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  1. #1
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    Default Double tap question

    Was viewing a service entrance today -- it had one double tap. But both of the wires were to the furnace. Should this be called out, or is that double tap allowed?

    Thanks.

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  2. #2
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    Default Re: Double tap question

    The only double taps allowed, that I'm aware of, are where the breakers are designed to hold more than one wire, such as some of the Square D breakers. It makes no difference what the wires are feeding.

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    Default Re: Double tap question

    Cool. that's what i figured, just didn't know if there was some weird exception if both wires were running to the same appliance.

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    Default Re: Double tap question

    The problems associated with double taps are due to the connections not being able to handle multiple wires.

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    Default Re: Double tap question

    Quote Originally Posted by Jon Errickson View Post
    Cool. that's what i figured, just didn't know if there was some weird exception if both wires were running to the same appliance.

    "both wires were running to the same appliance"

    That creates a new problem as you have described the installation. You are describing parallel conductors, however, parallel conductors are not allowed unless at least 1/0 in size ... and I doubt those conductors going to the furnace are at least 1/0 in size.

    Are you sure they go to the same appliance? If so, other factors also come into play when conductors are installed in parallel.

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  6. #6
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    Default Re: Double tap question

    Yes -- they run to the same romex wire that then runs through some conduit to a furnace, not far from the service panel. (the furnace wasn't functioning coincidentally -- the thermostat wasn't responding). And they were not 1/0 in size, they were 14AWG.

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  7. #7
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    Default Re: Double tap question

    Quote Originally Posted by Jerry Peck View Post
    "both wires were running to the same appliance"

    That creates a new problem as you have described the installation. You are describing parallel conductors, however, parallel conductors are not allowed unless at least 1/0 in size ... and I doubt those conductors going to the furnace are at least 1/0 in size.

    Are you sure they go to the same appliance? If so, other factors also come into play when conductors are installed in parallel.
    Unless , of course they are 2 circuits going to different items at the furnace. Say 1 circuit for the blower, and 1 for say a humidifer. Then it's just multiple conductors at one termination ( "double tap" as it's said here)


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    Default Re: Double tap question

    Quote Originally Posted by ken horak View Post
    Unless , of course they are 2 circuits going to different items at the furnace. Say 1 circuit for the blower, and 1 for say a humidifer. Then it's just multiple conductors at one termination ( "double tap" as it's said here)
    Right. Now the other question which Ken brought up - Was it a Square D breaker?


  9. #9
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    Default Re: Double tap question

    It was not a Square D breaker -- it was Siemens. I'll write it up as a double tap. Thanks.

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    Default Re: Double tap question

    Quote Originally Posted by ben jacks View Post
    Jon,
    Also note that a same circuit parallel phase conductor must be 1/0 Awg or larger for NEC 310.4 compliance. rbj
    Better figure out IF it is a parallel feed first.
    That is what I was getting at in my prior post. DO NOT just ASSUME it's a parallel feed, it could very well be 2 circuits. Better to be postive then report it incorrectly and look like your not knowledgeable in the subject!!


  11. #11
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    Default Re: Double tap question

    I wasn't assuming that. Either way, it's a double tap that isn't allowed (since it's not a Square D breaker). So whether or not it's a parallel circuit, the double tap is not allowed -- which is what i pointed out. Right?

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  12. #12
    Bert de Haan's Avatar
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    Default Re: Double tap question

    Quote Originally Posted by Jerry Peck View Post
    .... You are describing parallel conductors, however, parallel conductors are not allowed unless ....
    What are parallel conductors? Two conductor sharing a load so there are two smaller conductors instead of one large one maybe?
    Thanks


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    Default Re: Double tap question

    Quote Originally Posted by Bert de Haan View Post
    What are parallel conductors? Two conductor sharing a load so there are two smaller conductors instead of one large one maybe?
    Thanks
    I think the circuit in this pic is a parallel circuit, doubled wires on a 20 amp FP breaker, tsk, tsk.

    In Canada, #14 is allowed on 20 Amp heater circuit.

    I suspected the doubled wires both feed baseboard heaters but was leaving that part for the electrician, so "Repair ....double-tap ....blah blah."

    (Looking at the pic now, maybe they were #12 ga, but I called it out, and suspect the 40 Amp above is undersized.)

    (Yes before everybody chimes in, it is a Canadian Federal Pioneer Stab-Lok and we use them faithfully here in about 40% of the places I inspect, including my own. )
    (BTW, the new breakers click off just as good as any others, and the stabs seem to grip better than the old black ones)

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    Default Re: Double tap question

    Quote Originally Posted by ken horak View Post
    Unless , of course they are 2 circuits going to different items at the furnace. Say 1 circuit for the blower, and 1 for say a humidifer. Then it's just multiple conductors at one termination ( "double tap" as it's said here)
    Which is why I said:
    Quote Originally Posted by Jerry Peck View Post
    Are you sure they go to the same appliance? If so, other factors also come into play when conductors are installed in parallel.
    If one set goes to the furnace and one set goes to a humidifer, they do not go to the same appliance.

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    Default Re: Double tap question

    Quote Originally Posted by Bert de Haan View Post
    What are parallel conductors? Two conductor sharing a load so there are two smaller conductors instead of one large one maybe?
    Thanks
    Correct.

    Among many other things, each set of parallel conductors is to be sized to carry the load of whatever they go to.

    That way, if one set is lost (damaged, cut, loose connection, etc.) the remaining conductors are still able to carry the load placed on them.

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  16. #16
    Ryan Stouffer's Avatar
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    Default Re: Double tap question

    Jon, just make it simple on yourself and write it as a double tap.


  17. #17
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    Default Re: Double tap question

    And if two different items being supplied brings up if that's allowed. Motors/50% fixed in place equipment, normally the furnace blower being a continuous use and a motor (or other inductive load like a power supply) for fixed in place install usually requires a dedicated circuit. (rating x 125% cannot exceed 50% to share). Therefore, very doubtful on 14 AWG it could be shared with the main air handler blower for a furnace anyway and would probably mess with any safetys/interlock circuits if any if for an induced draft motor or similar.

    Last edited by H.G. Watson, Sr.; 01-09-2010 at 08:48 AM.

  18. #18
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    Default Re: Double tap question

    Quote Originally Posted by Jon Errickson View Post
    Was viewing a service entrance today -- it had one double tap. But both of the wires were to the furnace. Should this be called out, or is that double tap allowed?

    Thanks.
    Quote Originally Posted by Jon Errickson View Post
    Cool. that's what i figured, just didn't know if there was some weird exception if both wires were running to the same appliance.
    Quote Originally Posted by Jon Errickson View Post
    Yes -- they run to the same romex wire that then runs through some conduit to a furnace, not far from the service panel. (the furnace wasn't functioning coincidentally -- the thermostat wasn't responding). And they were not 1/0 in size, they were 14AWG.
    Quote Originally Posted by Jon Errickson View Post
    It was not a Square D breaker -- it was Siemens. I'll write it up as a double tap. Thanks.
    Quote Originally Posted by Jon Errickson View Post
    I wasn't assuming that. Either way, it's a double tap that isn't allowed (since it's not a Square D breaker). So whether or not it's a parallel circuit, the double tap is not allowed -- which is what i pointed out. Right?
    Have to admit, I've had some difficulty with the description language, as when first appeared and before additional information was posted, my first thought was that the double tap was at the main lugs and possibly feeding a second buss/panel for an electric furnace. Decided to wait and see, glad I did on that first part .

    I'm still confused/wondering though, only two conductors (wires) mentioned and romex mentioned and 14AWG, if the double tap in question actually is a double hot tap landing on a breaker in the panel.

    I'm not trying to be picky, its just that the breaker brand response to question raised by JK, and the series of posts still didn't seem clear to me that the double tap location was actually two hots on a circuit breaker, and that the double tap was indeed HOT (ungrounded) taps; the mention of seimens breakers makes me wonder if this is seimens service equipment, if the double tap is neutral (grounded) conductors ("wires") or a neutral & ground sharing a tap. The former is allowed in some panels by virture of the listing and labeling to share the same terminal. A splice "tap" in in the panel for a MWBC neutral is also allowed.

    I'm still curious, two hots and two neutrals, two hots one neutral conductor? ground? in this "romex" feeding the furnace and humidifier or whatever? IOW how many conductors in this single romex cable and where did each of them land in the panel (or did the "both wires" mean two cables, each containing unknown number of conductors or "wires")? I am also still unsure if this "double tap" is ON a CB or for example two neutrals in the same terminal connection on the bar or a neutral and a ground sharing the same terminal. Some panels are listed, labeled and permit two neutrals (or even three 14AWG if same conductor material) to share the same terminal. Multiwire cable (such as "romex" and if so how many conductors, etc.), multiple cables, or multiple wires still unclear and haven't developed a sense of your own communication style so wondering.

    Without a picture and the way the discussion went, I'm still unclear what you saw and are asking about specifically, Jon Errickson, and I really want to make sure you do get the best/right information: would you mind please clarifying/enlightening (okay and indulging) me please, exactly what/which conductors are landing on what/where in the panel and where this "double tap" is (just want to be sure)?


  19. #19
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    Default Re: Double tap question

    HG -- you sound like me college english teacher -- always telling me to add more description

    I noticed the double tap when i was inspecting main circuit panel (i'm supposed to call that the service entrance, right? )

    Everything else in the box looked good. When i followed the two conductors in question they led back to the same NM wire, from which was also a ground and neutral that were properly terminated. That NM wire left the SE through metal conduit, over to one of the two furnaces in the basement (it was about 5 feet from the SE so i was able to follow it the whole way). That furnace did not respond to normal operating controls, so i never witnessed it operating.

    I know that Square D has the only kind of breaker that is designed for double taps, and i knew this wasn't one of them. I just didn't know if there was some odd exception when the two conductors in the double tap headed to a furnace.

    Sorry for any confusion -- it was the end of the day (my birthday in fact) and i was looking for a quick response so i could get on with my evening. I will work really hard to add more description next time.

    Thanks!

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  20. #20
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    Default Re: Double tap question

    I have never seen a NM cable with a red and yellow conductor along with the white and the ground that was said to be properly terminated. Something seems strange here.

    Also Square D is not the only brand that is UL listed for use with multiple conductors.


  21. #21
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    Default Re: Double tap question

    Maybe i'm remembering it wrong. I wish i could go back and have another look now.

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  22. #22

    Default Re: Double tap question

    I don't see that it matters where the wires are going to. The fact that there are two wires on the same breaker terminal it should be called up as a double tap.
    Manzoor


  23. #23
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    Default Re: Double tap question

    Quote Originally Posted by Jon Errickson View Post
    Maybe i'm remembering it wrong. I wish i could go back and have another look now.
    a picture is worth a thousand words or multiple trips back


  24. #24
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    Default Re: Double tap question

    Quote Originally Posted by Manzoor Husain View Post
    I don't see that it matters where the wires are going to. The fact that there are two wires on the same breaker terminal it should be called up as a double tap.
    Manzoor
    It should be reported for what it is!

    It could be 1 issue that is wrong or 2 issues that are wrong. Thats the difference.
    Multiple conductors on a circuit breaker is wrong
    Paralleling #14 is even more wrong

    By not writing up the proper incorrect issues one could possibly create an even more dangerous situation when attempting to correct what was reported !

    Think of it this way - you take your car to the shop because the front tires are worn unevenly. The mechanic just writes up a repair order to: Just replace the front tires with new ones.

    Is this the correct way to deal with this issue ? NO !
    One needs to also find out what else is wrong, that would lead to this situation. Could be misalignment,bad balljoints, improper air pressure.


  25. #25
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    Default Re: Double tap question

    Quote Originally Posted by ken horak View Post
    Multiple conductors on a circuit breaker is wrong
    MIGHT be wrong ... some breakers allow two conductors in their terminals. Square D has some rated for two conductors, and I think Cutler Hammer has some rated that way if I recall correctly.

    Which means that nothing might be wrong - unlikely, but a possibility which needs to be considered.

    If one is not sure if a breaker is allowed to be multiple tapped, then instead of writing it up as "multiple tapped and needs correction", write it up as "multiple tapped, verify number of conductors allowed in terminal and correct as as needed".

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  26. #26
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    Default Re: Double tap question

    I was responding to this thread
    Not a generalized statement.
    In reference to this thread my statement is correct.
    Multiple conductors on a circuit breaker is wrong.

    Original poster attached a photo showing the breaker as a siemens that is not set up for mutiple conductors


  27. #27
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    Default Re: Double tap question

    Quote Originally Posted by ken horak View Post
    I was responding to this thread
    Not a generalized statement.
    In reference to this thread my statement is correct.
    Multiple conductors on a circuit breaker is wrong.

    Original poster attached a photo showing the breaker as a siemens that is not set up for mutiple conductors
    Understood and correct, yes.

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  28. #28
    Bill Guthrie's Avatar
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    Default Re: Double tap question

    Quote Originally Posted by Jerry Peck View Post
    Correct.

    Among many other things, each set of parallel conductors is to be sized to carry the load of whatever they go to.

    That way, if one set is lost (damaged, cut, loose connection, etc.) the remaining conductors are still able to carry the load placed on them.
    Jerry-
    Each set of parallel conductors does not need to be sized to carry the full load. The equipment grounding conductor in each set DOES need to be sized according to the overcurrent protection but the individual "hot" wires do not need to be able to carry the full load. There are certain requirements but that is not one of them


  29. #29
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    Default Re: Double tap question

    I see bell transformers and panel outlets double tapped on EVERY panel I inspect.

    Why is it that all our electrical inspectors (in the state - not just town) allow this?

    I do write it up, but I see it so...oo often that I wonder if it is allowed??

    Any thoughts?


  30. #30
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    Default Re: Double tap question

    Quote Originally Posted by Bill Guthrie View Post
    Jerry-
    Each set of parallel conductors does not need to be sized to carry the full load. The equipment grounding conductor in each set DOES need to be sized according to the overcurrent protection but the individual "hot" wires do not need to be able to carry the full load. There are certain requirements but that is not one of them
    Bill,

    You are correct, I was thinking of the requirements for one of the exceptions to the 1/0 minimum size we had recently, which has that as one of the requirements.

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