Megger "Schoolin"

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Ok, I finally got a megger, a Fluke 1507. I got a good deal on it so I bought it. Been checking prices for a while and got this for a lot less than any price I've seen.

Now my problem, I have never used a megger before. I know how they work in principle, but no hands on with one.
What would be a good way to practice with it before I attempt to use it at a job? What could I use to set up some different scenarios that I might encounter?
I suppose my primary use would be on a resi circuit, but I do some light commercial/industrial jobs when called to.
 
The Biddle stuff is great. I didn't check out the link, but I think I have the hard copy.

For fun, connect the leads of your megger to your DVOM. My Megger reads exactly 500 volts.

They will poke you a good one, too. So far, no fatalities!!

I have one with a crank on it. Back when I was an apprentice, we didn't have no fancy battery powered Meggers, we had to crank em fast for a solid minute for some of our tests. One job we did was three tests per conductor on 308 conductors. We actually had to rotate crank techs on that job.

I have three, a real Megger, a pristine Sanwa and the big 1000 volt cranker. I don't use them much, but am glad to have them and know how to use them. Lots of people have them and use them like ohmeters. True, they are that, but we are testing the insulation, not the conductors.

They also have a propensity to discharge magic smoke from electronics that inadvertently failed to get disconnected prior to testing.
 

hurk27

Senior Member
I would say one of the best uses I found with my megger (500 volt) is finding that pesky UF out to a pole light that wont trip the breaker while I'm their but as soon as I leave it trips, there are many problems that can be found like as said any underground feeders in pipe or not, motors, heating elements that are barely shorting to ground, any circuit that could have gotten wet, old K&T wiring you cant see and inspect with your eyes, but as also said, make sure loads are removed from the circuit or it could add to problems. oh and don't touch the leads anytime it is in the megger position. also make you a metal stick that you can just stick in the Earth for test out doors great for testing for Earth faults in conductors.
 

jeremysterling

Senior Member
Location
Austin, TX
Congrats on your acquisition. It's a great tool for electricians.

Experiment with it. Play with it. Set a piece of wire on a some sheet metal and watch the arc as you watch the reading. Drive a nail through a scrap piece of romex and check it out.

Break it out on the job site. Use it instead of the resistance function of your VOM when checking for ground faults or shorted cables.

Check out newly pulled feeders before commissioning (energizing).

Usage will bring familiarity.
 
Last edited:

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
I would say one of the best uses I found with my megger (500 volt) is finding that pesky UF out to a pole light that wont trip the breaker while I'm their but as soon as I leave it trips, there are many problems that can be found like as said any underground feeders in pipe or not, motors, heating elements that are barely shorting to ground, any circuit that could have gotten wet, old K&T wiring you cant see and inspect with your eyes, but as also said, make sure loads are removed from the circuit or it could add to problems. oh and don't touch the leads anytime it is in the megger position. also make you a metal stick that you can just stick in the Earth for test out doors great for testing for Earth faults in conductors.
Ok, time for some schoolin for me. How do you find a UF with a megger? I have a Dynatel fault locator, (mine aint this pretty...) and sometimes I have to turn it up pretty high to get a small fault. Problem is, it is an earth return machine and won't find a fault in pipe unless the conditions are perfect. How do you do this with a megger? Remember, I am not a megger pro. For the cable I test we use a thumper, and I have never tested a motor

Naturally one would think if the problem is in pipe, just pull the run out and replace. and example of my problem would be; Harry homeowner installed his own wire and used some pipe he had laying around. No 90's or any fittings, just a piece or two of pipe where it was convenient. now it is bad and he would like for me to find the bad spot. I have had many false readings with the wire in some pipe or even all pipe.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Congrats on your acquisition. It's a great tool for electricians.

Experiment with it. Play with it. Set a piece of wire on a some sheet metal and watch the arc as you watch the reading. Drive a nail through a scrap piece of romex and check it out.

Break it out on the job site. Use it instead of the resistance function of your VOM when checking for ground faults or shorted cables.

Check out newly pulled feeders before commissioning (energizing).

Usage will bring familiarity.
Thanks Jeremy, that's the kind of stuff I hoped someone would suggest!:thumbsup:
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Make a heavy pencil trace a few inches long on paper with a #2 pencil and hook the leads to the ends of the pencil trace.
One lead on each end of the trace?

I'm getin some "schoolin" alright. Between zapping my DVOM, then a cat, now paper with my face close to it. I don't know whether I'm being told to get out of trouble or into trouble!:lol:
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
One lead on each end of the trace?

I'm getin some "schoolin" alright. Between zapping my DVOM, then a cat, now paper with my face close to it. I don't know whether I'm being told to get out of trouble or into trouble!:lol:
Yes, one lead at each end of the trace. You may have to experiment with the size of the trace, with the right size trace you should get it to glow or even burn.
 
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