1973 Argosy 22' Main Breaker Panel adding AC unit

[cjfoster]

Hey all,

My 73' argosy is 30-amp service, currently supplying 120AVC to only 3 outlets + refrigerator. Everything else, all lights, etc.. is on 12v. Currently there is only one 20amp breaker. I'm planning on installing a Dometic Penguin II A/C unit and need to install another breaker.

Can anyone advise on the kind of breaker I would need? Twin-breaker 15/20, etc.. I see the main power plug hot wire coming into the 20amp breaker. How would I add another breaker to the mix and what kind of breaker goes into these old GE panels? Thanks!
(pics attached)

[A W Warn]

Technically that one breaker is the main breaker, since there is only one circuit. If you add a second, then there is no main breaker.

I'll suggest to you to take this opportunity to upgrade your distribution center, instead of adding a breaker. It will not cost a lot and it will be safer, and give you the opportunity for future upgrades (maybe adding ground fault or arc fault, or some new equipment like a microwave or television)

This is what I would do:
Replace the panel with something like this>
https://www.homedepot.com/p/Square-D...0SCP/100190554

Get a new single pole 30 amp breaker to act as the main breaker. The black wire where power comes into the box will connect directly to that breaker, not to the lugs in the panel. Then you will have space for multiple feeder breakers.

Since most load centers are set up for residential use 240v, the 120v coming through the 30 amp breaker will not energize both lugs, so alternating spaces in the load center will not be energized unless a path is provided. A jumper wire is needed between the lugs. Use a 10 ga wire, same size as the incoming wire to provide a conductor between the lugs.

What I suggested above can be done for less than $50, for this distribution center and three new breakers. If you add more or different types of breaker the cost will be additional.

To answer your question:
Take you old breaker with you to make sure when you purchase. I think it is this one> https://www.homedepot.com/p/GE-Q-Lin...1120/100356508
If you use the existing panel, you will need to add that jumper wire between the lugs. This is what is not safe, because the panel will be hot without a main breaker for emergency disconnect. You would have to go outside and unplug to kill power.

ps:
That loose black copper wire obviously was connected at one time. Do you know what it feeds, and do you want it energized? That could be another reason to upgrade.

[A W Warn]

ps2: Taking a closer look I notice there are different gauges of wire inside the panel. 14 gauge wire should be on a 15 amp breaker. 12 gauge wire should be on a 20 amp breaker. 10 gauge wire should be on a 30 amp breaker.

[strangepod]

You COULD make this work and work safely - however as a previous post said, I think you are better off upgrading the panel. Square D is a good panel, also GE makes one that will work also. Make sure your breakers match the manufacture of the panel. For instance a GE breaker will not fit into a Square D panel and visa versa. Also Square D (and Eaton) have two style panels and take different type breakers. If you are adding an AC, it should be on a 20amp with 12/2 wire and your main would be a 30amp that is back-fed into the panel. As the other poster pointed out you will have to use every other lug on the panel to install your beakers UNLESS you add a 10ga (min) wire across the main buss bar (at the lug tie points) since these panels are set up for 240, this will allow you to use all of the slots in the panel.

John

[cjfoster]

Originally Posted by A W Warn

Technically that one breaker is the main breaker, since there is only one circuit. If you add a second, then there is no main breaker.

I'll suggest to you to take this opportunity to upgrade your distribution center, instead of adding a breaker. It will not cost a lot and it will be safer, and give you the opportunity for future upgrades (maybe adding ground fault or arc fault, or some new equipment like a microwave or television)

This is what I would do:
Replace the panel with something like this>
https://www.homedepot.com/p/Square-D...0SCP/100190554

Get a new single pole 30 amp breaker to act as the main breaker. The black wire where power comes into the box will connect directly to that breaker, not to the lugs in the panel. Then you will have space for multiple feeder breakers.

Since most load centers are set up for residential use 240v, the 120v coming through the 30 amp breaker will not energize both lugs, so alternating spaces in the load center will not be energized unless a path is provided. A jumper wire is needed between the lugs. Use a 10 ga wire, same size as the incoming wire to provide a conductor between the lugs.

What I suggested above can be done for less than $50, for this distribution center and three new breakers. If you add more or different types of breaker the cost will be additional.

To answer your question:
Take you old breaker with you to make sure when you purchase. I think it is this one> https://www.homedepot.com/p/GE-Q-Lin...1120/100356508
If you use the existing panel, you will need to add that jumper wire between the lugs. This is what is not safe, because the panel will be hot without a main breaker for emergency disconnect. You would have to go outside and unplug to kill power.

ps:
That loose black copper wire obviously was connected at one time. Do you know what it feeds, and do you want it energized? That could be another reason to upgrade.

Thanks a ton for your recommendation. I think this is a good opportunity to upgrade the panel. Regarding that lone black wire, It was going to no where on the other end of it, so I ripped it out.

Quick question/clarification:
Ill probably get that exact Square D panel (6 space to plan for future growth). So the main line will come directly into a new single pole 30-amp breaker. To reiterate, when that breaker is flipped on, every other alternate 'feeder breaker' will be energized? Honestly I will only have 3 to start, 1x 30-amp main and 2x 20 amps (1 existing and 1 new for A/C). So for now, I don't know if i'll run the jumper wire (until i need more spaces). Am I on the right track here?

I guess I'm used to see the main come into a Lug, not the breaker itself. Just wrapping my head around it.

[A W Warn]

Originally Posted by cjfoster

Thanks a ton for your recommendation. I think this is a good opportunity to upgrade the panel. Regarding that lone black wire, It was going to no where on the other end of it, so I ripped it out.

Quick question/clarification:
Ill probably get that exact Square D panel (6 space to plan for future growth). So the main line will come directly into a new single pole 30-amp breaker. To reiterate, when that breaker is flipped on, every other alternate 'feeder breaker' will be energized? Honestly I will only have 3 to start, 1x 30-amp main and 2x 20 amps (1 existing and 1 new for A/C). So for now, I don't know if i'll run the jumper wire (until i need more spaces). Am I on the right track here?

I guess I'm used to see the main come into a Lug, not the breaker itself. Just wrapping my head around it.

Yes, you are on the right track.

Both of my trailers came from the factory with a back fed 30 amp main and a jumper between the lugs. I've owned six different Airstream trailers, all wired this way.

I suggest you go ahead and install the jumper. You can get that 10 ga wire cut to length for about 20 cents. I would ask for red so it will be visible and noticeably different.

If you don't install the jumper you will have to skip spaces between breakers. It's difficult to get those knockout strips out in alternating spaces.

[cjfoster]

Originally Posted by A W Warn

Yes, you are on the right track.

Both of my trailers came from the factory with a back fed 30 amp main and a jumper between the lugs. I've owned six different Airstream trailers, all wired this way.

I suggest you go ahead and install the jumper. You can get that 10 ga wire cut to length for about 20 cents. I would ask for red so it will be visible and noticeably different.

If you don't install the jumper you will have to skip spaces between breakers. It's difficult to get those knockout strips out in alternating spaces.

Agreed, makes the most sense to add the jumper (+1 on the red wire). Pro tip on the difficulty on the knockout strips doing the alternate spaces route. Will update the thread with new pics when completed.

[Wazbro]

The panel in a trailer is a sub-panel. The outlet you plug into (often at another sub-panel on a pedestal) comes from the main panel. Feeding a sub-panel through a breaker is fairly common. Also in sub-panels it is against code to bond ground and neutral.
A big safety reason to not bond neutral and ground on a trailer, at least some older campgrounds only run hot and neutral wires to pedestals and use earth ground, if the earth ground is poor and they reverse the polarity you would be connecting the hot wire to the frame and shell of your trailer and the breaker would not trip.

[A W Warn]

cjfoster,
Wazbro is correct about bonding. Don't want that neutral bonded to ground.
If you get that Square D load center, the one I suggested, a green machine screw will come with it. That screw will be either installed in the neutral bar or loose. Don't use this bonding screw, discard it.

If the load center does not come with a ground bar, you can use the one that is inside the existing panel. Just make sure it is securely connected to the metal box with a proper grounding screw.

[bibbs]

I think this is a lot simpler than you think, electric code allows up to 6 breakers before you need a main. The cord feeding the trailer is fused at the pedestal 30amp, simply ad a jumper between the main lugs, and a new Circuit breaker on the other space.