How To Test Pool/Marina Grounding and Bonding Grid

[Sahib]

here is what i have done in the past to verify bonding on swimming pools. specifically wet niches.

1. shut off all power to pool.
2. take a fluke megger, i used the 1587, as it gives applied working voltage to the circuit under test.
3. tape one lead to a piece of pvc conduit.
4. attach the other lead to the pool ground.
5. stick lead on pvc pipe into pool, touching lead to pool light bezel.
megger @ 1000 volts between bezel on pool light, and earth ground.
6. you should read 0.0 megohms, as it should be a dead short.
7. however, your megger should also tell you how many volts it is maintaining
across the test circuit, and it'll be somewhere between 1 and 1,050 or so,
depending on the specific fluke you are testing with.
8. you should only see 1 or 2 volts displayed.

summary:
with 1000 volts applied to the pool, there is a difference of potential of only
one or two volts between the pool water, and the earth. this means the pool
light is correctly bonded.

it also means that a person perfectly grounded, sticking their hand in the pool
water when it became energized with 1,000 volts, might be subject to a 1 or 2
volt shock.

over the years, i've had three AHJ's agree with this assessment of correct bonding
of a wet niche fixture.

With only 1 or 2v across pool and ground with 1000V applied, the balance voltage must be dropped within your meter and so you are effectively applying 1 or 2 volts only.

 

[Sahib]

a person perfectly grounded, sticking their hand in the pool
water when it became energized with 1,000 volts, might be subject to a 1 or 2
volt shock.

over the years, i've had three AHJ's agree with this assessment of correct bonding
of a wet niche fixture.

It depends on internal impedance of source of 1000v. Suppose it has very small value and equal to pool to ground impedance value. Then 500v would be dropped internally in source impedance and balance 500v would appear in pool to ground path with dangerous consequences.

 

[don_resqcapt19]

... Also if pump motor doubly insulated, it should not be bonded. Should it?

Take a look at the last sentence in 680.26(B)(6)(a).

 

[Sahib]

Take a look at the last sentence in 680.26(B)(6)(a).

Take a look at 680.31. The inaccessible metal parts of the doubly insulated pump, though required to be grounded, should not be bonded. Should it?

 

[kwired]

Take a look at 680.31. The inaccessible metal parts of the doubly insulated pump, though required to be grounded, should not be bonded. Should it?

That section is in the storable pools, spas, hot tubs section and is a different breed from permanently installed pools and spas.