Megger question.

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Saywatt

Member
Neta specs megging 600v rated equipment (ie. thhn wire) at 1000vdc, and 250vac equipment at 500vdc, but what if the wire is connected to receptacles and switches rated at 120vac?

I guess my question is, could megging through standard recept's and switches at 1kvdc damage them?
 

SG-1

Senior Member
I frequently do dielectric tests on switchgear control wiring. Many of them have standard 120V recepts & light switches. The test voltage is 1500V AC RMS for 1 min. I have never had one fail. If they have any electronics in them like a GFI, then disconnect it. To help make sure everything is shorted together close all the switches.
 

ohmhead

Senior Member
Location
ORLANDO FLA
Neta specs megging 600v rated equipment (ie. thhn wire) at 1000vdc, and 250vac equipment at 500vdc, but what if the wire is connected to receptacles and switches rated at 120vac?

I guess my question is, could megging through standard recept's and switches at 1kvdc damage them?
Our megging is wire gear tranformers buss duct busses everything never had a issue you disconnect the electronic breakers and controls you megg it pull out the fuse blocks in the gear it helps with the electronic breakers kinda .

We megg with breakers off in switch gear we megg the feeders before we terminate them to breakers we must record each megg reading .

If ya megg thur breakers you get strange readings sometimes not a good test .

We dont megg a vfd or drives and such we dont megg thur breakers thats another test which is a low ohm test on contacts and such but megging is safe on just about any insulation test it really cant hurt at 1000 volts .
 

zog

Senior Member
Location
Charlotte, NC
Neta specs megging 600v rated equipment (ie. thhn wire) at 1000vdc, and 250vac equipment at 500vdc, but what if the wire is connected to receptacles and switches rated at 120vac?

I guess my question is, could megging through standard recept's and switches at 1kvdc damage them?
You are always supposed to isolate what you are testing
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
There is no issue with using a megger on a receptacle circuit with the receptacles installed. The only issue would be if you have cords plugged into the receptacles when doing the testing. The UL standard for receptacles requires that devices rated at 300 volts or less pass a 2000 volt dielectric withstand test for one minute.
 

BJ Conner

Senior Member
Location
97006
Neta specs megging 600v rated equipment (ie. thhn wire) at 1000vdc, and 250vac equipment at 500vdc, but what if the wire is connected to receptacles and switches rated at 120vac?

I guess my question is, could megging through standard recept's and switches at 1kvdc damage them?
Most (all?) is rated at 600 Volts. The utilization voltage can be 120, 208, 480etc.
 
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