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  1. #1
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    Default same gauge req'd on sq D double tap?

    Assuming the breaker is sized for the smaller wire is it acceptable for a Square D breaker (type okay for double taps) to have different wire sizes on a double tap?

    The most obvious case would be a 15A breaker with one 14 gauge and one 12 gauge wire.

    I ran across something this week that was wrong for several reasons with this possibly being one of them and it got my curiosity.

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    Default Re: same gauge req'd on sq D double tap?

    No, the wires should be the same size.

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

  3. #3
    Ted Menelly's Avatar
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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Matt Fellman View Post
    Assuming the breaker is sized for the smaller wire is it acceptable for a Square D breaker (type okay for double taps) to have different wire sizes on a double tap?

    The most obvious case would be a 15A breaker with one 14 gauge and one 12 gauge wire.

    I ran across something this week that was wrong for several reasons with this possibly being one of them and it got my curiosity.

    It has to be the same size wire. If not the pressure comes down on the thicker wire first it may not tighten down on the smaller wire securely enough causing a loose and or overheated situation.


  4. #4
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    Default Re: same gauge req'd on sq D double tap?

    Only other thing that I would add to Ted and Ricks reply is that two wire pressure plate type terminals only go from 10 to 30 amp square d QO and Hom single pole breakers. And the wire size cannot be over 10 awg. All other residential breakers are single termination box type lugs.

    Also when terminating two wires to QO and Homeline 10 to 30 amp single pole breakers ... both wires must be copper you cannot terminate two aluminum .. or one aluminum and one copper. The plate terminal is rated for copper only terminations when you terminate two conductors.

    If your terminating one conductor then it can be al or cu 14 awg to 10 awg.


  5. #5
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    Default Re: same gauge req'd on sq D double tap?

    I emailed Square D/Schneider support and was told the conductors can be different sizes.

    "There is no exception to the rule that every rule has an exception." -James Thurber, writer and cartoonist (1894-1961)
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  6. #6
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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by John Arnold View Post
    I emailed Square D/Schneider support and was told the conductors can be different sizes.
    Hi John

    I'm attaching a document that likely supports that e-mail. If you scroll down to the heading "Terminations" you find a table and explanation on the terminal ratings. It's a pdf so let it load up before navigating...sometimes your computer will lock if you get in a hurry ...

    I suspect there will still be some disagreement that you can terminate two conductors of different sizes...


    http://static.schneider-electric.us/...CT9801R108.pdf


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    Default Re: same gauge req'd on sq D double tap?

    RF,
    Same reply here...I thought I'd seen or read this at some time in the past, Good question Matt

    Q: Assuming the breaker is sized for the smaller wire is it acceptable for a Square D breaker (type okay for double taps) to have different wire sizes on a double tap?

    The most obvious case would be a 15A breaker with one 14 gauge and one 12 gauge wire.

    A: Dear Barry :

    Thanks for contacting Schneider Electric !

    If you are referring to the QO/Homline breakers you are correct.
    These have pressure plate terminations that allow for different size conductors to be used at the same time.

    Hope this helps. If you have any further questions/concerns please don't hesitate to contact us.

    Regards
    Jeff Dixon
    Square D/ Schneider Electric
    Cedar Rapids PSG Sr. Product Support Specialist
    1-888-778-2733


    mine: proper torque would be required

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  8. #8
    Ted Menelly's Avatar
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    Default Re: same gauge req'd on sq D double tap?

    Yes they have a pressure plate that may very well allow for different size wires but it is getting pushed down by a screw that only one side of the screw is pushing down on and applying uneven pressure. I am not quite sure why they say it is alright but if they do go for it. I personally would not as the thicker wire is getting the greater pressure which when you stop turning, feeling enough pressure is the same pressure on the thinner wire.

    From what they are saying you can possibly have a number 10 on one side and a 14 on the other which obviously would not be but could be.

    So the question to home inspectors is when or do you write it up or at all. I tried getting a similar answer about how many breakers could have double taps in one panel with Square D breakers. I could not get a reasonable answer for that either but that question is...what is reasonable. Monday I had a panel with 6 double tap Square D breakers. All the same size wires but it just did not read right to me. No I did not do the whole load calc or anything to that degree.


  9. #9
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    Default Re: same gauge req'd on sq D double tap?

    Barry

    I'm glad you posted that e-mail as final confirmation. The only other thing that might be beneficial is to mention that mixing the wire sizes will require attention to the size of the breaker. In other words you can't connect a 14 awg and a 12 awg on a single pole 20 amp QO or HOM circuit breaker in most all cases in residential dwellings.


  10. #10
    Roger Frazee's Avatar
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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Ted Menelly View Post
    Yes they have a pressure plate that may very well allow for different size wires but it is getting pushed down by a screw that only one side of the screw is pushing down on and applying uneven pressure. I am not quite sure why they say it is alright but if they do go for it. I personally would not as the thicker wire is getting the greater pressure which when you stop turning, feeling enough pressure is the same pressure on the thinner wire.

    From what they are saying you can possibly have a number 10 on one side and a 14 on the other which obviously would not be but could be.

    So the question to home inspectors is when or do you write it up or at all. I tried getting a similar answer about how many breakers could have double taps in one panel with Square D breakers. I could not get a reasonable answer for that either but that question is...what is reasonable. Monday I had a panel with 6 double tap Square D breakers. All the same size wires but it just did not read right to me. No I did not do the whole load calc or anything to that degree.
    If the wire sizes are correct and the breaker protection is correct for the smallest awg there is nothing to write.

    The UL listing and the manufacturer labeling for Square d allow two conductors to share a circuit breaker when connecting to 15 thru 30 amp single pole QO and HOM breakers.

    The question that is typically asked is .. "If I have a Square d panel for example a QO13040M200C how would you determine number of circuits if you use 30 single pole QO breakers with double taps in use to fill all the spaces.

    Do I have 30 circuits or 60 circuits?

    The loadcenter catalog numbering says I can have a max. of 40

    Last edited by Roger Frazee; 12-01-2010 at 01:59 PM.

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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Roger Frazee View Post
    The question that is typically asked is .. "If I have a Square d panel for example a QO13040M200C how would you determine number of circuits if you use 30 single pole QO breakers with double taps in use to fill all the spaces.

    Do I have 30 circuits or 60 circuits?

    The loadcenter catalog numbering says I can have a max. of 40
    If you had 30 single pole breakers installed you have 30 circuits. A double tap attached to one breaker is still one circuit.

    You count single poles as one circuit, a double pole breaker, or a tandem as two circuits


  12. #12
    Ted Menelly's Avatar
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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Jim Port View Post
    If you had 30 single pole breakers installed you have 30 circuits. A double tap attached to one breaker is still one circuit.

    You count single poles as one circuit, a double pole breaker, or a tandem as two circuits
    Although technically correct I never think of it as such. No matter how many breakers, I have always thought of it as how many home runs are coming back to the panel. Each wire coming into a panel that supplies a group of electric boxes or for that matter just an individual box for say an appliance I call a circuit. If you double tap every breaker in some of these large panels (single pole) you no longer have anywhere near the same load.

    That is like saying that a home that would normally have 2-200 amp panels in a garage that you could eliminate one, Of course just the single pole as we are talking about, and add a smaller panel for the extra double pole breakers.


  13. #13
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    Default Re: same gauge req'd on sq D double tap?

    I posed the question to see what opinions we would get in reply. Jim is correct and it generally is easier for me to look at double poles as two overcurrent devices with two poles and tandems as two overcurrent devices with a single pole.

    Looking at it this way as long as you do not increase spaces you cannot increase the number of circuit breakers allowed in the panel. So as long as I count circuit breakers and not number of wire terminations or count number circuit breaker poles I cannot get a circuit count that exceeds the max. number of circuits allowed by the manufacturer and UL ... assuming compliance with panel and circuit listings and labelings.

    If I start installing non-ctl breakers or sometimes called 'replacement only breakers' then of course circuits could be increased above the loadcenter labeling.

    **There isn't any load increase on the panel as the double tapped breaker terminal is a part of a single overcurrent device. Looking at it this way any amperage on one or combination of the two conductors exceed the single circuit breaker rating the breaker opens both conductors.

    Opening both conductors is a disadvantage only in that a perfectly good branch circuit may be down until you disconnect the bad one from the breaker and you are increasing the amount of possible load that the single circuit breaker protects vs a single termination.

    In other words if I had a heat gun operating on high (1800 watts) on a 20 amp QO double tapped single pole breaker I would be restricting the load on the other tapped conductor to 5 amps so load management becomes a bigger issue with Square d breakers in my opinion if you double tap them.


  14. #14
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    Default Re: same gauge req'd on sq D double tap?

    I am trying to figure out why some think there is a difference between having different size conductors when two conductors are used, when it is perfectly acceptable to have different size conductors when only one conductor is used ...

    Seems to me that the terminal plate would be at a GREATER angle with only one conductor than with different size conductors - and that would have been taken into the consideration for the design of the terminal plate (and it was according to Square D).



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  15. #15
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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Roger Frazee View Post
    I posed the question to see what opinions we would get in reply. Jim is correct and it generally is easier for me to look at double poles as two overcurrent devices with two poles and tandems as two overcurrent devices with a single pole.

    Looking at it this way as long as you do not increase spaces you cannot increase the number of circuit breakers allowed in the panel. So as long as I count circuit breakers and not number of wire terminations or count number circuit breaker poles I cannot get a circuit count that exceeds the max. number of circuits allowed by the manufacturer and UL ... assuming compliance with panel and circuit listings and labelings.

    If I start installing non-ctl breakers or sometimes called 'replacement only breakers' then of course circuits could be increased above the loadcenter labeling.

    **There isn't any load increase on the panel as the double tapped breaker terminal is a part of a single overcurrent device. Looking at it this way any amperage on one or combination of the two conductors exceed the single circuit breaker rating the breaker opens both conductors.

    Opening both conductors is a disadvantage only in that a perfectly good branch circuit may be down until you disconnect the bad one from the breaker and you are increasing the amount of possible load that the single circuit breaker protects vs a single termination.

    .
    Being that there are concerns of any type with double tapping breakers I am not understanding why any breaker manufacturer would say it is alright.

    As far as the discussion goes I remember less than a couple years back when everyone was questioning this including moist electricians.

    Funny how things change with acceptance over time.

    Even though a little smart assy looking at the different size wires as Jerry said it I would agree with there being no problem

    Not that I really wish to get that deep into it but I wonder what the make up difference is in breaker manufacture where it is OK to double one type and not another. I do think I read that somewhere already though.


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    Default Re: same gauge req'd on sq D double tap?

    Guess it all comes down to who wants to pay for what when it comes to getting things listed Ted.


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    Default Re: same gauge req'd on sq D double tap?

    <rant>
    For the life of me I don't see why so many folks take issues with two or more wires winding up terminated at one breaker - either "double tapped" on SQ-D or CH type CH, or two or more wires pigtailed to a breaker.

    Simply, if the breaker isn't tripping then it is not likely that it is overloaded. Again (and again) the case that can be made here is that you can run a home run for every receptacle. Later, if you need the panel space you can tie several of these home runs together and pigtail to a breaker. In the end, this is no different than if there was one home run to all the receptacles in the first place. The issue is the load on the circuit. And, in a residence you seldom know what the loads are going to be. There's a lot of stuff out there that will overload a circuit if anything else is added, and this can happen on a single duplex receptacle. And finally, you can put an infinite number of receptacles on most resi circuits according to the NEC.

    If you look at a side view of the contact plate on the breakers in question you will see that the plate doesn't tighten up on a single wire till it is tight against the other side (where the other wire would be if there was one) I'm not seeing how two wires different sizes is any different than a single wire in this type of termination.

    As an aside, most ground buss bars are approved for multiple wires and some for different sizes mixed. These are the "hole in the bar with a set screw" type connection. Multiple neutrals are not allowed on these because the possibility exists that someone loosening a neutral where several are under one termination might loosen a neutral for a multiwire circuit and burn something out as well as/or causing an intermittant connection on a circuit under load. The NEC makes the prohibition, UL has listed the bar for multiple wires. For those that don't know, although not significant in most cases, the ground (EGC) often carries current other than fault current. Many "lighted switches" and "smart devices" need a neutral connection to function correctly and lacking that connection in most switch boxes the manufacturers use the ground connection to get it.

    The house I worked on today is one where pigtailed circuits to a breaker were called out as a problem. I couldn't convince the guy that the total of 6 receptacles on one run and 4 receptacles on the other was the same thing as a single circuit with 10 receptacles on it. I only called him an idiot when I told him he'd missed the fact none of the receptacles in half the house were wired with cable that had a ground wire, and that the ground had been bootleged by running a jumper from the neutral to the ground terminal on each of the receptacles. He didn't see a problem with that as "both wires wind upon the same terminal in the panel anyway"

    Much bigger fish to fry than a breaker with multiple wires pigtailed to it.</rant>


  18. #18
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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Bill Kriegh View Post
    Many "lighted switches" and "smart devices" need a neutral connection to function correctly and lacking that connection in most switch boxes the manufacturers use the ground connection to get it.
    Most indicator/electronic/occupancy sensor switches do NOT use the ground to complete the circuit. Not to mention that if such a switch were installed on a circuit protected by a GFCI it would always fault.

    Instead most of those switches actually use the completed circuit to provide a current path. You will notice they stop functioning when the lamp is removed (provided there are no other lamps wired in parallel). As a result, use of these switches with CFL lamps typically causes problems.


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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Corn Walker View Post
    Most indicator/electronic/occupancy sensor switches do NOT use the ground to complete the circuit. Not to mention that if such a switch were installed on a circuit protected by a GFCI it would always fault.

    Instead most of those switches actually use the completed circuit to provide a current path. You will notice they stop functioning when the lamp is removed (provided there are no other lamps wired in parallel). As a result, use of these switches with CFL lamps typically causes problems.
    This improper use of the grounding conductor is supposedly driving the upcoming change requiring a neutral at each switch location in the 2011 code.


  20. #20
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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Corn Walker View Post
    Most indicator/electronic/occupancy sensor switches do NOT use the ground to complete the circuit. Not to mention that if such a switch were installed on a circuit protected by a GFCI it would always fault.

    Instead most of those switches actually use the completed circuit to provide a current path. You will notice they stop functioning when the lamp is removed (provided there are no other lamps wired in parallel). As a result, use of these switches with CFL lamps typically causes problems.
    Well, I've looked at the circuit diagrams for the devices in question or taken apart defective ones (this doesn't mean all devices) and they say otherwise. This is actually ONE of the reasons a neutral is being required at the switch boxes once the 2011 NEC is adopted........

    I also suspect this is one of several reasons the GFCI component of AFCI devices is being eliminated in new designs.

    Yes, I also know about the switches that really don't turn things all the way off. Just another of many sore points of compromised safety for convenience in the trade.


  21. #21
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    Default Re: same gauge req'd on sq D double tap?

    Quote Originally Posted by Bill Kriegh View Post
    Well, I've looked at the circuit diagrams for the devices in question or taken apart defective ones (this doesn't mean all devices) and they say otherwise. This is actually ONE of the reasons a neutral is being required at the switch boxes once the 2011 NEC is adopted........

    I also suspect this is one of several reasons the GFCI component of AFCI devices is being eliminated in new designs.

    Yes, I also know about the switches that really don't turn things all the way off. Just another of many sore points of compromised safety for convenience in the trade.
    That's why I said "most." I'm aware of a few devices that improperly use the grounding conductor as a current return path, and I wonder if there's been an increase in such devices with the popularity of CFLs. Most of the reputable device manufacturers do not use the grounding conductor but there are some that do.

    As for the safety of switches that use the completed circuit to power electronics or illumination, some have an air gap switch to disconnect power when servicing lamps. Of course I doubt many homeowners are aware of them, let alone know how to operate one.


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