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  1. #1
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    Default Double Pole 120 volt

    Assuming everything else is fine, if you are only using one side of an HACR type breaker, would the over current protection still be provided. For example, today had a 120 volt heater connected to one leg of a 220 volt HACR breaker. I was thinking the OCP would be the same as if it were on a single pole 20 amp breaker, but I'm not sure.

    I'm not asking if it's a code violation, just if the over current would work. I told the client to replace with a single pole breaker. The whole system was an epic mess, this was the least of it.

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    Jim Robinson
    New Mexico, USA

  2. #2
    Roger Frazee's Avatar
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    Default Re: Double Pole 120 volt

    Quote Originally Posted by Jim Robinson View Post
    Assuming everything else is fine, if you are only using one side of an HACR type breaker, would the over current protection still be provided. For example, today had a 120 volt heater connected to one leg of a 220 volt HACR breaker. I was thinking the OCP would be the same as if it were on a single pole 20 amp breaker, but I'm not sure.

    I'm not asking if it's a code violation, just if the over current would work. I told the client to replace with a single pole breaker. The whole system was an epic mess, this was the least of it.
    Yes the ocpd would work just fine but would take out the circuit connected to the other pole as it will either be handle tied or common trip. However it is possible for a handle tie to not cause the other tied breaker to trip

    Rather than me try to write a book this answer to a similar question in ECM Magazine does a good job ...

    Misunderstanding No. 4: Handle ties provide the same operation as internal common trip.
    Handle ties provide an acceptable method of linking operating handles of several single-pole circuit breakers together so they'll switch the tied circuit breakers together. Although good reasons exist for using handle ties, such as in multiwire branch circuits, the method in which a handle tie functions is often not well understood. And in some cases, application of handle ties may lead to unnecessary hazards.
    It's important to understand the difference between the handle tie feature and the common trip feature. Handle ties fasten the handles of two or more single-pole circuit breakers together. With handle ties installed, all of the poles are switched on and off together. However, if one pole trips because of an overload or short circuit, the handle tie doesn't cause the connected poles to trip. The condition can leave one pole tripped and the other tied poles energized.
    Multipole circuit breakers with common trip will switch all poles on and off together. They'll also trip all poles simultaneously when an overload or short circuit occurs on any of the poles. In this case, all poles operate together regardless of whether the circuit breaker is switched manually or opens automatically because of overcurrent.
    It's often impossible to determine the difference between the common trip 2-pole circuit breaker and two single-pole circuit breakers with handle ties unless you're familiar with the product design. The potential hazard arises when one pole trips and another pole remains energized. It's especially hazardous if someone assumes that all poles are tripped and open when only one pole is open.
    Consider a multiwire branch circuit as described in 210.4. Handle ties are frequently used in multiwire circuits. These circuits supply only line-to-neutral loads unless they supply only one piece of equipment or unless the overcurrent device opens all conductors simultaneously (common trip). By the definition in Art. 100, multiwire branch circuits have a grounded conductor with equal voltage between it and each ungrounded conductor. When one pole trips due to overcurrent, the remaining pole(s) is connected in a closed circuit with the grounded circuit conductor.
    Alternatively, consider a straight 240V circuit with no grounded circuit conductor. When one pole trips, the remaining pole(s) is energized with no return path through a circuit conductor. The pole will continue to serve the fault unless tripped or opened manually.
    The fundamental requirement of 240.20(B) is that the circuit breaker shall open all ungrounded conductors of the circuit. In other words, it calls for common trip. The section provides the following exceptions to allow the use of single-pole circuit breakers with handle ties:
    • In multiwire branch circuits
    • On circuits with line-to-line connected loads of grounded single-phase systems and on 3-wire DC circuits
    • With line-to-line loads in 3-phase, 4-wire systems and 2-phase, 5-wire systems
    In light of the fact that handle ties don't provide for common trip and the fact that the fundamental requirement is for common trip, it seems most reasonable to apply only circuit breakers with common trip in the second and third items above, where line-to-line loads are served. That means eliminating those two items as exceptions.
    The National Electrical Manufacturers Association (NEMA) has proposed eliminating these two items from the NEC, and the Code Making Panel is considering it. Acceptance of that proposal will require the installation of common trip circuit breakers in circuits serving line-to-line loads and require that all poles clear the circuit simultaneously.
    The requirements of 240.20(B) relate only to circuit breakers. They don't affect fuse applications. The separate disconnect for fuses is quite different from the integrated functions of a circuit breaker. Many users believe all poles of a circuit breaker open when one pole opens, without fully understanding the function of handle ties. Common-trip circuit breakers are readily available and are the standard for 2- and 3-pole circuit breakers.
    Handle ties have an appropriate place in providing a means for protecting multiwire branch circuits. However, they aren't a replacement for common trip and shouldn't be perceived that way.


  3. #3
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    Default Re: Double Pole 120 volt

    No problem.

    There are two basic types of double pole breakers: 1) two separate breakers installed with handle ties; 2) two separate breakers mounted together as one unit from the factory with an internal trip (think of it as a handle tie inside the breaker).

    Either way, you have basically two separate breakers tied together so that is one side trips the other side trips.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  4. #4
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    Default Re: Double Pole 120 volt

    Quote Originally Posted by Jerry Peck View Post
    No problem.


    Either way, you have basically two separate breakers tied together so that is one side trips the other side trips.
    Not quite.

    Internal common trip will trip both poles if only one leg is faulted or overloaded.

    Handle ties are designed so that an overload or fault will move only the handle for the pole that is overloaded

    Both arrangements turn off both poles when the breakers(s) are manually operated.

    The handle ties allow the overloaded leg on a multiwire circuit to trip and the other leg to continue functioning. At the point the tied breakers are reset both circuits will be off briefly as the circuit with no problems will be turned off as the tripped handle on the other breaker is moved to off. This meets the code requirement for a single disconnect on a multiwire circuit.

    The NEC doesn't prohibit 240 volt loads from being supplied from handle tied individual breakers. They aren't a good idea though as a faulted circuit will supply a ground connection for the pole that doesn't trip, esentially providing half voltage to the load.

    Each arrangement has it's place.


  5. #5
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    Default Re: Double Pole 120 volt

    For my own education, is the HACR type breaker by definition a double pole breaker that does not have a handle tie? Or is there more to the HACR designation than that? I thought it was, but seeing the comments about handle ties now I am not so sure. This did not have a handle tie, just one handle but a double pole breaker.

    Jim Robinson
    New Mexico, USA

  6. #6
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    Default Re: Double Pole 120 volt

    A HACR breaker is one that has settings that are able to withstand the hard starts of blowers and compressers in certain types of equipment. There is no rule that limits this type of breaker to this particular application, however. (all CH type breakers are HACR rated, for example) Since this equipment is found in many configurations you will see HACR on 1, 2, and 3 pole breakers.

    2 pole breakers are manufactured in several types. Some are a double wide breaker with a single handle (SqD comes to mind here). Some look like 2 single pole breakers with a handle tie. Careful attention to the labeling on the front is required to see if you have handle tied single pole breakers or a common internal trip variety.

    GE makes two types of 2 pole breakers. One looks like two standard breakers with a handle tie, the other like two half wide breakers with a handle tie.


  7. #7
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    Feb 2009
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    Default Re: Double Pole 120 volt

    Quote Originally Posted by Bill Kriegh View Post
    Not quite.

    Internal common trip will trip both poles if only one leg is faulted or overloaded.

    Handle ties are designed so that an overload or fault will move only the handle for the pole that is overloaded

    Both arrangements turn off both poles when the breakers(s) are manually operated.

    The handle ties allow the overloaded leg on a multiwire circuit to trip and the other leg to continue functioning. At the point the tied breakers are reset both circuits will be off briefly as the circuit with no problems will be turned off as the tripped handle on the other breaker is moved to off. This meets the code requirement for a single disconnect on a multiwire circuit.

    The NEC doesn't prohibit 240 volt loads from being supplied from handle tied individual breakers. They aren't a good idea though as a faulted circuit will supply a ground connection for the pole that doesn't trip, essentially providing half voltage to the load.

    Each arrangement has it's place.
    Thank you, Bill. In Canada, many kitchen outlets are supplied by split 15 amp receptacles, two hot wires to each outlet. (The new rules allow single 20 amp circuits). The code AFAIK, does not prohibit handle-tied double breakers for these 15 amp feeders. I sometimes find receptacles where only one of the two receptacles has lost power, due to only one side of the double breaker tripping in the panel. That will be a breaker with a handle tie.

    HI's in Canada need to test top and bottom of every kitchen outlet for this reason. Homeowners will assume the receptacle is half bad and simply stop using it. On the other end of the counter, they'll have another one that's also half bad.
    Usually, resetting the breaker clears the fault.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

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