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Thread: Pentair Variable Speed Swimming Pool Pump GFCI

  1. #1
    Join Date
    Sep 2017
    Santa Cruz, CA

    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
    Tennessee NEC:2008
    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.
    If you aim at nothing, you will hit it every time!

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