overkill?

[Riptide]

While it is raining and/or cold I am trying to plan out the electrical for my trailer.

Is putting an outdoor type 110V breaker panel under my rear counter overkill as the next item down stream from it is going to be a GFCI outlet. I am also planning to put in a separate run to the front to support a 5000BTU AC unit I have sitting around in my garage. I have been told the AC unit should not be run off a GFCI circuit.

Should I spend the space on the breaker or leave it off?

Thanks,
Kerry

[eamarquardt]

I'm not sure what you're planning but highly inductive loads (like refrigeration compressors) sometimes trip GFIs even then there isn't a problem.

So, if your concern is having a GFI in your air conditioning circuit try it. If the air conditioner doesn't work remove the GFI.

The purpose of a fuse or a circuit breaker is to protect the wiring down stream of it. If you plug into a 20 amp source and your wiring is only rated for 15 amps and there is an overload your wiring could overheat and start a fire without the circuit breaker that is part of the source tripping. If your wiring is rated the same as or higher than your source you'll be fine (but it's always gonna be a guess unless your wiring is overkill). I'm not sure that you need a full blown panel but a circuit breaker to protect your wiring isn't a bad idea.

Hope this helps.

Cheers,

Gus

[Irmo Atomics]

Sounds like what I did. I have a 20 amp main breaker with 2) 15 amp circuits, each feeding a gfci outlet. I have a galley power strip and the fridge on one circuit and the cabin interior/AC or heat on the other. It's pretty basic, but it works.

[Bogo]

Have a breaker, but...

A few questions.
1) How many amp hookup? 15? 20? 30???
2) other circuits than listed? I saw GFI outlet circuit and air conditioner circuit.

It is possible to make your own main breaker panel with 1 to 4 branch circuits, and fit it into a standard 4" x 4" x 4" plastic electrical box. For 4 and 5 branch circuits it may get hard to fit all the wires inside the box, but with careful placement it should be possible.

I'd use marine circuit breakers like these:
http://www.amazon.com/Blue-Sea-7220-Magnetic-Circuit/dp/B000MMDM06/ref=sr_1_cc_3?s=aps&ie=UTF8&qid=1356061871&sr=1-3-catcorr&keywords=Magnetic+Circuit+breakers+30+Amps
One for the incoming power. One for each branch circuit if there are more than one circuit. Obviously with one circuit you only need the incoming main breaker. Size the circuit breaker for the wiring or devices it will be protecting.

http://bluesea.com/productdocs/7220 < dimension drawings and cutout templates for the above circuit breaker. The Blue Sea circuit breaker is a standard one that is made by a number of manufacturers. I'd bet $$$ that the Blue Sea ones are one of the others relabelled.

For your simple setup, you could have a 20Amp inlet tied to a single breaker. From that single breaker run the wires to both the GFI outlet, and the outlet you will plug the air conditioner into. Note: Make sure both the GFI outlet, and the air conditioner outlets are 20 Amp rated, and not 15 Amp rated. Doing this you could fit both the breaker and GFI outlet into a single 4x4 inch box that is deep enough.

There are less expensive breakers out there, but I recommend using magnetic or magnetic hydraulic because they have a stable current breaking amperage over a very wide temperature range. You can look through the circuit breakers that Mouser and Digikey sell to find cheaper and smaller ones, but you may pay the price for easy availability of spares going that way. Make sure you pay attention the the method of connecting the wires to them. For the higher amp breakers you will want screw terminals, and you could use 1/4" quick connects for the smaller ones. I know Digikey sells small switch type thermal breakers which are much like the ones used in some power strips. They could be used to cheaply protect and control single loads.

In the box I did for my 4runner I stuffed in a couple extra unassigned breakers for future expansion. I also used smaller breakers and put it into an even smaller project box. There is also a break before make DPDT switch in it to switch between the inverter and the AC inlet. That switch switches both the line and neutral wires.

[Riptide]

Thanks for the replies with all the suggestions and pictures.

Bogo, I really like the idea of saving the space by using a 4x4x4 box to hold a breaker or two, and drawings you linked make sense for mounting them to the front plate. This would buy me back some space I would really like to have. Additionally it would let me bring the pair of golf cart batteries I plan to mount later back to the center line of the trailer where I want them. Truthfully I was a little leery of the generic contractor grade breakers you see at the local big box store so those links you included are helpful.

Thanks,
Kerry

[Bogo]

The method has been used on boats for ages. I just stuck it into a 4x4x4 inch junction box because when you only need a few circuits, there is no need for a big panel. A cover door on a circuit panel isn't required, but a convenience for hiding and possibly securing the breakers. In fact it reduces the available switching actions allowed for killing power in an emergency. Unlocking the panel is one, unlatching it is two, opening is three, throwing a breaker is the fourth action. I think 4 actions is the limit under NEC.

Anyways, I recommend crimping the wires together or using a terminal strip. Blue Sea's terminal strip http://bluesea.com/category/82/36/products/2506 in 2 and 4 circuit versions is short enough that it will fit on the bottom of most 4x4x4 boxes. Crimp appropriately sized ring terminals onto the ends of the wires for connecting them to the breakers and terminal strip circuits. Wire all the green grounds together. Wire all the white neutral wires together. Each can be grouped together on their own circuit on the terminal strip. Keep ground and neutral separate, it is the job of the source like the RV power box, or generator to tie them together. The black wire from the power inlet goes only to the input of the main circuit breaker. From the output of the main circuit breaker I'd use a pair of wires to go to the inputs of the branch circuit breakers. The outputs of the branch circuit breakers would be wired to the black wires of the branch circuits. Connectors to connect the junction box to conduits, or clamp wires entering the box can be found at most home stores. Same for the terminal crimping tool and ring terminals. Remember to size the ring terminals for both wire size and screw/post size.

[H.A.]

Kj

[Bogo]

I'm familiar with them, and often use them myself, but I wanted something that most people can find at the store and would handle the current load of 20 Amps. Another issue is you need a large port size to allow a number of 12 AWG wire ends to be inserted for tying them all together. If it was my box. Where I tied the ground and neutral wire groups together I'd use a band crimp to crimp all the wires together, and then shrink some heat shrink tubing over it to isolate it electrically. The wire ends that connect up to the breakers would get ring terminals crimped on with heat shrink tubing to cover the base of the ring terminals. The reason I suggested using crimped on ring terminals is to help prevent the wire being wrapped around the screw. That never works on a vibrating platform.

I'd never use solid or coarse stranded wire in a vehicle, only medium to fine stranded wires.

[Irmo Atomics]

Since the subject of the original post was "overkill"
Has anybody had a problem using romex style wiring and standard household circuit breakers for their 120 volt power?

[H.A.]

Since the subject of the original post was "overkill"
Has anybody had a problem using romex style wiring and standard household circuit breakers for their 120 volt power?

This is the usual method with RV and traveltrailer manufacturers, At least in my experience with lots of 20 to 40~ish year old equipment.
I dont know whats coming out of RV factories today, But I dont expect its any better than the slap & dashed assembly crap of earlier times.

If decently secured and terminated NM cable, common boxes, breakers etc. will work fine in an RV.
There is a huge difference in transmitted mechanical energy of an RV bouncing along the road and a machine what vibrates.

[Shadow Catcher]

The Progressive Dynamics Inteli-Power® 4000 Series will accommodate a 30 main and up to seven branch on the AC side and up to 7 branch, the DC will handle up to 12 circuits and I am using them all. There are two GFI one for the AC unit and one in back for the refrigerator along with a 20A DC for the refrigerator (off grid). From personal experience it is amazing how quickly your "needs" seem to swell once you have the opportunity.

[DTCOOPER]

There is no danger in using your N3R load center for distribution. It is overkill in the sense of being N3R. Especially since it's not exposed to the elements.
BOGO is a bit confused I believe with his 4 action scenario. Its called the 6 disconnect rule. Which states that with the action of 6 disconnects or less, all power to a structure must be disconnected. As far as codes go; I'd venture a guess that a 4x4 box comes nowhere near meeting the volume requirements for installing multiple breakers and having adequate wire bending room. However, since Your trailer won't be inspected. So feel free to use any setup the you feel is up to the task. Use your load center, back feed a single pole 30 as the main, and enjoy the luxury of adequate space for all of your circuits and terminations. FYI- solid wire is the manufacturer's choice for RV wiring of AC circuits. And I wouldn't suggest using a GFCI on any motor load.
JMO of course. And it's worth what you're paying for it.