Tandem breakers...what's the catch?

[Quattro]

Hey all,

I'm putting in a sub-panel tonight so I can run a few more circuits to the kitchen. I bought a SquareD QO panel that says it can hold 6-12 circuits. Now, I count 8 slots in the panel, but realize they want 2 left open for some reason.

Question is, are there any drawbacks to using tandem breakers? These are the half-size breakers molded into the same "shell", and only take up 1 space. They make sense, but I just don't know what the negatives are...if any.

Anyway, thanks for any info!

 

[cibula11]

I'm in a similar situation. If you find anything out let me know. I have 3 installed on my current panel and I would like to add 2 more to free up an extra two spaces to run a 220v. I have heard that there is info. on the panel that says what you can do, but I looked and my panel didn't have any info.

 

[Kerrylib]

I think the 2 slots to be left open are to install a double pole breaker that will work as a shutoff for that subpanel. Flip that one and kill the whole box.

Here's the Square D catalog info on QO breakers. Says that tandem breakers can only be installed in certain positions on the panel.
Best to understand exactly how mfgr states they can be used

http://ecatalog.squared.com/techlib/displaydocument.cfm?id=0730CT9801&action=view

From what I've heard, the smaller breakers have less room to dissapate heat and can therefore fail more easily. If the box isn't sized for the extra circuits, you can exceed fill capacity, run out of neutrals, etc.

Seems that they are a way to squeeze just one more circuit into the older installations so you don't have to upgrade the entire service.

 

[JoeD]

There are no drawbacks when they are installed and used properly.

 

[bobthebuilder]

hi everybody,

i am new to this forum, my question is:

we have a 200 A breaker box, we put in a 125 A breaker to go to subpanel
in that subpanel we 5 breakers installed
1 60A breaker to handle 2ton air handler
1 60A breaker to handle 4 ton air handler/heatstrip
1 60A breaker to handle 4 ton air handler
1 40A breaker to handle 4 ton heat pump
1 30A breaker to handle 2 ton heat pump

the problem we have is when we turn on the 4 ton airhandler/heatstrip it pops the breaker.

my question is can i increase the 60A breaker to a higher one or do i need another 200A breaker box to take care of all the breakers in the subpanel?
thank you for your answers and help.

 

[glennjanie]

Hey there Bob, Welcome to the Forum:
You have a pretty good load in that subpanel and I don't know how much it is rated for. What I do know is, if you go to a higher amperage breaker for the heat strip you will also need larger wire to feed the heat strip. There are others on here that can take you much deeper into the subject than I can.
Glenn