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Easy sub panel question

nicobkn

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Oct 1, 2009
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184
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Montreal CAN
Hello guys

Planing on installing a sub panel in the garage. I just wanted to clarify something. When talking about 8/16 Circuit sub panel, does that mean 8 double brakers or 16 single brakers?

Thanks a bunch
 
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malibu101

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Walnutport PA
I've seen an 8 single-pole breaker spaces panel be labeled and listed as such if used with 8 tandem breakers for a total of 16 single-pole breakers.

In other words, if using "normal" single pole breakers you would have 8 spaces. If using two pole breakers for 240V you would only have room for 4 double pole breakers.
8 tandems = 16 single pole breakers allowbale/max.
 

Norcal

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Don't get stingy w/ panel size, it's always nice to have more space in the future.
 

silver2000

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Falmouth, Massachusetts
It's not always meaning tandem breakers, I have a panel thats 20/40 Square D HOM and does not accept Tandem. Technically each breaker will accept two wires on it which is where the doubling comes from. Some are allowed by code (surge suppression box) and I think perhaps a doorbell. I know in most cases its not code legal and I always avoid it. I just added a 20 circuit and would always go bigger since the cost is literally peanuts. Like an 8 circuit costs $40 and a 16 is $47. Most of the time folks go smaller if they can't fit a larger box but it is definitely a better move int he long run to avoid another panel.
 

joe_padavano

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Verify what the panel really is. All panels I've ever used (GE, Square D, Cutler Hammer) use the terminology like 20/40 or 8/16 to mean the number of FULL SIZE (ie 1" wide) breakers and the number of half size (1/2" wide) breakers. In other words, an 8/16 panel will hold eight 1" wide breakers or sixteen 1/2" wide breakers. This has nothing to do with single or double breakers.
 

pattenp

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Virginia - USA
It's not always meaning tandem breakers, I have a panel thats 20/40 Square D HOM and does not accept Tandem. Technically each breaker will accept two wires on it which is where the doubling comes from. Some are allowed by code (surge suppression box) and I think perhaps a doorbell. I know in most cases its not code legal and I always avoid it. I just added a 20 circuit and would always go bigger since the cost is literally peanuts. Like an 8 circuit costs $40 and a 16 is $47. Most of the time folks go smaller if they can't fit a larger box but it is definitely a better move int he long run to avoid another panel.

This is news to me. The Square-D Homeline load centers I've seen that are listed as 6/12, 8/16 and so on, the numbers represent the number of circuits based on the number of breakers that can be installed in the panel. Not based on the number of wires that can be inserted in the breaker. I don't know what model 20/40 Hom panel you have but the ones I'm familiar with will take up to 20 tandem breakers.
 

silver2000

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Falmouth, Massachusetts
I was pretty bummed actually. I really just needed a few more circuit and thought I would go tandem only to find this out. Most of their HOM line does not accept Tandem. They design the breaker so that it will not even fit. Though I know guys break off the tab so they can still get them in there, but that's not something I would do. Sounds like bad news. I wish my house had the QO (Quick Open) Square D line but alas my HOM has sufficed so far and now with 3 subs I won't be switching soon.
 

Charles (in GA)

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Verify what the panel really is. All panels I've ever used (GE, Square D, Cutler Hammer) use the terminology like 20/40 or 8/16 to mean the number of FULL SIZE (ie 1" wide) breakers and the number of half size (1/2" wide) breakers. In other words, an 8/16 panel will hold eight 1" wide breakers or sixteen 1/2" wide breakers. This has nothing to do with single or double breakers.

This is true, and to add to it somewhat. The "half width" breakers (1/2" wide for Siemens, Square D Homeline.... and 3/8" wide for Square D QO panels) are usually paired together (as in two separate breakers riveted together, but with separate handles, not connected) because this is about the only way to attach them to the stabs in the panel. In the case of GE "half width" breakers, they use a special clip that attaches to a protrusion on the stab, so they are individual 1/2 inch wide breakers, and they even make 1/2 wide filler plates to cover the remaining part of the opening in the panel front.

Square D QO breakers are only 3/4 inch wide to start with, so their half width breakers are 3/8 inch, but always found in pairs (known as Tandems) because this is the only practical way to install them in the panel.

Charles
 
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ddawg16

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Is the garage attached or detached?

If detached...you need a main disconnect breaker in that panel if you want to use more than 6 breakers.

If the garage is attached....never mind.

Side note...I have a SD load center.....20/40 to be exact and it accepts the tandem breakers.

As Norcal said, don't get stingy....it's not so much the current loading, but more of being able to isolate ckts. Nothing worse than have about 20 things on one ckt....non of which by themselves is going to over load it....but when the breaker trips....not only is the whole string down....it can sometimes be hard to isolate the problem.

I like having a lot of breakers.....
 
OP
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nicobkn

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Oct 1, 2009
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Montreal CAN
hello everyone

thank you so much for the good feedback! I checked on homedepot.ca and found this:

12 Spaces, expandable to 24 circuits maximum with the use of QO tandem breakers

So I guess that pretty much answers my question.

*I didn't read all the replies yet, planning on doing it tomorrow.

Thanks again
 

joe_padavano

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This is true, and to add to it somewhat. The "half width" breakers (1/2" wide for Siemens, Square D Homeline.... and 3/8" wide for Square D QO panels) are usually paired together (as in two separate breakers riveted together, but with separate handles, not connected) because this is about the only way to attach them to the stabs in the panel. In the case of GE "half width" breakers, they use a special clip that attaches to a protrusion on the stab, so they are individual 1/2 inch wide breakers, and they even make 1/2 wide filler plates to cover the remaining part of the opening in the panel front.

Square D QO breakers are only 3/4 inch wide to start with, so their half width breakers are 3/8 inch, but always found in pairs (known as Tandems) because this is the only practical way to install them in the panel.

Charles

Charles,

Thanks for the clarification. I've been using GE panels exclusively on the farm, thus my knowledge of the 1" and 1/2" breakers.
 

VHF

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NW Wisconsin
I was pretty bummed actually. I really just needed a few more circuit and thought I would go tandem only to find this out. Most of their HOM line does not accept Tandem.

A 100A Square D HOM 20/20 panel won't accept tandem breakers. A 200A 30/40 panel will, but only in the bottom 5 rows (bottom 10 positions.)

With the recent NEC change to remove the maxium number of circuits allowed in a panel (was 42 prior to 2011), I would expect manufacturers to produce a 40/80 panel!

There are non-CTL (non circuit limiting) tandem breakers which will fit in any position in the panel, but they are only code-compliant when used in a pre-1968 panel. Not sure if Square D makes these as HOM may not have been around that long.
 

theoldwizard1

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SE MI
Not that I have looked inside many load center boxes, but I have never seen or heard of 1/2" breakers. Tandem, yes.

The old Square D QO tandems (QO1515 vs QOT1515) are pricey !
 

Charles (in GA)

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50 mi south of Atlanta
GE ½" 20 amp breaker

c1d2f750-e61b-460e-a8a3-4a2d22c18ef5_300.jpg


These only fit in GE panels, and only in the positions with the extra protrusions on the stab for it to snap onto.

Other brand tandem circuit breakers share the clip that fits over a regular stab, and thus have to be mated together into tandems.

Charles
 
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