Swmming Pool bonding megger test

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Am I reading this correctly from the procedure posted above, "The Equipment Grounding conductor should be disconnected and the negative lead for the Megger tester connected to it as a reference point." How does using a disconnected EGC as a reference help check the integrity of the EPB?
 
mark32 said:
Am I reading this correctly from the procedure posted above, "The Equipment Grounding conductor should be disconnected and the negative lead for the Megger tester connected to it as a reference point." How does using a disconnected EGC as a reference help check the integrity of the EPB?
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Giving them the benefit of the doubt, I read that as removing the EGC and connecting the reference wire where the EGC had been connected.
But don't forget to put it back when you are done. There are a couple of possible referents for the "it" in that sentence. I take it as the deck box itself.
 
zog said:
That was published by Megger????? The MIT420 is the wrong tool for both of those tests.
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It may be the wrong tool, but it is better than the average multimeter. It has a low ohms (precise to .01ohm) function which sends up to 200ma through the test leads and allows an *almost* convenient zeroing out of the lead resistance.
Certainly better for bond checking than the megohmmeter/HV test function of the same instrument.

With the ability to go up to 200A (!) the MOM2 microohmmeter is overkill for bond checking, IHHO.
 
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GoldDigger said:
It may be the wrong tool, but it is better than the average multimeter. It has a low ohms (precise to .01ohm) function which sends up to 200ma through the test leads and allows an *almost* convenient zeroing out of the lead resistance.
Certainly better for bond checking than the megohmmeter/HV test function of the same instrument.

With the ability to go up to 200A (!) the MOM2 microohmmeter is overkill for bond checking, IHHO.
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I agree a 200A microhmeter is overkill for this application but a 10A model is what should be used. Typically your connections will read in the microhm to milliohm range. And a micohmeter will negate the resistance of the leads.
 
Megger agrees

Megger agrees

I pasted on concerns from the forum responses to Megger. Megger responded to comments regarding the test article I posted earlier. The MIT 400 series has the ability to do the test as written in the article. The the setting used is micro ohms and the output is 20milli-amps. It is not used as an insulation tester in the article.
The 420 or 430 models are better in that they also data log the
readings for recording as you go and the capability to null the leads out of the resistance measurements for truer readings.
 
zog said:
That was published by Megger????? The MIT420 is the wrong tool for both of those tests.
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I had the MIT420 for several years before it got stollen and was great for insulation test. But for pool testing that I have been hire to investigate stray currents, I own a Fluke 1625 Earth Ground Testers. I connect one probe to the running motor bonding lug and the other end to the fence, ladders, niche lights (using pole). We test for voltage (AC/DC) and resistance. Once the ladder is confirmed to be grounded, we inject a trace current into it and see if we can trace the grid going around the pool (You have to careful as you might just be seeing the mesh). Many times we will also connect to the fence or ladder and confirm the same resistance to the other items just to make sure we didn't get fooled into thinking we had solid grounds.
 
Glennsparky said:
This is from the Megger article. It's is a misprint, right? It should say ground shouldn't it?
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Think about whether this particular connection is a grounding connection (to earth) or just a bonding connection (forming an equipotential grid that need not necessarily be at ground (earth) potential.)
 
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