Panel out of space (need to add tandem breakers)

[sparco]

I am looking to install a dedicated breaker (20 amp) for a mini-split AC. My panel is full but I was thinking to install a tandem breaker and free up one slot but I wanted to make sure that me adding another breaker with be within the code.

1) My main breaker is 100 amp, however, the panel diagram says 200 amp panel - how do I read this? is my max 200 amp if I replace the breaker from 100 amp to 200 amp?
2) I have 26 breakers overall (4 of which are the double slot breakers for 220v)
3) here is the diagram with the tandem breakers allowance and overall I am below 40 breakers so I should be all set I believe but wanted to confirm. My line comes in from the top but the breaker is in the top left corner

 

[Megawatt]

I am looking to install a dedicated breaker (20 amp) for a mini-split AC. My panel is full but I was thinking to install a tandem breaker and free up one slot but I wanted to make sure that me adding another breaker with be within the code.

1) My main breaker is 100 amp, however, the panel diagram says 200 amp panel - how do I read this? is my max 200 amp if I replace the breaker from 100 amp to 200 amp?
2) I have 26 breakers overall (4 of which are the double slot breakers for 220v)
3) here is the diagram with the tandem breakers allowance and overall I am below 40 breakers so I should be all set I believe but wanted to confirm. My line comes in from the top but the breaker is in the top left cornerView attachment 99837

Firs off it reads 200 amp maximum and you can’t just install a 200 amp breaker because of the wire size. You didn’t show pictures of the inside of your panel so we could advise you further. As far as your panel goes is you can use it for any amperage but you cannot exceed the maximum rating of the panel

 

[sparco]

Firs off it reads 200 amp maximum and you can’t just install a 200 amp breaker because of the wire size. You didn’t show pictures of the inside of your panel so we could advise you further. As far as your panel goes is you can use it for any amperage but you cannot exceed the maximum rating of the panel

Thank you. Maximum is the cumulative 200 amp or 100 amp limit? I have 26 breakers (4 of which are double slot 230v) and my panel diagram says 40 breakers. Do U read this correctly?

 

[sparco]

Hi all, wanted to bump that up

 

[Megawatt]

Hi all, wanted to bump that up

It’s a 200 amp panel if it says 200 amp not 100

 

[Megawatt]

Thank you. Maximum is the cumulative 200 amp or 100 amp limit? I have 26 breakers (4 of which are double slot 230v) and my panel diagram says 40 breakers. Do U read this correctly?

If you are worried about overloading your panel you have no problem. You can’t add up all the breakers because it will always exceed 200, your breaker size is a calculated load not what you actually be pulling.

 

[Megawatt]

If you are worried about overloading your panel you have no problem. You can’t add up all the breakers because it will always exceed 200, your breaker size is a calculated load not what you actually be pulling.

If it’s says 40 circuit then it’s saying you can add the slim breakers instead of regular breakers. It should say like 20 space 40 circuit panel

 

[sparco]

Thank you, Megawatt!

If my panel is 200 amp but the feed and the main breaker is 100 amp, should my load calculation be based on the actual amperage fed into the panel (100 amp) or the panel's theoretical maximum (200 amp)?

 

[davesparks]

The way I read that label is that the panel can be directly connected via the top terminals and have a maximum supply of 200Amps to it, in this configuration it can have 40 outgoing ways connected.

Alternatively it can have a main breaker fitted in the top left position which will limit the maximum load to the rating of the main breaker, in this configuration it can have 36 outgoing ways connected.

So I would say from the information supplied your maximum load is 100Amps and can have 36 circuits connected.

I can't comment much further as I don't know US electrical code, everything above is based purely on the information and diagrams above.

 

[Megawatt]

Thank you, Megawatt!

If my panel is 200 amp but the feed and the main breaker is 100 amp, should my load calculation be based on the actual amperage fed into the panel (100 amp) or the panel's theoretical maximum (200 amp)?

Your load would be based on the actual wire size feeding the panel coming from the meter which according to you is 100 amps You still don’t have any worries because I have worked on a lot of 100 amp services and you still will not never see 100 amps on a single family dwelling. You just can’t exceed the amperage rating of your panel but you can go lower as per code. Always go by the size of your main breaker located in your panel.

 

[sparco]

I drew my actual panel and the breakers' amperage. How can I tell if I can take #7 & #8 AND #9 & #10 and turn them into 2 tandem breakers? and instead add another one that would be 240v - 20 amps.

How do I do the load calculation on with these numbers?

 

[Megawatt]

I drew my actual panel and the breakers' amperage. How can I tell if I can take #7 & #8 AND #9 & #10 and turn them into 2 tandem breakers? and instead add another one that would be 240v - 20 amps.

How do I do the load calculation on with these numbers?

First off you don’t have to worry about load calculations. Just go to Home Depot or Lowes and find you 4-15 amp breakers which is 1/2 inch slim line Breakers and turn off the power to your panel and remove the breakers that you have highlighted and install your new slim line breakers. Are you worried that you are going to overload your panel, because you added all your breakers and it exceeded 200 amps. You have to remember that all the breakers in your panel will not be drawing amperage that is showing. You have 2 different calculations in your panel, with the breaker size being your calculated load and then you have your actual connected loads which is not going to pull but 80% at the most of the actual breaker size if that much. Your design of your panel is fine.

 

[sparco]

First off you don’t have to worry about load calculations. Just go to Home Depot or Lowes and find you 4-15 amp breakers which is 1/2 inch slim line Breakers and turn off the power to your panel and remove the breakers that you have highlighted and install your new slim line breakers. Are you worried that you are going to overload your panel, because you added all your breakers and it exceeded 200 amps. You have to remember that all the breakers in your panel will not be drawing amperage that is showing. You have 2 different calculations in your panel, with the breaker size being your calculated load and then you have your actual connected loads which is not going to pull but 80% at the most of the actual breaker size if that much. Your design of your panel is fine.

Thanks you. I didn't necessarily worry about overload but just wanted to make sure I don't violate the code. What confused me is that I have a 200 amp panel but it's only on "paper" because the main breaker is only 100 amps and that I am putting in too many breakers and have a few big once like 50 & 30.

Just for my edification, what is the limitation by code? if I have more than 40 breakers? how is the load calculation impacting all of that? as I understand that not everything is going to be working all at once.

 

[Megawatt]

Thanks you. I didn't necessarily worry about overload but just wanted to make sure I don't violate the code. What confused me is that I have a 200 amp panel but it's only on "paper" because the main breaker is only 100 amps and that I am putting in too many breakers and have a few big once like 50 & 30.

Just for my edification, what is the limitation by code? if I have more than 40 breakers? how is the load calculation impacting all of that? as I understand that not everything is going to be working all at once.

You are exactly right everything is never on at the time. HVAC is always your largest load. As far as adding slim line breakers the code says your only allowed 42 circuits but that also includes the main breaker. As mentioned above I stated that the panels says 20 space 40 circuits and the slim line breakers you have 2 breakers using the same phase instead of 1 one inch breakers which was designed for future additions. Good luck my friend

 

[sparco]

You are exactly right everything is never on at the time. HVAC is always your largest load. As far as adding slim line breakers the code says your only allowed 42 circuits but that also includes the main breaker. As mentioned above I stated that the panels says 20 space 40 circuits and the slim line breakers you have 2 breakers using the same phase instead of 1 one inch breakers which was designed for future additions. Good luck my friend

Thanks again for all the advice!