twin breaker installation

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cornbread

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Trying to find the number of twin breakers I can install in a 120v lighting panel. Is there some code limitation? Any references would greatly appreciated.
 
If I am understanding you.
Their is no limit to the number of breakers. It's based on the load.
However most panels don't exceed 42 as of now.
 
It would the the manufacturer that would state a given panel can accept tandems, not the NEC.

I quick way to check is to look at the model number. If it has somethine like 2030 or 2040 or 3040 in the model number, that means it has 20 or 30 spaces, but allows 30 or 40 circuits.

You can also look for the manufacturers rejection feature on the bus bar or mounting rail. If all the spaces contain that rejection feature, no tandems are allowed.
 
cornbread said:
Trying to find the number of twin breakers I can install in a 120v lighting panel. Is there some code limitation? Any references would greatly appreciated.
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As stated the number of tandems in a panel would be related to the type of panel bought. For instance, you can have a panel that will accept 20 full size breaker or 40 twins (same as 20 piggybacks or tandem breakers). Either scenario will give a max of 40 circuits.

Other panels could be a straight 40 circuits and no twins are allowed, while other panels may have different configurations.

Remember not all panels are designed the same.
 
There is usally a sticker on the panel or cover that shows you where in the panel twins are required and if you put them in the wrong places it wont pass inspection.
 
I have seen a few panels that did not give you a busbar drawing identifying where twins can be used but they will list approved breakers. Remember just because a mini fits does not mean it is allowed.
 
Buck Parrish said:
If I am understanding you.
Their is no limit to the number of breakers. It's based on the load.
However most panels don't exceed 42 as of now.
Click to expand...

I don't see how the load matters. :confused:

The limit is based on the panel manufacturers discretion.

There are Sq D 40 ckt panels that allow 20 tandems for a total of 60 circuits on the market now.
 
As others have mentioned it depends on how the manufacturer sets up the panel and passes it thru UL. Some mfr's are now making new panels that are capable of 60+ circuits. The best way you can tell is on the panel cover. Let's say you are using a 30/40 circuit breaker panel. The directory on the door will look like this : the door will show the first 30 spaces (10 on each side) as follows :

___________ ___________
___________ ___________
___________ ___________
etc.

The next 10 spaces (5 on each side) as follows :

__________ ___________
----------- ------------
__________ ___________
----------- ------------
__________ ___________
----------- ------------

If your breaker panel does not show the layout of the panel then you cannot legitimally use tandem breakers. If it's an older panel, while the breakers may fit, it could, in all probability, be a code violation.
 
cornbread said:
You stated it could be a code violation...what section of the code would be refering to?
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Off hand I would say Article 110. If you look at 110.3(A)(1)FPN : Suitability of equipment use may be identified by a description marked on or provided with a product to identify the suitability of the product for a specific purpose, environment, or application. Suitability of equipment may be evidenced by listing or labeling.

I have failed an inspection on an installation like this once before. I had to add a 20 amp SABC to a remodeled kitchen. The HO had an older Sq-D-QO breaker panel with numerous tandem breakers already installed. So I added one of my own. When the inspector came out and looked at the panel all he said was "Get a manufacturer's document stating that it is acceptable to to install all these tandems in this panel". Long story-short I had to change out the HO's panel at his expense. More work and more $$ for me.;)
 
goldstar said:
Off hand I would say Article 110. If you look at 110.3(A)(1)FPN : Suitability of equipment use may be identified by a description marked on or provided with a product to identify the suitability of the product for a specific purpose, environment, or application. Suitability of equipment may be evidenced by listing or labeling.

I have failed an inspection on an installation like this once before. I had to add a 20 amp SABC to a remodeled kitchen. The HO had an older Sq-D-QO breaker panel with numerous tandem breakers already installed. So I added one of my own. When the inspector came out and looked at the panel all he said was "Get a manufacturer's document stating that it is acceptable to to install all these tandems in this panel". Long story-short I had to change out the HO's panel at his expense. More work and more $$ for me.;)
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You weren't working on the existing panel. I would have added a sub-panel and told the inspector that it wasn't within the scope of the work being done to change out the existing panel :D
 
Hendrix said:
You weren't working on the existing panel. I would have added a sub-panel and told the inspector that it wasn't within the scope of the work being done to change out the existing panel :D
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I changed out the whole breaker panel and made the whole installation right and safe. Installing a sub-panel onto something that was already botched up was not an option. Besides, I got paid for the work anyway.
 
LarryFine said:
I got the impression from the OP that this was for an existing panel. Why plan for tandems in a new installation?
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The op didn't say either way in the question so I was busting your chops. :cool:

I'd install a 40/60 panel in a new install if I had that many circuits. All the non afci circuits could go on the tandems rather than installing a sub panel.

OMG he's going to use.......TANDEM BREAKERS! :roll: :D
 
iwire said:
So if I have a 40 circuit 200 amp panel I don't not have to be concerned with the total load only that it will hold 40 breakers?
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This is the statement I was referring to...

Their is no limit to the number of breakers. It's based on the load.
However most panels don't exceed 42 as of now.
Click to expand...

I didn't say you don't have to be concerned about the load. If you are deciding how many breakers can fit into a panel the load has no relevance.
 
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