Swmming Pool bonding megger test

[sevlander]

We are being asked to test the existing bonding of a public pool. Is there a recommended procedure for this. We plan to connect a wire to the pump, stretch it out to each metal device (ladders, eyelets, etc) and record readings. In a preliminary run we had clean readings, but we also get near the same readings if we connect the megger leads directly into the earth. we don'yt trust these readings. Any suggestions?

 

[CONDUIT]

Don't know if this will help but look at attached link.

http://ewh.ieee.org/conf/tdc/IEEE_T&D_April_2008_Lambert.pdf

 

[sevlander]

Thanks for the link. Not sure that is what I need. Just looking for the proper method to confirm that the existing pool ladders and other metal are bonded properly. Not finding any kind of standard for this procedure.

 

[petersonra]

Thanks for the link. Not sure that is what I need. Just looking for the proper method to confirm that the existing pool ladders and other metal are bonded properly. Not finding any kind of standard for this procedure.

I am not sure there is one.

 

[don_resqcapt19]

You talked about using a megger. That is the generic term for an insulation testing meter. That would not be the correct tool for the job. You need a low ohms tester. If everything is correctly bonded, the readings should be very low...well less than one ohm.

 

[Fulthrotl]

We are being asked to test the existing bonding of a public pool. Is there a recommended procedure for this. We plan to connect a wire to the pump, stretch it out to each metal device (ladders, eyelets, etc) and record readings. In a preliminary run we had clean readings, but we also get near the same readings if we connect the megger leads directly into the earth. we don'yt trust these readings. Any suggestions?

here is what i did on a public pool.

it was a replaster job, and the city inspector wanted the *existing* wet niche shells REMOVED
from the side of the pool, so he could inspect the bonding. destroying them in the process.

the deck wasn't poured yet, so... i drove a ground rod in two places, did a cadwelded loop
all the way around the perimeter of the pool, then cadwelded the #6 tails from the five
existing wet niche shells to this wire, and finally, took a #6 over to the pool equipment area,
and bonded everything to it.

here is what i did that made the inspector go away happy:

the pool was full of water, so i taped a test probe to a stick of pvc plastic pipe,
clipped the other lead to the ground wire loop out in the dirt, and put 1,000 VDC
to the bezel of the light, and measured the voltage able to be maintained across
the ground.

as difference of potential is what is required for a shock hazard, i was measuring
if the pool water and ring had 1KV dropped on them, how much difference of potential
would there be between that, and the ground wire in the dirt. the fluke meter will
show the voltage between the test leads.

it showed 0.0 ohms, with 1 VDC between the test leads, so it would not be possible
for you to get shocked with 1KV in the water, grabbing a ground rod.

the inspector smiled, nodded, signed off on the final for the pool, and all was well.

 

[sevlander]

Procedure?

Procedure?

I actually contacted the author of the article in the link provided by "Conduit" He sent me a 90 page test results done at Georgia Tech. While very extensive, it was not testing for proper existing bonding. He did however tell me as "Don" did in his reply that a insulation tester (megger) is the wrong tool for the job and that a less the 1ohm resistance tester should be used.
My question then goes back to the proper method. I assume we would connect a wire at the main pump and string it to all metal component and take resistance readings.

Does anyone agree or does there need to be multiple ground points or rods driven in addition to test? What is an acceptable ohm reading for this test?

Some townships and insurance companies are asking for these tests, but do not have details of what they are actually asking for.

 

[don_resqcapt19]

....

Does anyone agree or does there need to be multiple ground points or rods driven in addition to test? What is an acceptable ohm reading for this test?

....

This is not a ground resistance test. Testing to remote electrodes is not of any value.

Your proposed method is the correct method as long as you use the the correct type of instrument.

As far as the ohm reading it should be very low. The bonding is to be via a #8 copper. The DC resistance of #8 copper is less than one ohm per 1000'. You would have the resistance of the wire, the connections and the metal part. I would expect to see readings of less than one ohm. When testing multiple points, you would also look for a reading that is out of line from the other readings.

 

[sevlander]

Thank you!

 

[RICK NAPIER]

I see you are from NJ and the UCC requires a bonding certificate every 5 years for swimming pools in other than one and two familiy dwellings. Unfortunately the Uniform Construction Code requires the certificate but does not provide any requirements so anything is acceptable. That being said for a proper bonding test you first need to disconnect the ground wires so as not to take your readings through the grounds and not the bond path. Second each bonded part should be tested to every other bonded part so as to ensure the minimum resistance between any two bonded parts. Since there is no code on the maximum allowed resistance you are taking the liability that the number you settle on will hold up in court should anything happen. The grounding system should be tested seperately. Here is the UCC requirement:

5:23-2.20

(e) The bonding and grounding certificate for swimming pools, spas and hot tubs, shall be issuedby a recognized electrical testing agency or a New Jersey State licensed electrical contractor.This certificate shall verify the continuity and integrity of the bonding and grounding system. It shallbe valid for five years from the date of issuance. The bonding and grounding certificate may cover more than one swimming pool, spa, and/or hot tub unit.
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[GoldDigger]

Second each bonded part should be tested to every other bonded part so as to ensure the minimum resistance between any two bonded parts. Since there is no code on the maximum allowed resistance you are taking the liability that the number you settle on will hold up in court should anything happen.

If you have 20 metal parts, your method would require 190 separate meter readings.
As an alternative, assuming that it passes, you could set an ohm value limit for point-to-point and then just make sure that the readings from each point to a single selected point are less than half that number. Mathematically, you get your result in only 19 measurements.
Disconnecting all of the grounds is still a pain!

 

[sevlander]

Thanks Rick...more good information. Gotta love how we have more and more well intended rules with no direction as to how to incorporate them. The powers at be make the requirement, but want no responsibility after that!

 

[don_resqcapt19]

Why would you need to disconnect the grounding conductors? Even if the bonding path is via an EGC, it is still a bonding path. The EGCs of any pool equipment are required to be connected to the bonding system.

 

[sevlander]

test procedure article.

test procedure article.

Here is a short article on test procedure from Megger corp. given to me by a supplier. It describes using an insulation tester and the New Jersey requirements. I could not attach it for some reason so I had to paste it in. Please read and reply.

Headline: Testing Swimming Pools Can Save Lives
Dallas, TX ? November 10, 2009 -- In Orange, Texas in 1991 a father drowned in a motel swimming pool after saving his three children who were screaming that they were being shocked. A second man, a cook at the motel, tried to save the father but he too was paralyzed by electricity and drowned.
The investigation determined that a wiring mistake had applied live current to a ground wire connected to the cover of one of the pool's underwater light. The children were far enough from the light that they received minor shocks. The two men swam close enough to the light to receive greater shocks and couldn't swim away.
There have been many such instances that brought into question electrical safety in and around public swimming pools. Then, in 1996 in New Jersey a life guard at an apartment complex was electrocuted by high voltage in the pool water.
Victor V. Timpanaro a member of the New Jersey Division of Consumer Affairs, State Board of Examiners of Electrical Contractors decided to formulate an ordinance for the testing and certification of existing community and public pools.
It was a two fold law. The first part provides an annual visual inspection of any pool wiring in the pool equipment room to determine whether any violations of the current electrical code is present which could contribute to a hazard to those using the pool.
Second, it requires a testing company to test all non-electric, metal parts of the pool and other metal appurtenances within 5 ft. of the pool in accordance with the NEC.
In 1998, the law was passed in New Jersey and compliance to the law is required before a pool can be opened for use or occupied by any person.
Testing is performed in two stages each requiring their own documentation:
Monday, May 13, 2013
Lou Iaconelli tests a ladder using the Megger MIT420
1/ An annual electrical inspection is conducted by a local inspector who issues an Electrical Certificate of Compliance.
2/ The Bonding and Grounding Certificate verifies the electrical continuity and integrity of the bonding and grounding system of the pool. It is issued by a recognized electrical testing agency or a licensed electrical contractor and is valid for five years. The Bonding and Grounding Certificate is a prerequisite for the Electrical Certificate of Compliance
If testing reveals any defective electrical condition on the pool premises, that condition must be repaired by an electrical contractor licensed in the State of New Jersey prior to issuance of the Electrical Certificate of Compliance
The Bond Test:
Megger?s MIT420 Insulation Resistance and Continuity Tester has been the instrument of choice of Lou Iaconelli. He has successfully performed tests at over 140 locations both commercially and residential pools in over 10 years and is a member of IAEI. Lou has also taught the National Electrical Code.
Iaconelli selected the MIT420 because it has memory recall and the necessary minimum output of 20mA. An excessive applied voltage would flash across any bad bond and indicate a failed bond was viable. A standard Digital Multimeter is unsuitable because you don?t get the output to offset the effects of any DC voltage present in the pool water. Earth Ground Resistance of 25  or less is not meant to be an acceptable value for this test as spelled out in the regulation. The acceptable level for most pools is .5  or less. It might be acceptable as high as 2  based on the geometry of the pool.
Continuity tests are preformed only on the equipment ground and not the grounding electrode system. Depending on the AC output, there may be problems if the voltage of a typical ground resistance tester is too high especially if the bonds are
Monday, May 13, 2013
Iaconelli and Art Todd check the reports generated by the Megger MIT420
oxidized or if there is a loose connection you could flash across a bond instead.
To perform the test, have on hand two rolls of #8 wire, one 175 ft and the other 250 ft. Which roll to use depends on the distance to longest test point. The Megger MIT420 is connected to each end of the roll of wire and its null feature is used to zero out the test lead resistance.
Determine the location of a good reference point to connect the test leads.
If there is underwater lighting, connect to a point at the underwater pool lighting deck box. The Equipment Grounding conductor should be disconnected and the negative lead for the Megger tester connected to it as a reference point. Connect the instrument?s other lead to a long pole with a probe at the end which makes contact with the bonding screw at each underwater light fixture.
For pools without underwater lighting, the referenced test point is the pump with a disconnected bonding conductor. Connect the MIT420 in the same way to this point and use the other test lead to make contact at various test points.
Test every non-electric, metallic bonding point on all amenities that are connected within 5 feet of the pool area. This will include drains, skimmers, gratings, ladders, slides, diving boards/stands, railings, fencing, handicap lift chairs and ramp railings.
The Ground Test:
Next, perform a ground test from the service panel to the circulation pumps frame, filter, heater, motor starters, junction boxes, switches and piping.
Evaluate and record what the resulting resistance is in accordance with IEEE standard of a maximum value of 1 between metallic surfaces which represents the maximum
Monday, May 13, 2013
value allowed. Generally, the results are less than .5 The Megger MIT420 will store the resistance at each test point and clearly identify each result. Recall the test results and the associated test number the instrument assigns. Transfer this data to the customer report.
The Voltage Gradient Test:
Tests for spurious voltages in the pool water are conducted using a Voltage Gradient Test Probe since damaged underwater fixtures or improperly wired branch circuits provide the highest potential for human exposure.
Conclusion:
While New Jersey has been enforcing this law since February 1999, it is our hope that more attention be given within other States.
The bonding and grounding instrumental testing of public swimming pools, spas and hot tubs may someday become a national concern. The State of New Jersey has taken the necessary steps by mandating it as an important matter of public safety.

 

[zog]

That was published by Megger????? The MIT420 is the wrong tool for both of those tests.

 

[RICK NAPIER]

If you have 20 metal parts, your method would require 190 separate meter readings.
As an alternative, assuming that it passes, you could set an ohm value limit for point-to-point and then just make sure that the readings from each point to a single selected point are less than half that number. Mathematically, you get your result in only 19 measurements.
Disconnecting all of the grounds is still a pain!

This does make better sense.

 

[sevlander]

supposedly

supposedly

The article had Megger logo on top and was supposedly given to the supplier from Megger. This is why I posted it. The answers on testing pools all seem to conflict depending on who you talk to. I am contacting Megger rep per the supplier's advice with a contact name he has given me. Supplier wants to sell a low resistance meter to test the pool believing it to be the correct method, but at same time showed me this article using MIT410 insulation tester!

 

[zog]

The article had Megger logo on top and was supposedly given to the supplier from Megger. This is why I posted it. The answers on testing pools all seem to conflict depending on who you talk to. I am contacting Megger rep per the supplier's advice with a contact name he has given me. Supplier wants to sell a low resistance meter to test the pool believing it to be the correct method, but at same time showed me this article using MIT410 insulation tester!

The correct tool for checking the bonded connections is a microhmeter (AKA: DLRO, Ductor, etc..). Checking the resistance to ground is a completely different test and has a few allowable test methods (And therefore different equipment) but the most commonly used is a 3 point fall of potential method.

I would assume the "supplier" is just a test equipment sales rep and is not actually from Megger.

 

[sevlander]

what is right then?

what is right then?

ZOG if they are both wrong...what is the correct tools and test?

 

[zog]

ZOG if they are both wrong...what is the correct tools and test?

Um, what I said in the last post.