Megger and AFCI

[sfav8r]

I watched a guy megger an AFCI circuit today. He was measuring from a j-box inside an apartment (ungrounded conductor to ground) and had disconnected the neutral wire from the AFCI breaker but left the ungrounded conductor connected to the AFCI. He kept showing an unsatisfactory reading and I suggested that he needed to remove the AFCI completely (IE take off the ungrounded conductor). He said that it wasn't necessary because the neutral had been removed.

I didn't argue with him because it really didn't concern me, but after he left I disconnected the wire and the circuit was over 100M. I didn't try it with the wire connected to check again because I have been under the impression that testing it with the AFCI in the circuit could (probably would) damage the AFCI. Can anyone confirm this?

Thanks

 

[Cow]

I don't know the answer to your question, but when I megger AFCI circuits I isolate everything from the breaker.

 

[ELA]

You had disconnected the load neutral and left the bus neutral connected?
if so then most likely the MOV inside.
The megger is enough voltage to breakdown the MOV connected from Hot to Neutral. Then the circuit completes via the bonding jumper.

 

[480sparky]

It all depends on what voltage the megger was producing.

 

[acrwc10]

That was not too smart, most likely the AFCI was damaged. Have you tried pushing the test button on the AFCI to see if it operates ?

 

[sfav8r]

You had disconnected the load neutral and left the bus neutral connected?
if so then most likely the MOV inside.
The megger is enough voltage to breakdown the MOV connected from Hot to Neutral. Then the circuit completes via the bonding jumper.

No, I watched someone doing it and my question was, did it likely damage the AFCI. I assumed it would but have never tested the theory. I didn't notice the voltage setting he was using.

 

[ELA]

No, I watched someone doing it and my question was, did it likely damage the AFCI. I assumed it would but have never tested the theory. I didn't notice the voltage setting he was using.

I am unclear. Was the line side neutral still connected?
If so then the MOV would breakdown somewhere around 150VRMS.
Most likely the voltage setting was higher than this and thus it would cause the test to fail.

Whether it damaged the AFCI depends upon what the current limit on the megger was set to and how long the pulse was applied. My first guess would be that the AFCI survived, provided the current limit was set to a low value.