Grounding an above ground pool

35850 Views 18 Replies 7 Participants Last post by Speedy Petey, Sep 2, 2009

wcolon

Discussion Starter · Jun 23, 2009

What is the appropriate method (code compliant) for grounding an above ground pool pump? I've already bonded to the pool, but it seems there is much confusion on grounding.

Please help.

Thanks,
Will

1 - 19 of 19 Posts

Speedy Petey

· #2 · Jun 23, 2009

The pump is grounded with the insulated ground run with the circuit conductors.
There is a little green screw in the wiring compartment area.

Bonding is something else entirely.

wcolon

Discussion Starter · #3 · Jun 23, 2009

Thanks. A couple more facts I should have added.

The "proline" pump has a twist lock plug.

I wired this as follows:

I ran THWN #12 from inside my basement, with a 20 amp GFI breaker. One white, one black and one green.
Once outside the basement the THWN is run in sched 40 PVC conduit to a 20 amp switch. covered with a marine grade cover.
from the switch, I ran the wiring to the "twist lock receptacle", with an "in use" cover.
I opened up the motor housing and see the grounding screw.
I'm confused as to what to run from this grounding screw.
The grounding screw does have a green that runs from the screw up through the cord.

Again, don't know what to run from motor ground screw and to where.

Much appreciated.

Will

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J. V.

· #4 · Jun 23, 2009

The green that started in the basement panel will connect to the ground terminal on the motor. Did you run conduit from the basement panel to the outside. You said that you started with PVC once you got outside. THWN conductors must be in conduit and not exposed like a cable can.

Quote: "I'm confused as to what to run from this grounding screw". You run the green wire to the motor grounding screw. From panel to motor.

KeithM62948

· #5 · Jun 23, 2009

It seems to me that if the pump is grounded by the ground wire in the cord, and your twist-lock outlet is properly wired, you're good to go.

wcolon

Discussion Starter · #6 · Jun 23, 2009

Thanks. The THWN is in conduit (outside). The black, white, and green are run through the conduit to the switch. The green is attached to the grounding screw on the switch.

From the switch I've run the black, white, and green to the "twist lock" receptacle. I have the green attached to the grounding screw on the "twist lock" receptacle...... in the weatherproof receptacle box.

So...where to from here?

Many, many, thanks.

Will

J. V.

· #7 · Jun 24, 2009 (Edited)

wcolon said:
Thanks. The THWN is in conduit (outside). The black, white, and green are run through the conduit to the switch. The green is attached to the grounding screw on the switch.

And then the green continues to the receptacle.

From the switch I've run the black, white, and green to the "twist lock" receptacle. I have the green attached to the grounding screw on the "twist lock" receptacle...... in the weatherproof receptacle box.

So...where to from here?

Just like in the switch box the green continues on to the motor. The male end that plugs into the female twist lock recept has a green wire too. This green in the male plug cable is what goes to the ground screw in the motor. I hope this clears it up for you. You must not have the male plug and cord. If you did you would not have needed to ask this question, right?

Many, many, thanks.

Will

:wink:

KeithM62948

· #8 · Jun 24, 2009

JV, take another look at this. The way I read it, he has a properly grounded outlet & a pump that has a proper 3 wire cord & plug:

The grounding screw does have a green that runs from the screw up through the cord.

(and I'm presuming is properly attached to the plug)

It seems to me you're advising that he bypass the grounding prong of the plug in favor of hard-wiring the ground.

wcolon

Discussion Starter · #9 · Jun 24, 2009

Yes, you guys are correct. The cord from the pump has 3 wires, with a twist lock male plug. I guess, my confusion all along has been, do I need another separate green ground wire run to the pump.

Some electricians have told me yes, some no. I've also had electricians tell me I had to use a grounding rod, but from what I have read, that can be very dangerous.

My thinking all along was if the cord plug is a wired with the black white and ground, and the twist lock male is plugged into a properly grounded, twist lock receptacle, with a GFCI reaker at the panel, then I was ok and code compliant.

Thanks guys,
Will

KeithM62948

· #10 · Jun 24, 2009

My thinking all along was if the cord plug is a wired with the black white and ground, and the twist lock male is plugged into a properly grounded, twist lock receptacle, with a GFCI reaker at the panel, then I was ok and code compliant.

That's what I think, too, Will.

Stubbie

· #11 · Jun 24, 2009 (Edited)

2

You mentioned that your thwn is only in conduit outside......it must be in conduit the entire run from panel to receptacle. Maybe I misunderstood but that seems to be what you are saying.

The 'ground' your talking about is the equipment ground. It starts at the panel and continues to the motor.....end of story. It facilitates the current path for any fault to ground (metal) in the motor branch circuit. This is so enough current will flow to trip out the gfci breaker on any overcurrent fault.

The motor, if it isn't double insulated, will have a bonding lug. You connect to that lug with a #8 copper bonding wire. This wire then continues to all metal parts of the pool structure plus accessories like metal ladders and anything within 5 feet of the waters edge that is metal. This 'grid', bonding all metal, is the equipotential bonding grid and prevents changes of potential between the metal around your pool. This helps prevent shock hazards that are created from external sources This is probably the other ground that the electricians are telling you about. It just isn't a ground like the green in the motor branch circuit wiring. It doesn't ground anything it merely is a bonding wire joining all metal and metal equipment associated with the pool.

If the motor is double insulated then there will not be a bonding lug present, however you still must locate a #8 copper close to the motor to facilitate the replacement of the double insulated motor with one that is not double insulated.

So two things at the motor....the equipment ground of the cord and plug terminates (ends) on the motor wiring compartment green grounding screw. Nothing else continues on from that green screw. The #8 bonding wire is connected to the lug on the outside frame.......your done.

The attached image is for an inground pool but gives you the general idea for the joining of metal around and part of the pool. The second image is an above ground pool pump. These show what Speedy was distinguishing in post #2...bonding vs grounding.

Above ground pool pump (hardwired). The equipment ground is inside the flex weathertite conduit and terminates on the green screw inside the motor wiring compartment. Also the bonding wire is terminated to the bonding lug as shown.

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wirenut1110

· #12 · Jun 24, 2009

The ground is allowed to be uninsulated when in the interior of a dwelling (nm cable). Another FYI, the twist-lock plug is only required if the receptacle is between 5 and 10' of the pool. If it's 10 or more feet, it can be a regular plug.

wcolon

Discussion Starter · #13 · Jun 25, 2009

Thank You.

With regard to the below statement

"So two things at the motor....the equipment ground of the cord and plug terminates (ends) on the motor wiring compartment green grounding screw. Nothing else continues on from that green screw. The #8 bonding wire is connected to the lug on the outside frame.......your done."

Do you mean that the cord coming out of the motor (which has a green connected to the ground screw in the motor housing) with the twist lock plug, is essentially my "completed ground"....when it's plugged in to the twist lock receptacle?

Thanks again.
Will

Stubbie

· #14 · Jun 25, 2009

Thank You.

With regard to the below statement

"So two things at the motor....the equipment ground of the cord and plug terminates (ends) on the motor wiring compartment green grounding screw. Nothing else continues on from that green screw. The #8 bonding wire is connected to the lug on the outside frame.......your done."

Do you mean that the cord coming out of the motor (which has a green connected to the ground screw in the motor housing) with the twist lock plug, is essentially my "completed ground"....when it's plugged in to the twist lock receptacle?

Thanks again.

Yep, you got it but you may not understand it.....

Any fault to the metal of the motor case will cause the fault current to flow to the green screw then to the green wire of the twist-lock power cord, then to the receptacle then to the equipment ground of the motor branch circuit wiring back to the panel neutral bar then out to the transformer center tap over the service neutral. This low impedance path back to the source (transformer) allows enough current to flow through the gfci breaker during the fault to trip it out.

J. V.

· #15 · Jun 25, 2009

KeithM62948 said:
JV, take another look at this. The way I read it, he has a properly grounded outlet & a pump that has a proper 3 wire cord & plug:

The grounding screw does have a green that runs from the screw up through the cord.

(and I'm presuming is properly attached to the plug)

It seems to me you're advising that he bypass the grounding prong of the plug in favor of hard-wiring the ground.

No I'm not saying he should bypass the receptacle ground. Wired correctly, the twist lock plug and receptacle will have the ground present and no other ground connections are needed. (excluding the bonding system). What I tried to convey is if he has a metal box it needs grounding too. Thats why I suggested he pigtail the EGC and bond the metal box. If it's plastic he does not need to break the EGC. The twist lock plug and recept will deliver the EGC to the motor.

Aint it great to have Stubbie back!

wcolon

Discussion Starter · #16 · Jun 25, 2009

Thanks Stubbie. I understand.

One more question, what happens when the switch is off, but the plug is still plugged in to the receptacle.............am I still protected?

Once again, thank you.

Will

Stubbie

· #17 · Jun 25, 2009 (Edited)

The electrical branch circuit will be protected up to the switch... when it is off. If a fault occurs on the load side of the switch (motor side) as soon as you turn on the switch letting power to the motor the gfci breaker will instantly trip. Basically any current flow that is irregular to the gfci and what it expects to see on that motor branch will cause it to trip.

The gfci cannot 'see' a fault without current flow so power must be applied to the branch circuit. The gfci will react to any fault when power is being utilized or not utilized anywhere on the branch circuit if your using a gfci breaker. In other words if the switch is off and a fault is created for whatever reason at the motor or the wiring from the switch to the motor as soon as you turn that switch on the gfci is going to trip out. If a fault occurs during operation of the motor the gfci will trip. If a fault occurs between the switch and the gfci breaker with the switch off the gfci will trip.
Remember gfci breakers are combination devices the gfci part trips when very small leakages (5ma or so) of current go to ground or to a grounded leg (white wire) such as an insulation failure in the motor. They also will trip on overload or overcurrent just like any other breaker.

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derjuggernaut

· #18 · Sep 2, 2009

have an above ground pool. was asked to ground it or bond it. can i do this myself. pleasea advise. thanks.

Speedy Petey

· #19 · Sep 2, 2009

derjuggernaut said:
have an above ground pool. was asked to ground it or bond it. can i do this myself. pleasea advise. thanks.

No. Call an electrician familiar with pool bonding.

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