Why isn’t my service (Main) panel space being utilized and everything is being fed to a sub panel?

Question

Edit: As requested please see the attached photos.

@manassehkatz-Moving 2 Codidact Thank you for the reply. As you and a few repliers mentioned, I figured out how to upload some photos so hopefully there is some more clarity. I appreciate the guidance. As you said, location does seem like the driving factor behind not using that space. If I need to add another circuit to one of the available spaces on the service panel, it seems like I'd have to run the wires from the intake of the subpanel, down and through to the exterior service panel. This seems like the quickest way to add a circuit, not sure that is code complaint though.

It is also possible that you can use "half size" breakers to add more circuits. Or merge small circuits, within certain constraints. Or it may be time to add another subpanel using 2 of the spaces in the main panel.

This is also a possibility and would require some research into the feasibility and complexity. Main reason is to add more receptacles in the garage for a fridge, air compressor, tool chargers, etc. Currently only have 2 receptacles which power a freezer and the garage door motor on the ceiling. I've already popped the breaker a few times plugging into same outlet as freezer. Too much of a hassle to plug into the ceiling every time. Ive read that its best to have a dedicated circuit for large appliances. So if I add a fridge and other smaller things to a circuit with a freezer and garage motor, I feel this might be too many.

Either way, please take a look at the photos (edited into the question) and let me know what you think! Thanks again.

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New homeowner here with two basic questions that I couldn’t find the answers too. Looking for some guidance.

First is the unused space in my main panel. From a few hours of YouTube I understand that my meter feeds to an external, Service (Main) panel box on the exterior of the home. On the bus bars there are two double 150amp breakers that would cut power to the home and the neutral bus is used to connect the neutral and ground wires (no separate ground bus bar, no jumper cable between ground and neutral bus but accomplishing the same thing by having it on one bus bar, I believe).

The question is regarding the unused space for breakers on this panel. In the main panel under the main breaker there 8 locations that can have breakers installed. Currently there is one 30amp breaker installed. The same thick diameter wires that come from the meter are also used on the bottom to daisy chain the main panel in series to a sub panel on the inside of the garage. In my sub panel all the bus bar locations are full and I cannot add more breakers. The confusion is why didn’t they use the available space in the main panel? And is there any issue with adding a 15/20amp breaker on any of these locations (similar to the 30amp)? I assume the 30amp was added after and looks like an outlet for charging an RV.

The second question is regarding the main panel at the top where the large diameter wires come from the meter into the panel and into the terminals. It looks like some thinner wire is being used as a jumper (wrong terminology most likely). There are individual wires coming from each of the bus bar terminals for both hots and the neutral that all terminate in one location. Looks like they were going to be used for traveling outside the panel as there is a plastic cap capped off that protrudes outside the exterior of the panel box. I have no idea what this is used for or the function. Just looking for some ideas on why this would even be used.

I know this is long winded but would appreciate some guidance. For context the house was built in 2001 and during the home inspection no red flags were raised. Just noticing things now as I am trying to add additional circuits.

Answer 1

A small (8 spaces is small) main panel outside near the meter is becoming more come due to recent code changes, but some older homes have it as well. The typical setup is that the main breaker in that panel protects the wires from the meter/provides protection for the entire service and it serves as a manual disconnect for the entire service should that be needed for maintenance (the alternative is "pull the meter") and also for safety if there is a fire or serious damage to the building. The ability for firefighters to quickly and easily shut off all power to the building is rarely needed but vital when it is needed.

The small panel typically provides a few functions:

• Full service capacity (i.e., same as main breaker) to a subpanel - that is your garage.
• Feeds to one or more subpanels. That's the 150A feed to your house "main" panel. The one key thing there is that while it is likely designed as a "main" panel, it should be installed as a subpanel - meaning neutrals on neutral bar, grounds on ground bar and no neutral/ground bond. That is an important thing that you should double-check, and is something the home inspector arguably should have checked.
• Other large loads - HVAC, EV charging, RV are all logical for various reasons. Technically anything could be installed here.

Note that each 240V circuit requires 2 spaces, so 8 spaces doesn't go very far. There are "half size" breakers for many panels, but there are also good reasons why those aren't used as much in these outdoor main panels, including that some breaker brands don't have "half size" breakers larger than 20A, and most of the loads in these panels are larger than 20A. But the specifics vary a lot and you may indeed be able to add a few circuits.

The biggest reason often why these panels are not used for general circuits is location. For a bunch of reasons, traditional "main" panels are often located indoors, even if they are actually subpanels.

In my sub panel all the bus bar locations are full and I cannot add more breakers.

This is where pictures matter a lot. You may have a smaller panel (e.g., 20 spaces) and be able to replace it with a larger panel (e.g., 30 or 40 spaces). Or it may be that you have a large panel and when originally installed it was half full but over time additional circuits were added and now it is full. It is also possible that you can use "half size" breakers to add more circuits. Or merge small circuits, within certain constraints. Or it may be time to add another subpanel using 2 of the spaces in the main panel.

And is there any issue with adding a 15/20amp breaker on any of these locations (similar to the 30amp)?

Absolutely fine to do that. Often that is done as a "convenience receptacle" but it can power a string of receptacles throughout the house.

It looks like some thinner wire is being used as a jumper (wrong terminology most likely). There are individual wires coming from each of the bus bar terminals for both hots and the neutral that all terminate in one location. Looks like they were going to be used for traveling outside the panel as there is a plastic cap capped off that protrudes outside the exterior of the panel box.

That sounds suspicious, but pictures should at least determine whether it is safe or not.

Answer 2

Your outdoor panel is something I call a "Ranch Panel" and everyone else calls a "Trailer Panel" lol. It's designed for a ranch, when the utility delivers power to a post and then you need to run the main line (off the bottom thru-lugs) to the house, and then feeders to barn, shop, well house, etc.

Since NEC 2020 now requires outside main disconnects (and many other cities have for decades) for firemen's use, using a ranch panel instead of a simple "meter + main only" is a smart play. It gives you 8 extra breaker spaces, and nobody ever said "Oh no, I need to add an additional circuit but I have plenty of breaker spaces, whatever will I do?" Spaces are cheap, get plenty. I hope that answers your confusion about empty breaker spaces: that's just your builder leaving you some expansion room. And sure enough, here you are wanting to add a circuit! This will happen again. Generally all 8 spaces get wiped out with solar, generator interlock, surge suppressor and EV station.

You can certainly add a breaker into any panel you choose. The loads on that breaker will calculate as part of the house's Load Calculation in any case, but 120V circuits are generally not counted except for permanently installed equipment.

A freezer takes a TINY amount of power - don't take my word on it, get a Kill-A-Watt and measure it. It may take 100 watts (under 1 amp) when running and maybe 2-3 amps when defrosting (if it even does that). So the freezer load is negligible; if a tool is tripping the breaker it's functionally doing that all by itself. Perhaps the breaker has GFCI or AFCI functionality and the tool has a ground fault or arc fault.

I think it's a win for refrigerators and freezers to have dedicated circuits to prevent breaker or xFCI trips due to other appliances sharing the circuit.

Now you mentioned something about a service-side tap using smaller wires. Some installers improperly stick a second wire under the lugs intended for the service supply wires. Such an installation needs to be corrected, as it will cause terminal burn-up. However, a "vampire tap" clamped inline along the service wire is allowed, and some panels are "solar-ready" or "surge suppressor-ready" with an extra set of small terminals on the service side of the main breaker. Both of these installation methods are fine.