Thoughts on tandem breakers?

[Jarrett Vibert]

A subpanel fed off the main panel would work,double taps off the meter can will not...

x2...

I seriously can't put a number on the amount of services I've upgraded and/or installed new, and I have never heard of a "double tap" meter base. A sub-panel is the cheapest/easiest solution.

FWIW... "most" (notice the quotation marks around "most" to note it's definition, ie: not all) service feeders from the street are sized for 200amp.

PS: As an electrician, I would never use a tandem breaker in my own home. I have installed them for customers as a cost saving measure though.

[Phil Thien]

PS: As an electrician, I would never use a tandem breaker in my own home. I have installed them for customers as a cost saving measure though.

Any specific reasons for avoiding them?

[Mike Cutler]

Phil

I have tandems in my main service panel. However, the panel is code approved and rated for them according to all of the documentation on the door of the panel.
The panel manufacturer has specific instruction for how many, and where in the panel they can be placed. There are also specific tandem breakers, id'd by part #, allowed in specific slots.
I'm assuming that the issue with precluding the indiscriminate use is the shared neutral return. Just an assumption though. ???

[Phil Thien]

I'm assuming that the issue with precluding the indiscriminate use is the shared neutral return. Just an assumption though. ???

I lost you there. Does a tandem breaker imply a shared neutral return?

I thought tandem breakers were simply two breakers in one package, and they were on the same leg.

Or are you saying people are using a single neutral return on these? Wouldn't that be the same as using a single neutral return on two separate breakers on the same leg?

That would be a recipe for a house fire, wouldn't it?

BTW, any good reading suggestions? I've got "Wiring Simplified" and a PDF of the 2008 NEC.

I know it sounds weird but these tell you what to do. It would be interesting to read "What not to do, horror stories from electricians."

[Steven DeMars]

SUB PANEL is always the preferred method. Safety and simplicity . . .

Steve

[Phil Thien]

SUB PANEL is always the preferred method. Safety and simplicity . . .

Steve

I know this sounds crazy, but...

A subpanel requires two new breakers, a new panel, and wire connecting the two. It seems like you'd be adding multiple possible points of failure to avoid adding a tandem breaker.

What about a tandem makes it worth going through all that extra stuff to avoid one?

BTW, I'm not challenging anyone, just trying to understand the problem with tandem breakers.

[Mike Cutler]

I lost you there. Does a tandem breaker imply a shared neutral return?

I thought tandem breakers were simply two breakers in one package, and they were on the same leg.

Or are you saying people are using a single neutral return on these? Wouldn't that be the same as using a single neutral return on two separate breakers on the same leg?

That would be a recipe for a house fire, wouldn't it?

BTW, any good reading suggestions? I've got "Wiring Simplified" and a PDF of the 2008 NEC.

I know it sounds weird but these tell you what to do. It would be interesting to read "What not to do, horror stories from electricians."

Phil

I have seen, and still see, in my panel a 3 conductor 12awg. Black, Red, and White connected to a set of tandem 20 amp breakers. This means that both 20 amps breakers are sharing the same return path, in sync. I'm assuming that this meets, or at least met, code in 1979 when the panel was installed. Whether or not it still does only our licsensed friends here on the board can say.
Do I think my configuration is unsafe? No not really. One 20 amp supplies the GFCI protected receptacle in the bathroom. The other supplies the bathroom vent fans and lights.

[Phil Thien]

I'm assuming that this meets, or at least met, code in 1979 when the panel was installed. Whether or not it still does only our licsensed friends here on the board can say.

Yeah, it would be interesting to hear what the electricians say.

My guess: It wasn't compliant back in 1979, either.

At least you are aware of it, though.

[John McClanahan]

If I were to read "24 breakers, 24 circuits", I would take it to mean 24 slots. I may be wrong there. If the breaker box can not use tandem breakers, they probably will not snap in place, thus preventing their use.

My point in my first reply was to find out what your options are now, and not wait until you need it.

As for the shared neutral, don't let 2 breakers on the same hot leg share 1 neutral wire, as it can be overloaded.

John

[Rollie Meyers]

People keep bringing up using a twin breaker, the OP's PANEL IS NOT LABELED TO ACCEPT TWINS!!!!! Which makes it a foolish act to violate a manufacturers instructions, per NEC 110.3 (B)

(B) Installation and Use. Listed or labeled equipment
shall be installed and used in accordance with any instructions
included in the listing or labeling.

This is a copy & paste from the 2008 NEC.


IMO, why a 24 space loadcenter is full size breakers only I don't know Siemens did make a 30 space 100A main breaker loadcenter & would have been a better choice to use in the original install, but that is a moot point since it's a done deal........

I hate twins & was furious when Cutler-Hammer introduced a twin for their CH loadcenters years ago.

[Phil Thien]

I hate twins & was furious when Cutler-Hammer introduced a twin for their CH loadcenters years ago.

But why?

It seems lots of pros despise them, I'd just love to know why.

[Rollie Meyers]

They are the mark of a poor install if done "new", I recognize their value in service & remodel work, it's one of many reasons that prefer Bolt-On panels,never have to worry about someone stuffing any twins in a panel built for Bolt-On breakers. To put it simple, twins are like trying to stuff 10 pounds of manure in a 5 pound bag.

[Adam Strong]

But why?

It seems lots of pros despise them, I'd just love to know why.

I am with you Phil... If a panel is rated for a tandem breaker and the breakers are code approved, there should be no issue. I have a Siemens 200 amp panel in my home with 20 slots. The panel is rated for use with certain listed tandems up to 40 circuits. This means I could run all tandems if needed and it would be manufacturer and code approved. I see no reason not to use them in this case. Though in your case, Phil, your panel not being rated for tandems means your only options are either a new larger main, or a sub panel.

[Phil Thien]

Though in your case, Phil, your panel not being rated for tandems means your only options are either a new larger main, or a sub panel.

You forgot option #3: Being happy with the tools I have.

[Phil Thien]

They are the mark of a poor install if done "new", I recognize their value in service & remodel work, it's one of many reasons that prefer Bolt-On panels,never have to worry about someone stuffing any twins in a panel built for Bolt-On breakers.

Fair enough.

To put it simple, twins are like trying to stuff 10 pounds of manure in a 5 pound bag.

I'm more accustomed to paying for five pounds and getting two and a half.