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Thread: Pentair Variable Speed Swimming Pool Pump GFCI

  1. #1
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    Pentair Variable Speed Swimming Pool Pump GFCI

    Pentair has had problems with their variable speed pumps tripping GFCI's and recommends installing a GFCI with a higher mA threshold. As detailed below in UL 943C, this would be a Class C, D or E.

    Typically, I use Siemens QF220A or Pentair's PA220GF (Note: Originally, Pentair released incorrect information that the PA220GF had a higher threshold than 6 mA - it doesn't. They had UL issue a "Multiple Listing" on their breaker which means that the PA220GF is actually the Siemens QF220A with a Pentair label. I confirmed this with UL and Siemens).

    All circuits I'm working with are 120 or 240 VAC and have 12 gauge ground wires.

    After perusing the information listed below, I still have several questions. If you have answers, would you please include where you found the information in NEC, UL, etc.?
    1. Is the QF220A a Class A GFCI?
    2. Is it allowed to use a GFCI with a higher threshold in this application?
    3. If so, which Class would I use? I'm pretty sure it's Class C but am not sure


    680.21 (C) states
    GFCI protection is required for outlets supplying pool pump motors connected to single-phase, 120V through 240V branch circuits, whether by receptacle or by direct connection.

    NEC Article 100 defines a GFCI as:
    A device intended for theprotection of personnel that functions to de-energizea circuit or portion thereof within anestablished period of time when a current toground exceeds the values established for aClass A device.

    Following this definition, aFine Print Note provides additional informationon what constitutes a Class A GFCI device. Itstates that a Class A GFCI trips when the currentto ground has a value in the range of4 mA to 6 mA, and references UL943, the Standard for Safety for Ground-FaultCircuit-Interrupters.

    In 2009 UL published UL 943C that established three new classes of special purpose GFCI's intended for higher voltage:

    • Class C: for use in circuits with no conductor more than 300 V to ground (i.e., systems where line-to-line voltage is 480 V or less) where reliable equipment grounding or double insulation is provided.
    • Class D: for use in circuits with one or more conductors more than 300 V to ground (i.e., 600 V systems), and with specially sized, reliable grounding, to provide a low impedance path so that the voltage across the body during a fault does not exceed 150 V.
    • Class E: for systems similar to Class D, but with special high-speed tripping required that eliminates the need for the oversized ground of Class D.

    Class C, D, and E GFCI's trip at 20 mA rather than the 6 mA trip current mandated for Class A GFCI's. This increase in GFCI trip level is allowed by UL assuming the availability of a reliable ground in parallel with the body. During a fault, the grounding conductor will shunt the fault current around the body and cause the device to trip. This provides the let-go protection, while the 20 mA threshold provides protection against fibrillation. (If there is no grounding conductor, such as in two-wire household products, then the GFCI must provide both let-go and fibrillation protection, and a Class A device is required.)

  2. #2
    Join Date
    Dec 2010
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    Tennessee NEC:2008
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    Since there is already currently a thread with the same subject I think this will only lead to confusion.
    With that said, I'm closing this thread.
    Please see this thread for the answers or ask another question within the thread.
    http://forums.mikeholt.com/showthread.php?t=185253
    If you aim at nothing, you will hit it every time!

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