Questions about moving breaker box

[cheetah1]

I'm looking for some help regarding moving the breaker box in our 1968 Sovereign.

We've replaced the rear bath floor given the rotting from that rear hatch on the 68 Airstream of the old floor, and I'm at the point of building the framework for the vanity / sink area. It has dawned on me that this is the time to move the breaker box to a more accessible area. Currently - it is almost at floor level just to the right of the rear hatch access under the vanity area ( hopefully shows in the attached pic). I am thinking of moving it about 4-5' to the wall opposite it (to the left of the hot water tank) that separates the rear bath from the closet on the same side of the trailer that it is now.

I know enough to be dangerous! Household wiring I can get through - but this 120v / 12v system stumps me - especially given the aluminum wiring. I'm thinking this is as simple as putting a junction box where the current breaker box is - and then running the new copper wire from the junction box to the new location of the breaker box about 4 - 5 feet away. I am OK with using 4' of the black 30 amp cord to run it that additional 4 feet to the new location. BUT - THE QUESTION IS - since I have aluminum wiring in the trailer now, can I mix both aluminum wiring in that junction box ( from the wiring that is currently in place there) - with copper wiring to give me the 4' - 5' I need to move that breaker box? That would also mean that the breaker box in it's new position would have today's copper wiring in it even though the wiring in this 68 Airstream is aluminum.

I really do not want to replace the existing aluminum wiring in the trailer as all works and works well. Can anyone give me some guidance as to what I plan to do? ALSO - if anyone has a suggestion of replacing that breaker box with a newer model ( keep in mind the aluminum wiring) - I'm would love to hear it. I can foresee a time in the near future of potentially running a new circuit to the front of the trailer just for something like a microwave or TV and I don't think I have the space in the current breaker box to run that new circuit.

Thank you for any and all comments and suggestions!

[youngpeck]

I'm not an electrician but I know that you can mix copper and aluminum. You can also install a better breaker box which will handle more circuits. Even a smaller one (up to eight or more circuits) from a box store. There are conditions. You have to "float" the neutral so it doesn't tie into the ground, or earth system. Get this book:

https://www.amazon.com/Electrical-Sy...trical+systems

It will guide you through this and many other issues. A great resource.

[sgschwend]

The common approach to relocating an panel or sub panel is to install a junction box where the panel was, then add cables to each cable left behind and extend the new cables to the new panel location. In this way safe electrical connections are made and that is the objective.

Just remember both boxes need to be serviceable, they can not be hidden inside a wall.

[cheetah1]

Thank you for reply. Although that is what my thought process was, I just wanted to make sure I wasn't under-thinking this procedure. I am planning on joining each aluminum wire to its copper wire extension via a 2-port AlumiConn connector for each wire in the three white feeds shown (currently coming out of the wall to the left of the old box) and tucking all of those connectors within a new junction box at the original breaker box connection.

Could someone please enlighten me as to what the heavy red jumper wire actually does that is in the top of the original box and what gauge wire that needs to be?

[HowieE]

Looks like the original panel was a Split Panel and the red wire is the feed from the top side to the bottom side. You probably will not run across that when you buy the new panel. What you may find are panels with a main breaker and circuits with individual breaker. I which case you will install a 30 amp breaker in the main and 15 or 20 to the 3 original circuits.

The problem with aluminum wiring is the fact that the connection loosen over time and temperature. You have addressed that point with the connectors you plan to use. I suggest you get the connector compound and use it on any aluminum connection like wires from the breakers. Odds are you will never use the trailer long enough or with high enough current draw to cause the problem found in homes but be safe.

[markdoane]

The heavy red jumper connects the two legs in the breaker panel so that both sides of the split phase box have power.

You do not have a main 30a breaker in this setup to protect the main 30a supply cable. This is a dangerous setup, made more dangerous if you add in splices on the 30a main cable.

Please add a 30a main breaker.

[cheetah1]

Markdoane, thank you very much for this information. This is the way I got the trailer - but I'm not sure what previous owner did what with the wiring. We have had it plugged into a 15 amp garage circuit with a reducer plug, and have not run much more than the lights. I'm glad to have this information before going further.

Having said that, I believe I know what you mean by having a 30 amp main breaker in this load center to protect the 30 amp supply cable - BUT - I'm not sure how to put a 30 amp main breaker into this load box. I know there is one space available, but I'm not sure what it is I need to do or how to wire it to make the breaker a 30 amp main breaker.

Could you please give me some insight or direction with this?

Thank you!

[markdoane]

Cheetah1,

The normal and accepted way to install a main breaker is to purchase a single pole 30a breaker (same manufacturer as the box), and install it in the empty space in the breaker panel.

I would move the top breaker down one space and put the 30a breaker in the top spot, just to make it easier to find in the dark.

Loosen the lug with the black and red wires . Pull out the black wire and retighten the lug, with just the red wire under the lug.

Connect this black stranded wire to the bottom screw on the 30a breaker, then insert the breaker in the space. Carefully arrange the black wire so it's not rubbing against anything sharp.

The 30a breaker is your main breaker. Current flows in through the black main power cord, flows backward through the 30a breaker, and flows out through the power bus to the other breakers.

Since this is a split phase (240v) box, the bus bars are staggered so that adjacent breakers are fed from opposite bus bars. You don't have any 240v requirements, so you need a way to feed power from one bus bar, the one that is being back fed by the 30a breaker, to the other side. Thats the purpose of the red jumper wire.

Let me know if you other questions.

[HowieE]

Originally Posted by markdoane

Cheetah1,


I would move the top breaker down one space and put the 30a breaker in the top spot, just to make it easier to find in the dark.

Loosen the lug with the black and red wires . Pull out the black wire and retighten the lug, with just the red wire under the lug.

Connect this black stranded wire to the bottom screw on the 30a breaker, then insert the breaker in the space. Carefully arrange the black wire so it's not rubbing against anything sharp.

While I follow the schematic you describe here I am not sure that back-feeding a breaker to use it as a main would be in the spirit of good installation. To use 3 circuits and a main I would suggest buying a new 4 pole 110 volt panel with a 30 amp main.

[cheetah1]

Thank you! I could not figure out how to make one of the "regular" breakers the main breaker, and you've addressed that! I truly appreciate the advice!

[cheetah1]

Howie, thank you for your advice. With my plan of moving the location of this load center to the opposite wall, I was searching for a new load center with a pre-installed 30 amp main. My searches have been fruitless as most of what I am finding ( to keep the box as small as I can) is a 100 amp load center with no 30 amp main (or higher that I could switch out) preinstalled in a decent smaller size.

I've attached a picture of the load center I'm thinking of settling on. It is a Square D QO 100 A load center with 6 spaces and up to 12 circuits which was one of the smaller boxes I could find locally. The reason for the 6 spaces is that I do plan to run 1-2 more circuits to the front of the trailer in the future. However, the issue for me again was no main breaker installed nor is there a spot for it. So, that returns me to wiring the first breaker as the main.

Do you by chance know of a source for the 110 volt panel with a 30 amp main that you suggested in your message?

Thank you for your help!

[markdoane]

To save a little effort:

1. there are two types of breaker panels. They are called Main "Lug" panels and Main "Breaker" panels. You won't find a Main Breaker panel set up with a single pole 30a main breaker.
2. Main Lug panels do not have a main breaker. They are usually used as sub panels where the feed from the main panel is protected by a breaker in the main panel.
3. In the spirit of good installation, virtually every RV uses a main breaker that is back fed. There is nothing wrong with this type of install. The term "back fed" is actually a misnomer because this type of installation is not back fed. In an alternating current circuit, the electricity does not flow backwards through the circuit breaker. It flows in both directions equally at 60 cycles per second.
4. If you buy the Square D box shown in your post, be sure to buy an additional ground bar for the ground wires. The neutral wires and the ground wires must go on separate bars. The original ground bar in the box will be insulated from the box, use that one for the neutral wires. Install the extra ground bar directly to the box (there should be a place for this, with pre-drilled holes), and connect all the ground wires there.
5. If there is a bonded connection that bonds the ground bar to the box, it must be removed. There should be instructions in the box for doing that.

edit: you will still need to run a #10 jumper wire between the two separate buss bars.

[HowieE]

I yield to Mark's explanation in respect to RVs.

If the size of the panel is getting too big consider using the existing panel with the feed wired as original, black feeding the upper lug and red jumped to the lower lug. That retains the original 4 circuits available in the panel. Feed the umbilical cord through a separate fuse disconnect switch at the current location and wiring over to the panel at the new location.

[cheetah1]

Thank you both for sharing your knowledge! Markdoane, based on what you have shared in your last message, I'm going to buy this 100 amp box on Monday along with the separate ground bar. I believe it has the pre-drilled holes for the ground bar in the upper right hand corner inside the box. What you said about the neutral and ground wires makes all the sense in the world, and I was already expecting to add a ground bar to any box I bought that did not have one.

Could you please explain what you mean by the last line (edit) in your last message - "you will still need to run a #10 jumper wire between the two separate buss bars")? Why is that necessary and how do I do that on the box I am going to purchase?

Again, thank you for all of your help as your knowledge has been invaluable to my learning curve in dealing with the electrical in this vintage Airstream. With any luck, I should have the box moved and the electric throughout the trailer operating by end of week. That will be a blessing especially since I will then be able to use the air conditioning as I work in the Airstream in the 90+ degree heat we have been experiencing!

[markdoane]

Cheetah1,

The box you are going to buy is able to be wired for 240v operation. In a 240v application, you would have a black wire, red wire, white wire (neutral), and ground.

The black wire and red wires are both called the hot legs (black leg and red leg), and the voltage between them is 240v. The voltage from either the black leg or red leg to the neutral is 120v.

When you install a two pole breaker in the breaker panel, it will clip onto both the black leg and the red leg. A two pole breaker is for 240v high power appliance, like a stove. In order for this to work, the black leg buss bar and the red leg buss bar need to be next to each other so that a double pole breaker can plug into both busses. That's why the buss bars are arranged like they are.

But in your trailer, you only have one "leg" which is the black wire in your power cord that plugs into the pedestal at the campground. You don't have a red leg. So there is nothing to attach to the red lug in your panel. That means that only half of the breaker slots would have power, the ones that are connected to the buss bar that holds the 30a main breaker.

So buy a 30a single pole breaker, attach the black wire from the power cord to the screw terminal on the breaker, and plug it into whatever slot you like. Power will flow in through the power cord, through the 30a breaker, and into whichever buss bar that breaker is plugged in to.

You'll also need to buy all new breakers for the new box. The old ones won't work as they use a different clamping method to the buss bar.

In order to get power from the buss that holds the main breaker over to the other buss bar, you need to add a jumper wire (#10 wire) from the black leg to the red leg. Otherwise you will only have power to half of the breakers in your new panel.

The two lugs that need to be connected are the ones that are at the ends of the buss bars. In your picture, one of the lugs is mostly hidden behind the neutral bar. The other is to the right and below the main lug for the neutral bar. You might be able to use the red wire from your original box, but it may be too short.

Sorry it took me so long to get back to you. Good luck, post again if you have questions. It sounds like you are well on your way.

[cheetah1]

Markdoane, i cannot thank you enough for taking the time for the explanations and the help. It is truly appreciated. I hope to have time to complete this project at the end of this week. Thank you again!

[cheetah1]

Markdoane,

Thank you for your explanation and your patience. I have purchased everything I believe I need including the a grounding bar which I installed in the bottom right with the two screw openings provided there. BUT - I do have one more question. In looking at the old electrical box, there was a bare copper wire that at one time looks to have extended from somewhere inside the breaker panel and then was screwed to the frame itself. I always thought it to be the ground wire. Months ago when I first opened that box, this copper wire literally "fell out" of whatever it was connected to inside the box. It has not been attached to anything since - and all outlets and lights within the trailer work.

SO, do I need to attach some type of ground wire going from this new electrical box I am putting in the would go from the interior of the box directly to the inside metal of the trailer for some type of ground? I believe that when I am plugged into the house (which it has been since we have brought it home) - everything is grounded because the outlet on the home is grounded through the main load box of the home. BUT - we also plan on using a generator when we boondocks. So, do I need to install that ground wire and, and if so, where inside the box do I attach it? I am making the assumption that the other end of this ground wire can be attached via a grounding screw directly to the interior aluminum skin.

Given the weather here by St. Paul, I have opted to start this project on Monday once this humidity and high heat have passed. I have attached a couple of pics showing the location of the old electrical box on the lower right and the location of the new electrical box on the left. The new box nicely fits into the space between the two wing walls that separate the rear closet from the rear bath.

Thank you again for your help.

[markdoane]

Correct on the ground wire. I would try to move the new box up a couple of inches, you're supposed to be totally clear in front of the box for 30 inches. I'm not sure how well that is enforced.