My breaker panel

[gordon21]

Who decides if you can put in a tandem breaker? The mfgr or the electrical inspector? I have never noticed a sticker in a box mentioning tandems being allowed or not. I always thought you could add them anywhere in the stack. Please explain the logic of why they have to be in certain places.

 

[schmism]

tandams? like "half size" breakers... or a single breaker with 2 110v circuts...

i thought it was simply a design issue. some support them, other dont.

 

[gordon21]

The width of a normal breaker for that brand (about1"), but is has two circuits and two trip levers that are not connected. You are still pulling from only one leg of power. Each half of the tandem will give you 120v. You cannot combine them to get 240v like you can with a full size 240v breaker that is 2" wide. That kind pulls from both legs, thus the 240v.

 

[swampvol]

The GE panels have the pins at the bottom of the bus bar that allows you to plug in th 1/2 inch GE breakers. The panels are usually labeled 20circuit/30max....30circuit/40 max exc. Homeline doesn't, but you can buy the 1" sqare-d tandem breakers for it.

If your bus has 20 1'" spaces, and your cover has 24 ko's and the enclosure is labeled 24 circuits, then chances are, as Bones said, someone swapped the guts out and took it back.

I doubt the inspector will even notice, as long as the panel cover fits snug, and there are no open ko's in the panel. Even if he did I really wouldn't think he would say anything unless he feels that down the road it might lead someone to believe that there are the extra spaces in the panel.

 

[AlanB]

The width of a normal breaker for that brand (about1"), but is has two circuits and two trip levers that are not connected. You are still pulling from only one leg of power. Each half of the tandem will give you 120v. You cannot combine them to get 240v like you can with a full size 240v breaker that is 2" wide. That kind pulls from both legs, thus the 240v.

Actually, on my GE, the tandem "offsets" and you do get 220v on the tied breaker that is only taking one place (although you loose 1/2 a place on the first one.)

My Electrician thought they would only pull 110 when we first went to install them, so I returned them and got normal 2" tied breakers saying they would only pull off one leg.

Then when I went to add more, I thought as I was down in the "tandem" range of my box, I would go ahead and use tandems and save some space, only to realize that you have to offset them, and by offsetting, you are picking up both legs, therby having 220V.

To the OP, look at the bottom of your box, and see if the buss bar looks different at the bottom 1/4 or so of your box then the top.

I think this is one of those things that all the manufacturerers do just slightly different. I cannot picture an electrical inspector failing an installation installed IAW a big name manufacturers instructions.

 

[Inspector507]

bones1,
If you bought a panel labeled as 24 circuit, that's what it should be, not a 20 circuit. The HOM20M100C does not allow tandems to be installed. 20 full size breakers max. The HOM24M100C is 24 full size.
But to answer your first question, it probably would pass inspection here in my area.

Call the inspector and tell him your situation...

Probably the best thing.

Who decides if you can put in a tandem breaker? The mfgr or the electrical inspector?

UL has standards that limit the number of breakers allowed.


There are actually two types of tandem breakers. CTL listed and non-CTL listed. The CTL stands for "Circuit limiting", meaning there is a rejection tab on the breaker that limits the placement to specific spots of the breaker IF they are allowed. The non-CTL listed tandems have a label affixed saying they are to be used for replacements of existing breakers only. They do not have the rejection tab.

 

[woodlot]

Gordon - On a square D panel there will be a sticker on the inside of it that will give you a head-spinning amount of information. torque spec's, wire capacities, bonding screw placment, tandem breaker information including placement, and more.

I only use square D panels so re: other brands all bets are off. The last square D panel I put in was a homeline 200amp that allowed tandems on the bottom few spaces only.