[ianderson]

Hello everybody,

I had a rookie question and was hoping someone could help me with it. I was planning on buying a 220v 24,000 BTU mini-split for a garage conversion, and wanted to double check and see if my box could handle the extra load. Please see attached photo for image of box and breakers. I know the box has a max rating of 125 amps, but just wanted to make sure before I have an electrician come out and install the mini-split. Thanks for the help.

 

[mpoulton]

There is no way to tell for sure from the information provided. You would need to do a load calculation to determine the total existing load you have, and then see if you have enough extra capacity for the new AC. Without knowing what your existing loads are and what the new load is, nobody can tell.

 

[joed]

Your box has a double space to add the breaker. Whether the box will be able to handle the load is different issue.

 

[Fosti]

Panel loads

As someone else has already posted,you have the space to do it but do you have the capacity to do it is the question.You need to know your feeder size as well as the capacity of your panel stabs.Not so simple as "well I have the room so why not" because you could possibly cause your panel to be damaged as well as a possible fire. Hopefully you may just trip the main breaker if you add more circuits .

 

[gregzoll]

No way of telling, without you doing a load calc.

Most homes today now use less than they did in the 60's and 70's.

 

[joed]

because you could possibly cause your panel to be damaged as well as a possible fire

Not very likely unless there are other issues with the panel. The main breaker will protect from overloads.

 

[joecaption]

Have to agree with everyone else, not that matters.
Looks like you have one of my biggest pet peeves going on there.
Someone builds a garage and figures they only need a few lights and a couple of outlets so they cheap out and use under sized wiring, breaker, may not even have a subpanel or one that's to small.
Now there's no way to add high draw loads like A/C, welder, compressor, larger table saw without having to go back an redo all the wiring all the way back to the panel.
Good call to call in a pro to check it out.
Your going to like your mini split.
Draws very little power, quiet, simple to install.
I'd suggest building a platform for the outside unit to sit on not just setting it on a pad.
Helps keeping the leaves, blowing grass when mowing the lawn off of it, dogs peeing on it or messing with the wiring.

 

[AllanJ]

Your panel box has a 125 amp top (master) breaker.

You can put anything you want down below subject to the maximum number of breaker handles which may limit how many tandem breakers you may use. The number of handles should be listed on the label inside the panel.

Your city building code probably requires that you do a whole house load analysis before installing the new air conditioner. The results of the load analysis may or may not require that you upgrade the service which in turn will require that you put in a new panel. Depending on space, the existing panel may remain there with all of the branch circuits still inside and with a 125 amp feeder from a side breaker pair in the new panel.

Most cities require a permit for installing new circuits and/or installing central air conditioning.

An electrician should know about the load analysis and permit requirements and, if he wants you to actually pull the permit, he should be able to kibitz you on what to say.

By installing a subpanel now you can circumvent the number of handles restriction but not the load analysis and related consequences.

 

[dmxtothemax]

Do you know how to do an electrical load calculation ?

 

[ianderson]

Do you know how to do an electrical load calculation ?

I went online and found a generic excel spreadsheet. Do you know of any other resources I can use?

 

[ianderson]

Do you know how to do an electrical load calculation ?

Was planning on using the calculation spreadsheet from this site: http://www.electrical-knowhow.com/2012/01/residential-load-calculation.html

 

[ben's plumbing]

how about calling the electrican 1 st to see what you have to work with..then on his finding proceed from there.....Iam with joe...if you are adding a garage install new service for just the garage.. you won't be disapointed...:biggrin2:

 

[ianderson]

how about calling the electrican 1 st to see what you have to work with..then on his finding proceed from there.....Iam with joe...if you are adding a garage install new service for just the garage.. you won't be disapointed...:biggrin2:

That's probably what I'm going to end up doing. Better safe than sorry.

 

[IslandGuy]

Have to agree with everyone else, not that matters.
Looks like you have one of my biggest pet peeves going on there.
Someone builds a garage and figures they only need a few lights and a couple of outlets so they cheap out and use under sized wiring, breaker, may not even have a subpanel or one that's to small.
Now there's no way to add high draw loads like A/C, welder, compressor, larger table saw without having to go back an redo all the wiring all the way back to the panel.
Good call to call in a pro to check it out.
Your going to like your mini split.
Draws very little power, quiet, simple to install.
I'd suggest building a platform for the outside unit to sit on not just setting it on a pad.
Helps keeping the leaves, blowing grass when mowing the lawn off of it, dogs peeing on it or messing with the wiring.

Why is outfitting a garage with the standard light and outlet a "pet peeve?" NOT installing a 220v subpanel is your idea of "cheaping out?" I have to estimate only 1 out of maybe 250 garages ever need anything other than a light and convenience outlet. You may be all about the garage workshop, most people aren't.

 

[ben's plumbing]

Why is outfitting a garage with the standard light and outlet a "pet peeve?" NOT installing a 220v subpanel is your idea of "cheaping out?" I have to estimate only 1 out of maybe 250 garages ever need anything other than a light and convenience outlet. You may be all about the garage workshop, most people aren't.

its his opinion...and yes they vary:wink2:

 

[Jim Port]

Many times the utility will not set another service on the same property. If they do it is at a commercial rate.

 

[gregzoll]

how about calling the electrican 1 st to see what you have to work with..then on his finding proceed from there.....Iam with joe...if you are adding a garage install new service for just the garage.. you won't be disapointed...:biggrin2:

First thing they are going to do is charge you for doing a Load Calc.

 

[ben's plumbing]

First thing they are going to do is charge you for doing a Load Calc.

nothing is free:biggrin2: then op will know if he has enough power to do what he wants with garage...

 

[gregzoll]

nothing is free:biggrin2: then op will know if he has enough power to do what he wants with garage...

Tell me about it. But being a Lumper for helping to carry tools, etc. for the trades, along with food and drink, helps to grease the wheels.

I usually just grab a seat and watch. If I have a question about something I always ask, so I can tuck that piece of knowledge away for later.

 

[Jim Port]

First thing they are going to do is charge you for doing a Load Calc.

Is there a problem charging for a service ?