Anything "wrong" with tandem breakers?

[5mall5nail5]

I have a 30 position panel that is almost filled. I have 3 blanks open. Two will be immediately used for a 240v circuit. The remaining is going to be used for a 120v 20A circuit. Is there any reason to NOT use tandem breakers? I would love to put in a 40 - 42 position box but its a bigger project than I want to do right now.

Thanks,
Jon

 

[porschedude996TT]

I have them in my shop sub-panel and have no problems.

 

[rsanter]

only problem I know is that if you nearly double the plugs or connections made in the pannel you can seriously overload that pannel.
of course if you are smart enough to know not to do that....no problem.
I use them and they are really convieient

bob

 

[shocksandstrutz]

i am going to add two TANDEM BREAKERS to my main panel so I can finish my basement and add an attic fan.....I should be plenty good with power then for whatever I need.

 

[RickP]

I have a 30 position panel that is almost filled. I have 3 blanks open. Two will be immediately used for a 240v circuit.

Tandem breakers are fine, but I'd be worried about future expansion with no more blanks left in your panel. Have you already run the wires for the 240v circuit? Any chance you could make that a circuit for a subpanel instead and run the 240v circuit from the subpanel?

 

[porschedude996TT]

only problem I know is that if you nearly double the plugs or connections made in the pannel you can seriously overload that pannel.
of course if you are smart enough to know not to do that....no problem.
I use them and they are really convieient

bob

Overload or pop a breaker, no harm no foul.

It all depends on how it is executed.

When I did the calculations for my house using the values in the NEC, my 2,000 ft. house, without A/C, natural gas stove, oven, water heater, clothes dryer, I came up with maybe 43 amps. I was looking at adding my shop with a 100 amp sub-panel and needed to know where I stood. Most of the loads in a residential house in my area are real low. Houses with 200 amp panels are common and having a breaker for every room’s receptacles.

Breakers protect wiring, main breakers protect the panel. If you have problems with load balance on a panel, then it is a design problem and not a hazard. It is considered a nuisance breaker trip.

 

[SlowAl]

Does your panel support tandem breakers? Some or all of the bus stabs need to be notched to allow the breakers to even fit.

Instead of using up those two slots for the 240v circuit, maybe you could use them to feed a small subpanel to give you some more room?

 

[1/2 Cup]

Does your panel support tandem breakers? Some or all of the bus stabs need to be notched to allow the breakers to even fit.

Instead of using up those two slots for the 240v circuit, maybe you could use them to feed a small subpanel to give you some more room?

I would recommend the installation of a sub switchboard as well, not that there is any thing wrong with tandem breakers, but this would potentially allow you to reefed some of the existing circuits to the sub panel, provided that the sub mains and breaker are correctly rated this would free some space in your existing switch board as well.

 

[5mall5nail5]

I did consider a sub panel but I think for right now I will just have a full board (one slot open) and if it doesn't take a tandem breaker I'll have to replace the panel when I get that new requirement for a circuit.

 

[sberry]

Great to move light circuits, other lightly loaded ones to.

 

[Norcal]

When one cannot or will not change a too small panel, a twin breaker is the only economical choice left, I personally just think they are bad form in a new installation.

 

[theoldwizard1]

Does your panel support tandem breakers? Some or all of the bus stabs need to be notched to allow the breakers to even fit.

If you have to modify the bus, then it was not designed for tandems and using them could cause a problem or at least void your homeowners insurance.

 

[theoldwizard1]

only problem I know is that if you nearly double the plugs or connections made in the pannel you can seriously overload that pannel.

Overload what ? The bus bars ? They are protected by the main breaker.


The real problem is lack of bus bar connections for neutrals and grounds. I added 4 tandems to my daughter's Square D QO load center and had to double up wires under some screws.

BTW, not all QO load centers are created equal ! Older models will not accept new tandems. The old tandems are available (not everywhere) , but are more expensive.

 

[theoldwizard1]

Great to move light circuits, other lightly loaded ones to.

Microwave, garbage disposer, dishwasher. Modern versions of these appliance are not even close to 15A even though it recommended to have a separate circuit for each.

 

[SlowAl]

If you have to modify the bus, then it was not designed for tandems and using them could cause a problem or at least void your homeowners insurance.

Yeah, I should have been more specific about the panel already having the notches from the factory, not whipping out the dremel and doing it yourself.

 

[Charles (in GA)]

If the part number of the panel is something that has the numbers 30/40 in it, then it is designed to accept ten tandem breakers, usually the bottom five stabs. On some brands, Siemens, Sq D Homeline, Murray, CH/Bryant panels, and a few others, the stabs are notched to accept the tandems. On Sq D QO panels, the positions that accept the tandems have a recess that allows the protrusion on the bottom of the tandem to fit into it. On GE there is a funny U shaped stab welded to the bus bars in the places where the tandems will fit (in addition to the regular stabs).

There are tandems that will fit panels that do not have notched stabs. These are only allowed to be fitted to panels manufactured before a certain date, sometime in the 1980's, before the code changed.

Here is a Square D QO 30 space, 40 circuit panel that accepts ten tandems.

Here is a depiction of the notched vs un-notched stabs and the limiting vs non-limiting tandem breakers.

Here is a diagram on a door that shows where the the tandems are allowed to be installed in the panel.

Here is a Square D QO tandem breaker. Note the hump on the bottom side of the breaker (the breakers are inverted, the bottom is up in this pic). If the panel will NOT accept tandems, this hump will NOT fit and the breaker will NOT snap down, if the panel DOES accepts tandems, there is a recess that lets the hump fit in place and the breaker DOES locks down on the stab.

Charles

 

[pattenp]

wyliesdiesels, be careful responding/quoting spam post. See GJ rules... http://www.garagejournal.com/forum/showthread.php?t=166218

 

[taumac]

I glad to hear that. My house built in 85 and for some reason its a small panel and was wired with 5 tandem breakers. I added 4 circuits for garage 3 20 amp and 1 40 amp. I wanted to find 3 more of the same tandems but couldnt at time. I did happen to find them after the fact so if need a circuit and can always put out the single for a tandem.

 

[wyliesdiesels]

wyliesdiesels, be careful responding/quoting spam post. See GJ rules... http://www.garagejournal.com/forum/showthread.php?t=166218

Whoops! Didnt know that! Ive deleted it!......Though I honestly thought that it was possibly a legitimate comment written in a different language! U just never know!

 

[timtim2008]

anyone use QUAD breakers?

 

[djb2]

anyone use QUAD breakers?

Errmm, that's typically called a 'triplex' breaker.

It spans two stabs to pick up both legs of a 240V circuit, plus provides two independent 120V circuits.

They are pretty common on Murray/Crouse-Hinds/Siemans panels, with many combinations available and priced reasonably ($20 vs. $12 for duplex, when they are essentially a pair of duplex breakers). They are specialty items and priced accordingly for other brands.

One point not covered above is that many panels don't have wiring space or knock-outs to accommodate more than a few half-width (duplex or triplex) breakers.

 

[Norcal]

Errmm, that's typically called a 'triplex' breaker.

It spans two stabs to pick up both legs of a 240V circuit, plus provides two independent 120V circuits.

They are pretty common on Murray/Crouse-Hinds/Siemans panels, with many combinations available and priced reasonably ($20 vs. $12 for duplex, when they are essentially a pair of duplex breakers). They are specialty items and priced accordingly for other brands.

One point not covered above is that many panels don't have wiring space or knock-outs to accommodate more than a few half-width (duplex or triplex) breakers.

Who calls it a "triplex", it's a quad? It has 4 breaker poles not 3.

 

[sberry]

My folks home is a good example, full panel, small power use and in reality could combine several circuits, not only are they not used at the same time but not really used at all, probably half a dozen with no load at all.

 

[theoldwizard1]

My folks home is a good example, full panel, small power use and in reality could combine several circuits, not only are they not used at the same time but not really used at all, probably half a dozen with no load at all.

The flip side. When my Dad bough his cottage "up north", it had a 60A fuse panel. 4 - 15A fuses ! I don't recall how the well pump was wired. Maybe it was 120V ?

During remodeling, he added a new 100A load center on the other side of the house and the old "main" became a sub.

 

[pattenp]

The breaker pictured is a Triplex. One 2pole and two 1pole. A quadplex is two 2pole.

http://www.homedepot.com/catalog/pdfImages/a2/a2616c67-a4b5-4001-9e69-5e7fd120598a.pdf

Who calls it a "triplex", it's a quad? It has 4 breaker poles not 3.