Reuben's Home Inspection Blog

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Cheater Breakers

cheater breakers highlightedWhen an electric panel is filled with standard circuit breakers and more circuits need to be added, the solution is sometimes to install tandem breakers.  These circuit breakers allow for two circuits to be installed under one space, so they're often call cheaters.  A few other terms that I commonly hear are duplex, twinner, half-height, half inch, and double.

Is this really cheating? No.  This is a perfectly acceptable practice... but there are several rules that need to be followed to make the installation correct.  When these rules aren't followed, I suppose you could call it 'cheating'.   Today I'll share what I look at when inspecting tandem breakers.

The model of the panel

The model or part number of the electric panel will typically give away whether or not the electric panel is designed to accept tandem breakers or not, and how many can be used.  Here are a few examples:

  • HOM20M100C  = 20 spaces for standard circuit breakers.
  • QO13040M200C = 30 spaces for standard circuit breakers, and will accept a total of 40 circuits - that means 10 tandem breakers can be used at this panel.
  • E0816ML1125S = 8 spaces for standard circuit breakers, and will accept a total of 16 circuits - that means all 8 spaces accept tandem breakers.
  • BR1224L125V1 = 12 spaces for standard circuit breakers, and will accept a total of 24 circuits - that means all 12 spaces accept tandem breakers.

I think it's easy enough to see the pattern here.

A diagram inside the panel

The wiring diagram inside the panel is the best way to determine if tandem breakers are allowed, and if so, exactly where they're allowed.  In the photo below, which I used in my blog about double tapped circuit breakers,  you can see that the top four spaces allow only full size breakers, while the bottom eight slots allow tandem breakers.

Panelboard diagram

Here's another panel diagram - this panel allows the use of tandem breakers in four locations.

Panelboard diagram 2

And another - this panel doesn't allow any tandem breakers.

Panelboard diagram 3

And another - this panel allows tandem breakers in the bottom ten spaces only (11-20 and 31-40).

Panelboard diagram 4

Other Things To Look For

If the diagram inside the panel is missing or isn't clear, there are several other ways to help determine if tandem breakers can be used in a panel.  One simple way is to look for the maximum number of circuits allowed.  In the photo below, you can see that only 20 circuits are allowed at the panel.  This panel had 20 full-size spaces, so tandem breakers weren't allowed.

Max Poles

If the label is missing, another way to determine the maximum number of circuits allowed is to count the number of terminals for the neutral wires.  For instance, if there are 23 terminals present for neutral wires, the panel is probably designed for 20 circuits.  This is not a hard and fast rule though - some panels may have 40 neutral terminals present, yet only be designed for 20 circuits.  In the photo below, there are a total of 23 terminals; 1 for the main neutral wire coming in to the panel, 1 to bond the panel, 1 to ground the panel, and 20 more for the neutral wires.  This panel is designed for 20 circuits.

Neutral bar

Another trick is to just look at the shape of the bus bars, if they're visible.  Bus bars that are designed to accept tandem breakers will often have a slightly different shape.

Bus bars

In the photo below you can see that tandem breakers will often have a different design than standard breakers, which prevents them from being installed in locations where they shouldn't go.

Tandem vs standard breaker

Tandem vs standard breaker 2

The manufacturers make them this way in an effort to prevent people from using them in an improper manner - but this doesn't stop everybody.  In the photo below, you can see how someone broke the bottom of a breaker to force it in to a place that it wasn't designed for.

Broken tandem breaker

If a circuit breaker sticks out from the rest of the circuit breakers, or 'stands proud', it probably doesn't belong.  This particular panel didn't allow tandem breakers.

Proud circuit breaker

When I find improper installations like this, I always recommend having an electrician come out to make repairs.

Oh, and for the record -I've been saying 'electric panel' this whole time, but a more technical term would be 'load center.'

Reuben Saltzman, Structure Tech Home Inspections

        

Comment balloon 14 commentsReuben Saltzman • August 17 2010 07:00AM

Comments

Excellent informative post Reuben.  I know nothing about electrical work, but this all makes sense.  Thanks.

Posted by Roger D. Mucci, Lets shake things up at your home today! (Shaken...with a Twist 216.633.2092) almost 8 years ago

Good information for home owners. Thanks for sharing.

 Blooming for home buyers.

Posted by Roy Kelley, Roy and Dolores Kelley Photographs (Realty Group Referrals) almost 8 years ago

Thanks Roger - this would have been a tough blog to write without being able to use photos.

Don and Roy - thanks for the comments, and thanks for re-blogging.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 8 years ago

I did not think about counting th terminals for the neutral wires. Learned something new.  Thank you

Posted by Stanley Stepak, Realtor - Avon Lake, Avon, Bay Village, Westlake, (Howard Hanna - Avon Lake, OH) almost 8 years ago

Hi Reuben, great info and summary!  As always, very informative.

Posted by Dale Ganfield almost 8 years ago

Great information.  Around here the common term is "mini breaker".

It sure is nice to see a panel you can actually read.  Most times  the labels are missing or deteriorated beyond recognition.   Your posts are outstanding.

Posted by Jim Mushinsky (Centsable Inspection) almost 8 years ago

Hi Stan, glad I could help.

Dale - thanks.  I always learn a little something here and there as I write these too.

Jim - 'mini breaker', huh?  That's one I've never heard.  

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 8 years ago

Great Post! I like how they jammed that breaker onto the bus bar. OUCH!

Posted by Mike Gillingham (Eastern Iowa Inspection Services LLC) almost 8 years ago

Thanks Mike.  I'll bet the back of that breaker looked just like my photo of the broken breaker.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 8 years ago

Looking at this post was just like talking to my favorite electrician.  He doesn't mind when I come down to the circuit breakers and discuss various aspects of not only mine but other clients' panels. 

If I can find a reasonable property to call you on, I certainly will.  You are very astute.  Thanks for a great post. 

Posted by Suzanne McLaughlin, Sabinske & Associates, Realtor (Sabinske & Associates, Inc. (Albertville, St. Michael)) almost 8 years ago

Thanks Suzanne, hopefully this is one that people will bookmark and refer back to :)

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 8 years ago

Great post Reuben.  Very educational.   When we see a "double tap" - we typically ask that it is corrected.

Posted by Alan Bruzee (Long & Foster Real Estate, Inc.) almost 8 years ago

We call it "double lugging" out here.  But it all looks way too complicated for me.  This is why I always recommended a great home inspector!!  I don't like screwing in a lightbulb . . . so I stay away for electrical panels.

Posted by Carla Muss-Jacobs, RETIRED (RETIRED / State License is Inactive) almost 8 years ago

Alan - double taps are definitely standard procedure to ask for repairs on.

Carla - usually "double lugging" means the same as "double taps."  I wrote a blog about those here http://activerain.com/blogsview/1441465/how-to-fix-double-tapping-at-circuit-breakers . Is that what you're thinking of?  If screwing in a light bulb isn't your thing, it would be very easy to get these two confused.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) almost 8 years ago

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