you need

[Dale M.]

Is it not true that not all of the outlets need to be GFCI, as if wired correctly the first GFCI in a circuit will protect all the downstream outlets in that same circuit. In other words if you use a GFCI to feed power to other outlets everything is protected. Saves money. Just be sure to connect the incoming power to the LINE terminals and feed the downstream outlets from the LOAD terminals.

Yes...

Dale

[Kaz]

Is it not true that not all of the outlets need to be GFCI, as if wired correctly the first GFCI in a circuit will protect all the downstream outlets in that same circuit. In other words if you use a GFCI to feed power to other outlets everything is protected. Saves money. Just be sure to connect the incoming power to the LINE terminals and feed the downstream outlets from the LOAD terminals.

This is true, but if your gfci outlet goes bad none of your outlets work. If they are all gfci outlets you can have a bad one and still have working outlets else where. They can all be connected to the same source.I have had gfci outlets go bad in previous campers. I suspect vibration and road shock to be a contributing factor for failure.