Breaker for enclosed trailer?

[lachrimae]

Hi,

I think I've reached the end of my Googling skills and would really appreciate your guidance.

I am wiring my 6x12 enclosed trailer for a rooftop (13.5k) AC & four duplex outlets that will be used for basic purposes such as charging phones & computers and running some LED puck lights. Currently I don't have any plans for a DC environment.

I have a 30 Amp inlet that will be connected mostly to a pair of EU2000i generators and sometimes to a 50 or 30 Amp RV park outlet.

My issue relates to finding the best (safest) option for a breaker panel.
I am planning to use a 20A breaker for the AC and a single 15A breaker for the outlets.
If I use a main lug panel (no main breaker) those two breakers could total 35A and I am concerned that there would be a potential hazard since I'll be using a 30A extension cord as well as 10/2 wire from the inlet to the trailer's breaker.
I can't seem to find a 30A main breaker panel and most seem to be 100A or higher... So if I was to install a 100A main breaker I would still have the same issue of potentially sending 35A across my 30A extension cord.
Another alternative I've considered is using a 30A breaker on a main lug panel and then back-feeding it in order to create a quasi-main breaker, though this seems to be a controversial method on the internet, and if it's dangerous in any way I'm not interested.

Do you know if there is a 30A main breaker available on the market? Is it possibly ok to forgo a main breaker and just use the 20A & 15A breakers? Am I over-thinking this?

Thanks in advance,
Mark

[wa8yxm]

If you have only one power source (the 30 amp inlet) you do not use the backfeed lockout, because you are never backfeeding. you are only feeding.

I would suggest a 3 or 4 slot box.. or even one of the below box.

What is in my motor home

Though it is a 50 amp 240 volt box.. You can use half of it and skip the other half.

[lachrimae]

Thanks, I didn't realize that those exist so I'll have a look.

[time2roll]

Consider a 30/20 or 30/15 for the main to give an expansion circuit.
I would skip the lockout.

[lachrimae]

I wanted to drop in and say thanks again to everybody for your input. I think I finally figured out a good plan of action after reading what you had to say and stopping by an RV Center for further discussion.

I've decided against adding DC power since I don't have trailer brakes on this small trailer.

I'm planning to use a Square D 60A 2-space Main Lug where I'll put a 30A breaker on one side (back-fed to the 30A Inlet) and a duplex 20A breaker on the other side (the lugs will have a jumper between them so that the 30A can provide power to the 20A leg).

Here's a pic I found where somebody did something similar though it looks like they're supplying power direct to the left lug so there's no backfeed.

The one thing missing from the above photo is a backfeed breaker retaining kit, which is used to lock down the backfeed breaker to prevent arcing. I'm not sure if Square-D's retainer will work with this panel so I may have to improvise...

This panel comes with separate ground/neutral bars which is of course recommended on trailers. I noticed that some main lug panels have tied ground/neutral that can't be separated so you have to watch out for that...

[wa8yxm]

nevadanick wrote:
There will be a breaker on the pedestal or generator, why add another ?

In the park where I'm parked, Just 3 rows over from me, is a 50 amp site, It is not a 20/30/50 amp site, it is a 50 amp site, Just the one outlet, 50 amps, no other.

That is why you add the 2nd breaker,,, Unless that is you are paranoid and thus do not trust the park's breaker, If that is the case then you have TWO reasons.

[westend]

You could by a load center rated for, say 70 amps, and use a 30 amp main breaker. These smaller load centers are cheap and abundant. Last time I bought one, it was on sale for $26. I don't think you can beat that price with an RV product.

FWIW, I rewired my Starcraft with 50 amp service. The only downside is the cost of the cord and an adaptor for using when only 30 amp pedestal service is available.

I'd also suggest you have a 12v system on board. There is just too much variety of usage with 12v to pass it up. If you choose not to have any 12v wiring, you can mount a small SLA battery on the tongue to power the emergency break-away system.

[BurbMan]

First off, you need breakers. Granted the 30A on the pedestal will protect the cord, but that means running 10 ga to every light and outlet in the trailer. Using a panel with 20A breakers allows running #12 to the a/c and outlets.

I would also second the idea of a converter for 12v. If the trailer has electric brakes, DOT laws require it to have a battery on board and a breakaway switch to power the brakes if the trailer disconnects from the truck. So if you have a battery, you may as well have a charger onboard so you are charging the battery while you are plugged in.

The converter/charger allows you to run 12v lighting. The 12v is supplied by the converter while you are plugged in, the charger charges the battery with the added benefit is that you can have lights while unplugged using battery power.

Also if you want to add other 12v accessories like a stereo later.

Here's one model that has the converter, charger, and both 12v and 120v distribution panels all in one unit.

[D_E_Bishop]

Mark, first off, welcome to the forums. It seems from your post that you have an enclosed trailer not a factory RV, so you would be starting from scratch, Right?

If so any small sub-panel will do. I would start by looking on line for a local RV surplus or salvage business. I have a list somewhere but I just can't find it right now. They often have distribution panels for cheap that they pulled out of a salvage rig. There are several ways to run the shore power cord to your trailer and a good RV center should have a CAMCO and or Marinco catalogue you can pick out a way of attaching your shore line. When all else fails your local hardware store should be able to get you a small four opening 120VAC breaker panel. I think the hard part is going to be finding a surface mount panel that won't be thicker than the depth of your walls.

Not knowing what the inside of your trailer looks like or where you will mount your panel etc, it's hard to give specifics.

David

[lachrimae]

Thanks everybody.

If I'm understanding correctly it sounds like back-feeding is pretty common for RVs.

I was looking for detailed photos of the Progressive Dynamics panel that was mentioned and found this thread: http://www.classicwinnebagos.com/forum/index.php?topic=5326.0
Looks like it's also basically a back-fed main breaker.

I didn't have any luck when I went to a local trailer dealer but I'll go to some RV dealers today to see what they have.

Mark

[nevadanick]

There will be a breaker on the pedestal or generator, why add another ?

[wa8yxm]

You should be using a "Main" panel, one 30 amp breaker (The black wire on the shore cord goes to this) and the 20 and 15 go beside it.. Most RV dealers have boxes for you.. progressive Dynamics makes a real nice one that is designed to mount flush in a wall.. I would want at least one spare slot in case you ever decide to put in a 12 volt system.

NOTE: for simplicity,, You might want to consider a 12 volt lighting system.. The difference is instead of a converter and battery, you use a un-regulated power supply (Cheaper than a regulated one) you need about 2 amp per 1141 lamp.

I design and build my own power supplies.. Some of 'em are quite heavy, I do not do converters however (Have a design I can use if I wished to build one).

[tvman44]

The connector where you plug in will be protected so you could get by without a main breaker. But I would get a small 4 or 6 pole panel with out a main breaker and put a 30 amp single pole breaker wired backwards as a main, that is how the RV manufacturers do it most of the time.:)

[Dusty_R]

You don't need a Main Breaker in this case. The breaker, should be 30 amp, that feeds the receiptical that the #10 cord is pluged into, will protect the cord.

Dusty

[time2roll]

Just get a single pole 30a breaker and feed the panel through this breaker. You connect the cord to the breaker and it will limit you to 30 amps. This is how a standard RV panel is wired. NEC allows up to 5 branch circuits.

I do believe NEC allows 2x 20a breakers on a 30a supply without a main breaker.