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Discussion Starter #1
Guys, I have a potential job after a fire but don't have equipment for megger testing the property. Are there any companies offering this in Northern NJ? Thanks Pat
 

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That makes sense but then I still have no education on how to actually do the testing.
 

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Arsholeprentice
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Brian should post an 11 tips for meggering post now!:laughing:
 

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Arsholeprentice
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That makes sense but then I still have no education on how to actually do the testing.
There is only one way to learn it....do it. Have a good friend that knows how? Possibly pay him for the time to teach you on the site.
 

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That makes sense but then I still have no education on how to actually do the testing.
There is tons of info online if you are interested in learning. Definitely something every electrician (who does any troubleshooting) should know.

Google "A stitch in time" and read that for starters. However, for a fire job you mostly are going to be doing "go/no go" testing. Very basic, very easy, definitely worth investing in a megger in my opinion.
 

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Brian should post an 11 tips for meggering post now!:laughing:
I believe he already has at some point. Maybe I'm mistaken? Either way there are quite a few guys on this forum that could help the op with a "meggering for dummies" crash course if he's interested.
 

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Discussion Starter #11
Copied from recommended link. And is what scares me the most about doing this myself.
Quote:
Originally Posted by electrictim510 View Post
Whats the deal with the Extech 380260 vs the NIST certified one? Whats the big difference?
95% of my customers will not accept a test report without the test equipments NIST calibration certificate attached.
 

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There are firms in your area that would do this, if you were in southern NJ I do it for you.

Search out NETA firms.

Insulation resistance test.

The first step is to do a visual, and determine the extent of the damage. If there is damage to the NM sheathing, I would recommend replacing the NM decent megger reading or not.


Second you need to remove all the loads, smokes, door bell transformers, dimmers disosal, dishwasher, stove, light bulbs, GFCI's.

Third make sure all switches are turned on slpices made so when you test you get all portions of the branch circuit.

Then at the panel lift all neutrals,

Then test the branch circuits, (keeping it simple) black to ground, black to white, white to ground and if a multiwire red to black, white and ground.

At a minimum I would do a one minute reading.

Per NETA the readings should be 100 megohms or higher record humidity and temperature and adjust for these factors if necessary.

The NETA table and adjustment factors are all in the NETA Maintenence Standards available on line.

Document everything and if you need forms IM me here.
 

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It's simple, like using your meter on the the continuity setting but with high voltage.

Here's a quick run down.

You need to go around the house and disconnect all loads from all the circuits. Don't forget anything because the higher voltage can damage sensitive electronics and things like light bulbs or heating elements will give you bad readings.


At the panel label and disconnect all the cables you will be testing.

Using a form, record all your readings. Test for 30-60 seconds.

Example.

Bedroom circuit/ or circuit 1

H-N= x (reading in mega or giga ohms)
H-G= x
N-G= x


The specs for the job I did last required each circuit to read at over 100 mega ohms to be accepted.
 

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Ok, back on track, more about insulation testing. Don't give them the attention they want and they won't get the ego boost if it is them.

In my opinion, you are one of the most knowledgeable electrical equipment testing experts here Bad Electrician.

So, you where saying about methods of insulation testing Bad electrician?

And what brand of meter do you recommend for the humidity?
 

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That Ultrasonic tester that (whomever) mentioned was something I had never seen suggested for electrical testing. Anyone else use one? I would think for the mentioned loose connection, the IR would be a whole lot quicker. Interesting idea regardless.
 

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Neat stuff. I think I can resist my test tool addictions/temptations on this one. Cost vs benefit for me considering what I do which so far has kept me from buying any IR stuff either. Not saying its not worth it or relevant, just not justified for the work I do.
 

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Ok, took out the trash so we can move on.

Anyways, in general, after a fire you are going to deal with three major types of damage to electrical systems and equipment:

1: Heat (duh.) Even in the areas not directly involved in the fire, the radiant (or conducted) heat can be high enough to melt or compromise insulation on wiring and equipment. A megger has good chances of detecting this. BUT if the insulation on cables like NM is completely burned away, and the conductors are in "free air" or not touching each other, a damaged cable can still pass a megger inspection. IMHO ALL NM and MC/AC cables in a building involved in a fire should be replaced, I wouldn't waste the time testing them. Wiring in conduits or raceways, where the conduits or raceways can be proven to be undamaged, can be meggered and replaced only as needed.

2: Smoke damage. This can happen throughout an entire building, even from a relatively small fire. Smoke particles and residue are highly conductive (and corrosive) so ALL traces of smoke residue must be thoroughly cleaned from all wiring and equipment with solvents safe for the insulating materials used. Water and or liquid soap is NOT an acceptable cleaning agent IMHO as they will simply trigger the corrosive properties of the smoke particles. Devices such as switches, receptacles, fixtures and ALL circuit breakers exposed to smoke at all should (must) be replaced. Bolted pressure switches and breakers designed to be rebuilt can in most cases be rebuilt rather than replaced.

3: Water damage. Anything that got wet during a fire must be replaced. (Especially if it was energized when it got wet.) The water will be highly corrosive (see #2 above) and will rapidly cause rust or corrosion damage to anything it gets into. Cleaning, even with approved solvents, may not prevent future corrosion damage.

In short, IMHO it is much better to replace anything involved or near a fire, no matter what the size of the fire. (Of course, I would not suggest rewiring an entire house if there was only a small fire like a trash can fire in one room...BUT ALL devices in that room and any other that show visible smoke residue should be replaced. And any wiring in the immediate room should be visually inspected, and yes I mean open the walls in that room.)

It really depends on a lot of factors, but I would rather err on the side of caution than overlook something and have to come back for another fire repair....:eek:
 
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