What size breaker(s)?

[madjack]

Read his post again. It's a 70 amp panel not a 70 amp breaker. He can use a 200 amp panel if he want's to. His original question was "what size breaker should I use?" Let me see here. He is going to plug his 20 amp rated extension cord into a 20 amp power panel and he is wiring his single circuit two receptacle system. The answer to his question is 20 amp breaker. Why is he using a 70 amp panel? Because he could not find a 30 amp panel. The size of the panel only indicates the maximum for the panel. It has nothing to do with the breakers or the wiring.

my point and my only point...thank you very much................................

[mikeschn]

...thank you George......................................................

[satch]

Who's George?

[Miriam C.]

I guess I didn't explain myself very well.
It protects the person by tripping before the insulation on the wire melts causing a dangerous situation to develop.

If you read back on this thread you have a guy wanting to run 12-2 to a 70 amp panel to feed the trailer.
People being what people are, [b]it's only a matter of time before that 70 amp service is full of breakers pulling twice the amperage that the feed will handle.[/b]
This seemed to be ok with madjack.
So be it, it ain't my ass on the line.

I am going to step out on a limb here a hope I don't do one of my backwards things.

Even if you loaded up the panel with breakers, and loaded on all the appliances, the service at the pole is only 30 amps to 40 amps and you are not going to draw 70amps from it. Now I can put on two hotplates, a coffee pot and hair dryer and might if I look at it wrong get something hot. But it probably won't be the cord

I was worried about the 12/2 cord and Mikes says I don't need to cause he doesn't know where you will get a 12/2 cord. 12/3

[satch]

I used a 60 amp box that has 4 slots, I put in 4 15 amp breakers ( I really don't need all that) but it gives me a shut off point to cetrain curcuits that I don't need on all the time. My shore power is usually 30 amp. Ran 12g wire, GFCI protected, proper ground, and all is good. Never had a problem with tripped breakers, or heated wires.

[Miriam C.]

We haven't had a good one for many months and will not have one now. I have split the response and will lock it if anymore flames are thrown.

Play nice please.

[BPFox]

[
I was worried about the 12/2 cord and Mikes says I don't need to cause he doesn't know where you will get a 12/2 cord. 12/3

It's a funny thing about wires. If you buy a 12 ga extension cord it will say 12/3 on the label. If you buy 12 ga romex it will say 12/2 even though it comes with a ground.

That said, the 12 ga extension cord is the right one if plugged into the 20 amp receptacle at the power source. Now if you were to use a 20 amp to 30 amp adaptor and you wired your trailer with multiple circuits and you pulled the full 30 amps using that 12 ga cord it would, in time, get warm. I doubt it would get hot enough to melt the plastic insulation, but it would get warm. It would have to be at full draw for some time for this to happen. This is all pretty academic because we are using worst case scenarios here. Based on the info provided, 20 amps might even be overkill.

It is pretty amazing where we have gone from a simple question being asked.


One more thing if I may. The original poster indicated that his 70 amp panel was only a two breaker panel. It's going to be real hard to "load up" this panel with breakers when it only has slots for two. Peace.

[Elumia]

Now that we've got that settled....

Here is some good information on selecting circuit breakers.
http://www.carlingtech.com/pdf/hydrauli ... eakers.pdf

And here is another interesting article from Siemens titled:
WHEN IS A CIRCUIT BREAKER NOT A CIRCUIT BREAKER?

https://www.sea.siemens.com/reselec/pro ... otacb.html


Bottom line - not all circuit breakers (or fuses for that matter) are the same. Choose them wisely.

Mark

[PaulC]

Who's George?

George was a little under the bridge type troll who used to spring out and devour people. He mainly paTROLLED this particular part of the forum. He no longer exists. Goodness and Faith took care of him in the end.
Cheers
Paul

[jmullan99]

Actually 30 amps is not overkill for any size trailer if you plan to equip it with extra electric goodies. For example, I plan to install an electric heater as well as an air conditioner. I will be using a two breaker 30 amp box for this. I like the looks of the panel style breakers shown here, but I am kind of cheap and I already have the panel box.

I am using a small 4 breaker, 60A box. One 30A breaker, (green) fed in reverse, as the main input breaker. 3 15A breakers. 2 feed a split receptical for fridge and micro. One feeds two other convenience outlets. NOTE: the other two breakers have not yet been installed in this progress photo.



Should the convenience outlets be near max, I would unplug the micro to do another high amp appliance. Works good for me.

[BPFox]

This is a good example of what we are talking about. This is a 60 amp box that is being used for a 30 amp service. I'm not sure what you mean by "feeding in reverse" your 30 amp breaker. I will assume you are using the 30 amp breaker as a "main" to power up the panel. While there is nothing wrong with this, it is redundant since your RV power source should already have a main breaker. This method does eliminate the need to jumper your breakers so to each his own as they say.

That said, it looks like you are also running 12 dc wiring. I am looking at red wires (12 v +) feeding a fuse block and black wires (12 v -) tied off together above the breaker panel with a wire nut. Is this correct? If it is I do have some concerns. First, it looks like the supply side wire is the same size as the individual circuit wires. While individual circuit wire only needs to be the size required for that individual circuit, the supply line needs to be large enough to handle all of the circuits together. Also it looks like you are bundling your 12 volt wiring and your 120 volt wiring together This is not a good idea since it could have a negative effect on your 12 volt components. Just some things to think about.

[jmullan99]

BPFox, you are correct in your analysis of what you see. The 30A is the main feed breaker. That protects me in case of input problems from a campground. Necessary? Not likely, and if I find I need more capacity, I may well re-do it a bit.

As for 120VAC being bundled with 12VDC, it only appears that way. Indeed where you see all the negatives bundled. It is just tucked there to keep out of my way during construction.

The system in the picture is a mid-point to running and testing. I am waiting to pick up a neutral/ground type buss bar to tie the negatives together properly. The main feed to fuse block is currently 14ga fused to 20A. It will be 12ga. The rest of the 12V branch circuits will remain 14ga fused to 5, 10 and 15 amps. THe 5A is for the 2 fluorescent fixtures within the box. 10A will feed a modified 14G extension cord to go to the tent for a small lamp and mini B&W TV. The 15A feeds the dual 12V outlets in the galley.

The simple orange cord was in place temporarily also. There is now a typical RV extension wired into the box. Oh, and I still needed to jumper the two halves as the main buss bar is divided.

I really should get some pics of the finished electrical. When I get back out there for more work and empty the extra stuff stored in the compartment, I will snap some.

Cheers.

[BPFox]

Ahhh....It's a work in progress. Good Idea setting up for testing before it gets all buttoned up. Good luck with the rest of the build.