Is it necessary to ground the steel structure of an above ground pool?

Posted by on . 3 comments.


We recently had the pump on our pool replaced. It is an 1.5 HP Hayward PowerFlo LX pump. According to the manual, the motor should be grounded to a ground strap. However, it also states the following:



Bond motor to pool structure. Use a solid copper conductor, size or larger. Run wire from external bonding lug to reinforcing rod or mesh. Connect a No. 8 AWG (8.4 mm²) solid copper bonding wire to the pressure wire connector provided on the motor housing and to all metal parts of swimming pool, spa, or hot tub, and to all electrical equipment, metal piping or conduit within 5 ft. (1.5 m) of inside walls of swimming pool, spa, or hot tub. (In Canada use No. 6 AWG
bonding wire.)

We understand the need to ground the pump motor. However, we have never heard of the need to ground the metal parts of the swimming pool itself. The motor and the pool are connected with plastic hoses. What is the reason to ground the pool structure?

In addition, can anyone tell me how many amps a 1.5 HP pump motor would pull?

Comments

  1. Violet W says:
    August 4, 2009 at 3:52 pm

    Article 680 of the National Electrical Code states the requirements for swimming pools. It’s quite elaborate, so let me give a summary and paraphrase in the process. I base this on the 2002 NEC. There is a newer version in effect.

    In the definitions section (680.2), it defines permanently-installed pools and storable pools. Any pool that is in-ground, partially in-ground, or can hold water more than 42 inches deep without spilling is considered to be permanently-installed pool, as is any indoor pool regardless of water depth. Outdoor pools that are above ground and aren’t deeper than 42 inch water depth, or have completely non-metallic walls, are considered to be storable pools. Caveat: Your local Authority Having Jusidiction (AHJ) may have a different interpretation.

    The NEC makes a distinction between grounding and bonding.

    In either type of pool, electrical equipment has to have an electrical grounding conductor (a.k.a. be grounded).

    Permanently-installed pools have to have bonded together all (fixed) metal parts in the pool or outside the pool within 5 feet horizontally or overhead within various heights. This includes any metal structure, and the rebar or mesh in the pool walls (except for epoxy-coated rebar). There are a few limited exceptions.

    Storable pools don’t have the bonding requirement, but all electrical circuits have to be GFCI protected. They do have the grounding requirement, so your pump has to be grounded.

    What the code doesn’t say is this. Usually above-ground pools have portable filter pumps that are connected via flexible hose and via a power cord. The GFCI requirement and lack of bonding requirement make sense from the standpoint that budget-conscious above-ground pool owners are more likely to provide this level of protection than they are to go the bonding route. Permanent pools usually have buried piping and permanent electrical circuits that often are more extensive, so the opportunities for electrical shock increase, hence the bonding requirement.

    And as an aside, long runs of wiring will tend to nuisance-trip a GFCI breaker, especially with underground circuits that are constantly in a wet environment. So applying GFCI protection can be more difficult in permanent installations.

    The Hayward instructions appear to assume a permanent pool installation.

    In your case, decide which type of installation you have and go from there. It doesn’t hurt to have both bonding and GFCI protection. But it would be a mistake to have neither.

    =====

    Regarding motor amps, the NEC Article 430 requires usage of the following values for design purposes, for a typical 1.5HP single phase motor (Table 430.148):
    115V: 20A
    230V: 10A
    200V: 11.5A
    If you operate the motor on 208V single phase, use the 200V value (11.5A).

    In terms of actual amps drawn, the value will be somewhat lower as the NEC values have an allowance to cover things such as tolerances, control circuit current, and inefficient motors.

    I looked at the nameplate of a 1.5 HP Hayward PowerFlo LX pump. It stated 12.0A at 115V single phase. 12A is significantly less than 20A. The 20A governs for circuit calulcations, but the lower number is more appropriate for energy calculations.

    That said, the actual amps drawn can be even less if the mechanical load on the motor presented by the pump is less than 1.5 HP.

  2. fenx says:
    August 4, 2009 at 3:52 pm

    Public and commercial (resort) swimming pools are required by law, and the National Electric Code, to have any metal surfaces in and around the pool grounded to a common source. This is to prevent the case of severe shock to the public or private individuals.
    A 1.5 HP Motor with a 230 volt source will have approximately 5 amps of required current (amps).
    Equation I = P/E P is in watts, E is the voltage, I is the current. One HP = 746 watts.
    There is a lot written on this subject and check your local electrical code for further information.

  3. Buttsoap says:
    August 4, 2009 at 3:52 pm

    Sounds like you have a gunite pool pump meant to be bonded to the reinforcing bar in the pool structure.

    You ask a really good question that only an electrician can answer. But I consider your new pump to be a hazard until it can be installed properly.

    If you are using a 1.5 hp pump all you are doing is wasting money your pool will circulate quite nicely with a 3/4 hp pump.

    You’re welcome!!

Leave a Reply