Question about circuit breakers

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zam

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On the attached photo, can you please explain what I am looking at when it comes to circuit breakers (1,3), (2,4) and 6. Thank you.
 

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Position 1 and position 3 connect to opposite sides of the 120-0-120 bus.
That means that a full sized two pole breaker in positions 1 and 3 can supply a 240V load.
Instead the two positions hold an assembly known as a quad that can supply two independent 240V circuits.
Each circuit must contain one pole fed from each of the two bus stabs.
The most convenient way to set this up is to use positions A and D for one circuit and positions B and C for the other.
The label shows that each pair has a common trip, and the handle ties insure that manual operation also affects both poles at the same time.
Quads are generally available with both independent trip, both common trip, or one of each. And the two circuits need not have the same amperage.
The sum of the two amperages must not exceed the allowable amperage for a single bus stab.

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AKA tandem, piggy-back, cheater or half-size breakers. You have four 240v circuits. Two are 20 amp, and two are 30-amp. The metal parts are to turn off both poles of the breaker should one be manually turned off or if one of them opens for an overload/overcurrent it will take the other one out with it.
 
480sparky said:
AKA tandem, piggy-back, cheater or half-size breakers. You have four 240v circuits. Two are 20 amp, and two are 30-amp. The metal parts are to turn off both poles of the breaker should one be manually turned off or if one of them opens for an overload/overcurrent it will take the other one out with it.
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But the handle ties alone do not provide an effective common trip. That requires internal components!

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GoldDigger said:
But the handle ties alone do not provide an effective common trip. That requires internal components!

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Actually, those shown are listed as Common Trip, says so right on the front too. On some Quads, the inner two poles will be common trip, the outer two are not. In order to be listed as those are shown, the breaker mfr must demonstrate to UL that if one pole trips for any reason, the other pole opens. To make those quad arrangements work, the handles, if moved rapidly, will go into a Tripped position, which is something you can't do with regular breakers. So when one pole trips, it jerks the handle on the other pole rapidly and it trips too.

What you CANNOT do is to buy your own 1/2 space "twin" breakers, mount them side x side and buy the handle clips separately, then use them as common-trip 2 pole breakers. You can buy the clips, but ostensibly only in MWBC situations for the purpose of turning both circuits off together for maintenance purposes, ala dishwasher/garbage disposal feed to an under counter duplex recep.
 
electricalist said:
If I remember they also won't fit in the last ___ spaces of the panel?
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Depends on the panel, some can take them in all space, some can't. Usually the restricted spaces where they don't fit are in the first spaces. You can also get some configurations that have no 'rejection tab' and will physically fit in any spaces but may not be legitimately listed for those panels.
 
The 20A could be supplying MWBCs; the common TRIP isn't required, but the common DISCONNECT is. I suppose the 30A could also, but I'm not accustomed to 30A 120V circuits.
 
BR quad breakers. Not all of them have common trip FWIW, these do as they are listed for that. Required for 120/240 circuits.
 
mbrooke said:
Also breaker number 5 looks like a Siemens/Murray breaker. If so changed it out for a CH BR :thumbsup:
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#7 says T&B on it as well. Not sure what panels those are listed for other then a T&B panel of course, or should I say if you need a breaker for a T&B panel today what is listed to go into it?
 
Tandems and Quads were a favorite of the mobile and manufactured home industry.

Haven't really been around too many new ones lately since AFCI requirements have expanded to nearly everything in the house to see how they are handling that these days. I think you still see some Quads for 240 volt loads but there isn't much in the house anymore that can go on a single pole tandem or half-size as AFCI protection is needed on most of them.
 
kwired said:
#7 says T&B on it as well. Not sure what panels those are listed for other then a T&B panel of course, or should I say if you need a breaker for a T&B panel today what is listed to go into it?
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I stick the stray T&B breakers I come across in BR panels. If I encounter a T&B panel I use BR. I know the listing nazis won't like that but you can ask if I care. :cool:
 
mbrooke said:
Might be listed, but I assume its not unless proof can be shown. Old vid, seen many times, but still gets the point across :thumbsup:


https://www.youtube.com/watch?v=Z9hdyYeh4KY
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What point? breakers listed or classified for a specific panel sometimes arc at the bus connection also:happysad:

If anything it shows how much more superior bolt on breakers might be:happyyes:

Of course you still need to torque the connection properly.
 
kwired said:
What point? breakers listed or classified for a specific panel sometimes arc at the bus connection also:happysad:

If anything it shows how much more superior bolt on breakers might be:happyyes:

Of course you still need to torque the connection properly.
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So your saying the same would have an equal chance of happening with GE breakers in there?
 
mbrooke said:
So your saying the same would have an equal chance of happening with GE breakers in there?
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I'm saying any breaker that physically fits in there can develop a bad connection, including the ones that are listed to go in there. So answer to your question is yes.

Even higher dollar QO and CH breakers do that sometimes, and nothing interchanges with those unless it was specifically made to fit (and probably is classified).

I have also seen on occasion an I-line breaker do that. Things just get old and fail sometimes.
 
kwired said:
I'm saying any breaker that physically fits in there can develop a bad connection, including the ones that are listed to go in there. So answer to your question is yes.

Even higher dollar QO and CH breakers do that sometimes, and nothing interchanges with those unless it was specifically made to fit (and probably is classified).

I have also seen on occasion an I-line breaker do that. Things just get old and fail sometimes.
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Sure- but then why does square D issue these warnings if the probability is equal?


http://static.schneider-electric.us/docs/Electrical Distribution/Load Centers/0106BR0502.pdf
 
mbrooke said:
Sure- but then why does square D issue these warnings if the probability is equal?


http://static.schneider-electric.us/docs/Electrical Distribution/Load Centers/0106BR0502.pdf
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Marketing hype. And I say this as a person that mostly prefers to install Square D as well.

Square D is most of what I normally see, seen many failures of bus to breaker connections on them. Seen very few "classified" QO breakers in my lifetime as well, never seen one fail, but then haven't seen enough of them to have a good chance of seeing that happen either.

Plug on breakers in general are going to have a risk like that. Bolt on - no so much if tightened properly, but over time connections still can get compromised.
 
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