Adding a new circuit to a full sub-panel

[djkoell]

Hi everyone. I'm thinking of adding a mini split AC unit to my garage and would like to understand if its even possible with my current electric setup. I have a sub-panel in my garage (see attached photo) with no free spots for additional breakers. The main panel is on the other side of our two story house. I was hoping to add an additional 240V circuit for an 18k BTU mini split.

1) Is it possible to add another 240V circuit?

2) Would I have to replace a couple existing breakers with tandem breakers to free up the space?

Appreciate any guidance you all can offer on these two questions or other electrical gotchyas I should look into before beginning this project.

Thanks!

 

[rixtrix1]

Probably need more information, such as the size of the main service to your home, what size breaker is feeding the subpanel, wire size to subpanel, etc. It would appear that subpanel is already very well utilized. An explanation of the circuits on it would be helpful, too.

 

[brewchief]

You should be able to replace 4 full size breakers with 2 tandems to create room, looking at the panel label it appears that it will accept tandems in all spots, the label should say something like 16 space/32 circuit if so.

 

[Jim greengo]

I'd install a bigger sub panel with a main breaker in it,too many throws in current set up to kill it from what I can see anyway.

 

[Norcal]

I'd install a bigger sub panel with a main breaker in it,too many throws in current set up to kill it from what I can see anyway.

If it's in a attached structure a main is not required.

 

[wyliesdiesels]

I'd install a bigger sub panel with a main breaker in it,too many throws in current set up to kill it from what I can see anyway.

Maybe i missed it. Where did he say its a detached garage?

 

[matt_i]

Look for opportunities like a 240vac dryer outlet or a 240vac range plug which arent used because you are using nat gas appliances. Just abandon the wiring in-place and repurpose the breaker if it has the appropriate ampacity, or get a new one.

 

[CJ7VFR]

What kind of breaker is that on the right side of the panel, fifth one down from the top? It has two reset switches, both on the same single size breaker. Is that some type of 240V breaker?

Jim

 

[djkoell]

It's a tandem or duplex breaker used to put two circuits in the space for a single traditional breaker.

 

[TRWham]

That is an old style QO tandem breaker. 2 single pole breakers in one space but end to end not side by side.

 

[djkoell]

Here's a photo of my main 200A panel. It has a 90 Amp breaker for the sub panel in the garage. I'm not sure what kind of conductors they used to wire in the sub but I included photos of the house so you can see how far my main panel is from the sub in the garage. It would be pretty difficult to run new wires from the main to the sub. Note: My main panel is outside on the side of the house. This was a new thing for me when we moved here. Where I'm from panels are always in basements.

There was also a comment about reusing the circuit for our dryer. We actually did that already for a car charger in the garage.

Given I have a 90 amp breaker in the main, could I add a 20 amp 240V circuit for the AC unit if I upgraded the sub-panel or replaced existing breakers with tandems and made room for a double 240V breaker?

 

[CJ7VFR]

It's a tandem or duplex breaker used to put two circuits in the space for a single traditional breaker.

That is an old style QO tandem breaker. 2 single pole breakers in one space but end to end not side by side.

Interesting. I never saw one of those before. Thanks for the info!

Jim

 

[Jim greengo]

If it's in a attached structure a main is not required.

Makes it a lot easier to shut things down in an emergency.

 

[wyliesdiesels]

Makes it a lot easier to shut things down in an emergency.

Sure but you implied that it was required even though OP didnt say its a detached structure...

 

[EOC_Jason]

Given I have a 90 amp breaker in the main, could I add a 20 amp 240V circuit for the AC unit if I upgraded the sub-panel or replaced existing breakers with tandems and made room for a double 240V breaker?

Double check the label on your sub-panel to make sure there isn't any sort of restrictions, but seeing as how there are already some tandems that is a definite possibility to make space for a 20A double-pole for your mini-split. You should also remove the cover (best to throw the breaker going to that sub if you are not comfortable) to see the wiring situation... Like if there is even room for more wires or if it is already a rats nest. If there is room on the neutral & ground bars or if those are going to need to be re-done. It would also give you a chance to inspect the actual wire size coming into that panel to ensure it is correct.

One thing to consider is all those circuits, you need to figure out your existing load. I doubt you are pulling that much, but you definitely don't want to add the AC then all of the sudden the breaker going to the sub panels starts tripping because you are pulling too much current.

It looks like the top-right 2 breakers are labeled 220V, but they are two single pole breakers... Might want to look into that and replace with a proper double-pole if that is indeed what it is wired for.