Meggers!!!

[RichB]

Here is a question wrapped up in a bit of a vent--and TIA for letting me---And I appreciate all the info I have gotten and all the education that has come my way for all on here---
As an instructor and inspector and having been in the field since 78 I am having a hard time understanding the following,,,,

How does anyone get to be a journey plus level and NOT know how to use a megger?? I have been on jobs where there was a problem,ie, conduit dug up in several places and the contractor just came out and started splicing--and didn't even have a megger on the truck--understand this is a rather large company and has been in business for years and their electricians don't really have any idea about using a megger. When I asked if they had one they said they thought there was one or two in the company. In this instance we found bad(grounded) wiring for about 2500 feet that needed replaced and they were just going to splice it in the handholds and call it good--this was for traffic managment systems and lighting. After seeing a LOT of this in the field and , I appologize guys don't mean to PO anyone but, reading on here the questions a first year apprentice should be able to answer--geesh.

OK Thanks guys rant over--it just amazes me me that such a basic thing is, apparently, not taught!!

 

[Cavie]

Here is a question wrapped up in a bit of a vent--and TIA for letting me---And I appreciate all the info I have gotten and all the education that has come my way for all on here---
As an instructor and inspector and having been in the field since 78 I am having a hard time understanding the following,,,,

How does anyone get to be a journey plus level and NOT know how to use a megger?? I have been on jobs where there was a problem,ie, conduit dug up in several places and the contractor just came out and started splicing--and didn't even have a megger on the truck--understand this is a rather large company and has been in business for years and their electricians don't really have any idea about using a megger. When I asked if they had one they said they thought there was one or two in the company. In this instance we found bad(grounded) wiring for about 2500 feet that needed replaced and they were just going to splice it in the handholds and call it good--this was for traffic managment systems and lighting. After seeing a LOT of this in the field and , I appologize guys don't mean to PO anyone but, reading on here the questions a first year apprentice should be able to answer--geesh.

OK Thanks guys rant over--it just amazes me me that such a basic thing is, apparently, not taught!!

Started in the business at 18. Owned my oun business for 10 years. Never saw one untill I was 59 years old.

 

[K8MHZ]

I own three megohmmeters. I know many journeyman that don't know how to use them. Also, I could troubleshoot using a sensitive DVOM just as well as I could with my megohmmeters.

In their own right, megohmmeters were not designed as troubleshooting instruments, rather a tester for insulation integrity, mostly on new installations.

We spent about an hour in our apprenticeship covering megohmmeters and hi-pots. Nothing hands on. I learned to use them because I always volunteered to be on the test and troubleshoot crews.

Hi-pots are nearly a thing of the past as they are considered destructive testing. Hi-pots are being replaced by a couple new technologies and I suspect that megohmmeters will suffer the same fate once we can measure insulation integrity without putting 500 to 100 volts into a conductor.

I have a DVOM that will measure 20 million ohms. So far, I haven't been on a trouble shooting job that I would normally use a meghommeter for that the newer DVOM's wouldn't do just as well at, and at a safer voltage level.

How many journeyman know how to use a Chicago bender? Never being exposed to a certain particular aspect of our craft does not mean that a person is a lesser or incapable individual.

 

[Cow]

Our shop only had one community megger up until about 3-4 years ago. Now the guys are starting to buy them on there own, myself included. I don't know how they lived without them! Well I sorta do, there are still a couple guys who ask to borrow mine!!:roll:

That and a good circuit tracer...freaking life saver!!

 

[ptonsparky]

Many electricians are installers. That is what they were hired for and thatvis all thay want. Service techs are a different sort as are those that tackle plc or motor control. That and the boss is to cheap to supplyvevery one with a high dollar meter.

 

[cadpoint]

Can I say they didn't know the difference to know that a service or circuit is in question?

How does anyone get to be a journey plus level and NOT know how to use a megger??

The Good Book fail safe is to calc. the load, understanding this is persepction!

 

[zog]

I own three megohmmeters. I know many journeyman that don't know how to use them. Also, I could troubleshoot using a sensitive DVOM just as well as I could with my megohmmeters.

In their own right, megohmmeters were not designed as troubleshooting instruments, rather a tester for insulation integrity, mostly on new installations.

We spent about an hour in our apprenticeship covering megohmmeters and hi-pots. Nothing hands on. I learned to use them because I always volunteered to be on the test and troubleshoot crews.

Hi-pots are nearly a thing of the past as they are considered destructive testing. Hi-pots are being replaced by a couple new technologies and I suspect that megohmmeters will suffer the same fate once we can measure insulation integrity without putting 500 to 100 volts into a conductor.

I have a DVOM that will measure 20 million ohms. So far, I haven't been on a trouble shooting job that I would normally use a meghommeter for that the newer DVOM's wouldn't do just as well at, and at a safer voltage level.

How many journeyman know how to use a Chicago bender? Never being exposed to a certain particular aspect of our craft does not mean that a person is a lesser or incapable individual.

20Meg is below the minimum acceptable spec for just about everything, so I don't see how that can be useful.

 

[petersonra]

The company I work for has been in business for 25 years and just bought its first megger last week.

Sometimes it is people that are cheap.

Other times it is the lack of need.

I can't tell you how many very experienced electricians I have run across over the years who cannot read common control schematics. They either never learned or forgot how.

 

[renosteinke]

Funny you should mention meggers.

My career has 'yo-yo'ed' from lab to industrial to constrruction to service to industrial to controls to service to ... well, you get the picture. It wasn't until my second pass through 'industrial' that I actually learned about meggers.

Fast forward to a return to 'service,' and I remembered the megger. There were various instances where a multi-meter showed a wire as 'good,' yet the breaker would instantly trip. In each case, a megger immediately identified the bad wire. I found it quite useful when my first look failed to identify the problem.

Now I'm back on the 'industrial' side, and we have meggers aplenty. That doesn't mean anyone knows how to get the most from them, but at least the concept is known.

FWIW, I don't believe that the typical "inside wireman" has a need for a full-featured $$$$$ megger. A basic 'good/bad' model. like the $150 Supro with its' row of LED's for a display, should be plenty.

 

[richxtlc]

I own three megohmmeters. I know many journeyman that don't know how to use them. Also, I could troubleshoot using a sensitive DVOM just as well as I could with my megohmmeters.

In their own right, megohmmeters were not designed as troubleshooting instruments, rather a tester for insulation integrity, mostly on new installations.

We spent about an hour in our apprenticeship covering megohmmeters and hi-pots. Nothing hands on. I learned to use them because I always volunteered to be on the test and troubleshoot crews.

Hi-pots are nearly a thing of the past as they are considered destructive testing. Hi-pots are being replaced by a couple new technologies and I suspect that megohmmeters will suffer the same fate once we can measure insulation integrity without putting 500 to 100 volts into a conductor.

I have a DVOM that will measure 20 million ohms. So far, I haven't been on a trouble shooting job that I would normally use a meghommeter for that the newer DVOM's wouldn't do just as well at, and at a safer voltage level.

How many journeyman know how to use a Chicago bender? Never being exposed to a certain particular aspect of our craft does not mean that a person is a lesser or incapable individual.

The reason we use a megger is because a multimeter has insufficient voltage to stress the insulation to cause a small current to flow inorder to calculate the value of insulation. In most modern insulation the insulation is in the gigohm range. A multimeter will read good when stressed at 9 Volts, but when 100, 500, 1000 or 5000 volts are impressed on the insulation it fails. The quality of the insulation is not based on the sensitivity of the meter but how well it stresses the insulation and how well the insulation responds to that stress.
I have been using a megger for over 30 years, the one item that many people who claim to know how to use it is not knowing what the guard terminal is used for. When I explain how useful this terminal is in troubleshooting circuits by using it to isolate various parts from the circuit under test, they find it a useful addition to their testing practices.

 

[RichB]

I wasnt trying to cut anyone down and hope no one took it that way--If some did I appologize now--But, Iagree that if a megger is used properly and a baseline is started and regular testing and keeping the readings to show a trend is the best way to use a megger,,,but,,, The guys on these crews are working roadside power and their whole troubleshooting technique is usually to just splice it all back together throw the switch and see what happens--if it holds it's good if not then call the inspector and have him(me) come out with the megger and start the TS portion of the work. The way our contracts are written, it is the contractors responsibility to keep the equipment maintained and working.

And yeah I realize that if you spent all your timne running conduit and pulling wire( Read installing here) then you probably won't know much about the troubleshooting side--Just the way it =works in this bussiness--and thanks again for letting me go off the other day!

 

[K8MHZ]

20Meg is below the minimum acceptable spec for just about everything, so I don't see how that can be useful.

For troubleshooting, very useful.

For mapping insulation integrity, not useful at all. Also, the spec the DVOM falls short of is applied voltage. 500 or 1000 volts may be necessary for plotting curves, but is seldom needed for troubleshooting.

Too many guys use meggers when they aren't needed. To me, if you aren't taking periodic readings and plotting a curve, a megohmmeter or a hi-pot are not needed.

 

[ptonsparky]

For troubleshooting, very useful.

For mapping insulation integrity, not useful at all. Also, the spec the DVOM falls short of is applied voltage. 500 or 1000 volts may be necessary for plotting curves, but is seldom needed for troubleshooting.

Too many guys use meggers when they aren't needed. To me, if you aren't taking periodic readings and plotting a curve, a megohmmeter or a hi-pot are not needed.

Be glad you have customers that call you to plot curves. Most of us don't.

 

[K8MHZ]

Be glad you have customers that call you to plot curves. Most of us don't.

Haven't for quite some time. And it wasn't a customer. It was on a powerhouse build when I was a 5th year apprentice. I ended up running the test crew. We had to plot base curves for every critical conductor installed.

I liked it, thought it was great OJT. The journeymen that worked under me would have rather run pipe and not have to do print reading and math. I liked it so much that after the job wound down I ended up buying 3 meggers.

 

[hurk27]

I also have for the past 26 years worked for a shop that never has seen much less used a megger, I asked once if one could be added to our inventory and after looking up a price from the local supplier, was told we haven't needed one in all these years for that kind of money we don't need one now.

But my first experience with meggers was in industrial, and one of the best eye opener I had was when it was explained to me in how they differ from a regular ohm meter, was that if you take a set of contacts and open them about the thickness of a couple papers thick gap, and use a ohm meter, it would show all is fine, but put a 500 volt plus megger on it, and it will fail, as it would arc over, this is the same thing when you have lets say an underground feed to a post light, you ohm it out and all seems fine, turn the breaker back on and it holds, couple days later customer calls and complains the breaker is tripping again, now what happens that is so random?
Transient voltage spikes, these little spikes that motors and ballast tend to kick into the circuits can sometimes can be a few thousand volts, the bad spot in the cable starts to arc over and the current increases till it trip the breaker, but you go back there and reset the breaker and it resets, till the next inductive load is turned off, in this building or one down the street.

The funny thing is, if you would place a TVSS on this line, it probably would have never been noticed until the line totally fails, but a megger would have found it the first time.

 

[hurk27]

A good analogy was also once told to me, to explain why high resistance faults would not show up on an ohm meter but at random trip a breaker.

Think of a reservoir with a dirt dam holding back the water, the water level in the reservoir is the voltage, and the dam is the insulation, now there is a low spot at the top of the dam, a bad spot in the insulation, a surge comes along (rain storm) and this bad spot starts to trickle water, soon enough dirt is removed that the whole dam flashes over, the only problem with this is there is no breaker or fuse.

 

[stjohnbarleycorn]

I suppose meggers are not the only thing that a lot of electricians don't know about. I teach second year and a lot of the guys have been working in the field for 5 years or more, and don't know how to use a meter or what it is for, or what difference of potential is.
You can do a lot of electrical work with guessing and replacing things that don't need replacing and get away with it for a long time.

I first started using meggers in my hvac education, I do mostly service work on a part time basis now I used a megger recently on a ball field that was tripping the breaker randomly. I gave the board the info and they decided that my info was not that important. SO they will wait till the line burns through and then it will be an emergnecy . Of course this will happen in the middle of the biggest game of the year on the hottest day! It won't be me who replaces that line.

 

[knoppdude]

I only had the opportunity to use a megger several times as an apprentice in the construction aspect of the trade. As a maintenance electrician, it was probably the tool I used the most, almost daily. You can get a great deal of information from this device. I can understand how some electricians are unfamiliar with the megger. Unless you get to use one on at least an occasional basis, an electrician would not know how to use one without some type of guidance.

 

[76nemo]

Wow.....

Wow.....

Being of the somewhat younger crowd,(35), it baffles me on how many feeders were placed without initial IR testing. It's almost inconceivable to me.

I'm not a construction fella, so I might not have a say. This again just baffles me.........

 

[zog]

More stuff gets tested than some people think. While many installers have never used a megger, it is common to have a 3rd party testing company come in after they are all finished and do acceptance testing, which includes megger teseting. Grounding, transformers,cables, breakers, relays, etc... all get tested.

Most guys just don't see it because they are on to the next job.