# Meggering switchgear/large panelboards



## jza (Oct 31, 2009)

Just don't megger with more voltage than the breaker can handle.


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## electricalperson (Jan 11, 2008)

so do you actually remove the breaker from the panel? thats how i would do it if i had to megger something like that.


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## Big John (May 23, 2010)

Yeah, rack out the breakers, pull the PTs, open the TVSS. You need to isolate everything. 

Even assuming this stuff is designed to withstand megger voltage (bad assumption) you still stand a good chance of getting an artificially low insulation reading because you're reading through some piece of equipment.

-John


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## Zog (Apr 15, 2009)

It depends on the equipment, you need to know when to do what. Just today I got a pile of breakers in that one of the big OEM service companies had failed 8/10 breakers due to bad trip units (High end expensive ones with ZSI and comms), found out why pretty quick, they did not pull the transducer isolation plugs and when meggering and fried $40,000 worth of trip units. :laughing:


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## piperunner (Aug 22, 2009)

*megging gear*

As John said and a few more things shut off or pull the control fuses out .
Remove bonding jumper for test .


Read your spec,s on your switch gear example SQ-D only needs 25 meg ohms on buss to pass you dont need much its open air bars so its low readings .

GE says on mostly new stuff we install today 100 meg ohms and you fine .

But read your own spec it may be different .

We megg at what the factory says voltage wise .


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## electricalperson (Jan 11, 2008)

Zog said:


> It depends on the equipment, you need to know when to do what. Just today I got a pile of breakers in that one of the big OEM service companies had failed 8/10 breakers due to bad trip units (High end expensive ones with ZSI and comms), found out why pretty quick, they did not pull the transducer isolation plugs and when meggering and fried $40,000 worth of trip units. :laughing:


whats a transducer isolation plug?


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## Zog (Apr 15, 2009)

electricalperson said:


> whats a transducer isolation plug?


My point exactly

Higher end trip units that use voltage and current inputs have transducers (Small PT's) to provide the voltage input to the trip unit and comm system, if you do not pull the isolation plug to remove them from the circuit you will fry the trip unit when you megger.


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## brian john (Mar 11, 2007)

Zog said:


> My point exactly
> 
> Higher end trip units that use voltage and current inputs have transducers (Small PT's) to provide the voltage input to the trip unit and comm system, if you do not pull the isolation plug to remove them from the circuit you will fry the trip unit when you megger.


 
But think of the sales it generates and the boost to the economy. QUIT BEING SO NEGITIVE.:blink:


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## Zog (Apr 15, 2009)

brian john said:


> But think of the sales it generates and the boost to the economy. QUIT BEING SO NEGITIVE.:blink:


Right, keep up the good work everyone!


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## electricalperson (Jan 11, 2008)

Zog said:


> My point exactly
> 
> Higher end trip units that use voltage and current inputs have transducers (Small PT's) to provide the voltage input to the trip unit and comm system, if you do not pull the isolation plug to remove them from the circuit you will fry the trip unit when you megger.


thank you zog. dont worry i wont fry anything. i will always contact the manufacturer before i megger


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## Zog (Apr 15, 2009)

electricalperson said:


> thank you zog. dont worry i wont fry anything. i will always contact the manufacturer before i megger


"The manufacturers" service group is the one that fried the trip units I was refering to. Remember, they sell the replacements. :laughing:


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## electricalperson (Jan 11, 2008)

Zog said:


> "The manufacturers" service group is the one that fried the trip units I was refering to. Remember, they sell the replacements. :laughing:


looks like im screwed. can i have your business card?


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## Zog (Apr 15, 2009)

electricalperson said:


> looks like im screwed. can i have your business card?


I won't do you any good, I am not coming up there:whistling2:

But I just PM'ed you contact info for an excellent company in your area that is certified and specializes this type of thing.


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## electricalperson (Jan 11, 2008)

Zog said:


> I won't do you any good, I am not coming up there:whistling2:
> 
> But I just PM'ed you contact info for an excellent company in your area that is certified and specializes this type of thing.


thank you zog i will use them if i ever need things tested. eventually i would like to get certified so i could do it myself


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## Zog (Apr 15, 2009)

electricalperson said:


> thank you zog i will use them if i ever need things tested. eventually i would like to get certified so i could do it myself


As of now you can only get certified by NETA, and you can only be NETA certified if you are working for a NETA company. But, the NICET electrial testing certification is coming back that will be available for individuals. 

But, be prepared to invest about a million bucks in test equipment to be able to properly test switchgear.


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