Megger test questions

Fire Alarm Help
1

Hey guys/gals,

New to the forum, I can’t seem to find a “search” function and am tired of flipping pages…

On my current site I am required to megger test(insulation test) all circuits, I’ve done this once before (5 years ago) but didn’t fully understand it. I understand what a megger test is, how to do it, and what the purpose of the test is. However, I can’t seem to wrap my head around what results I should be looking at. This test will be done on open wire not connected to any devices and is not a motor test.

I would assume it should never be a “blanket” number, depending on circuit length and wire size and insulation type blah blah…And a short to earth would be low ohms. So is higher the better? Should the megger read OL (over limit)?

Cliff notes: What is an acceptable Ohm range when using a megger?

I don’t mind reading if anyone has a good article or link. However, I have googled and searched multiple forums trying to find an answer and most is covering motor meggers.

2

First, welcome to the forums! :slight_smile:

I will let someone more experienced help you with the wiring test question.

But I can help you with the first question of where the search function is so you can find stuff easier. People post too many threads to scroll through manually to find one your looking for.

The search function is up in the right hand corner. :wink:

3

This link has everything you ever wanted to know, including a formula for figuring out the proper minimums that include wire length. For NAC circuits i’d just calculate it at 1000 feet, for SLC’s it could be much more.

also never test with any devices connected, you’re applying high voltage which might really mess some stuff up.

4

thanks for the replies. The link is exactly what I was looking for.

Thanks

Also, there must not be a search on a mobile device…I see it now on my PC. Thanks guys