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#203834 - 10/26/11 05:56 PM Oscilloscopes and troubleshooting
wewire2 Offline
Member

Registered: 11/14/02
Posts: 246
Loc: California
I only had a brief introduction to the oscilloscope when I was in college. Can someone describe the capabilities/value of an oscilloscope when troubleshooting building circuits? I do quite a bit of troubleshooting and have always managed with a Wiggy, receptacle tester, Amprobe, multimeter, continuity tester, tone and tic tracer. What other circuit tracing equipment do you use to make troubleshooting and tracing building wiring faster?

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#203836 - 10/26/11 07:28 PM Re: Oscilloscopes and troubleshooting [Re: wewire2]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
A scope is way far overkill for normal wiring. It might be handy if you were looking for EMF spikes but most AC wiring is so "dirty" anyway that you will always be chasing ghosts.
I love my scopes and I I try to find uses for them but it is mostly just looking at gee whiz stuff like my dimmer and CT experiments.

Now if you have a real fast scope, you can do TDR with it to find that drywall screw in your CAT 5 wink

The tool I do like in my bag is a clamp on ammeter with the capacitor checker, diode and all the VOM functions.
It is typically what an HVAC guy carries.
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#203837 - 10/27/11 07:22 AM Re: Oscilloscopes and troubleshooting [Re: wewire2]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5300
Loc: Blue Collar Country
I can't think of any use for an O-scope in a residential setting.

In certain industrial settings, the picture changes. Introduce induction heating, frequency drives, and masses of electronic ballasts to a 3-phase system, and suddenly there are things to look for.

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#203838 - 10/27/11 07:50 AM Re: Oscilloscopes and troubleshooting [Re: wewire2]
KJay Offline
Member

Registered: 11/27/07
Posts: 763
Loc: MA, USA
I donít have a traditional oscilloscope, but I do have a Fluke 123 Scopemeter that I bought about 13 years ago. I donít work on the type of equipment I used to anymore, so I find I have very limited uses for it with regular electrical work. You can use it for things like peak and nominal voltage reading, looking for waveform distortion and for extended monitoring with the software package, but I think a decent power quality meter would probably be more useful for troubleshooting building electrical systems.
I work alone often, so one tool I find that comes in handy is the Ideal digital breaker finder. It saves me a lot of trips back and forth or up and down stairs to the panel to shut off a circuit.
Of all the other various fancy circuit tracers, locators, TDR, cable and network testers that I have, I still find that my trusty Fluke 337 clampmeter, cube tester and PE/Tempo toner/filter probe set are my go to tools of choice the for majority of circuit tracing and troubleshooting issues.

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#203844 - 10/27/11 11:15 PM Re: Oscilloscopes and troubleshooting [Re: wewire2]
wewire2 Offline
Member

Registered: 11/14/02
Posts: 246
Loc: California
I was working on installing some play area lighting at a Mcdonalds a long time ago and another electrician showed up to trace some underground wiring to a monument sign that had lost power. He had an oscilloscope, the kind that looks like a small TV. He said he was able to determine the length of the wire between his connection and the nearest splice by the waveform on the screen. I was impressed! Didn't stick around long enough to see whether he found the bad connection or not.
Thanks for the replies!

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#203845 - 10/27/11 11:29 PM Re: Oscilloscopes and troubleshooting [Re: wewire2]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9012
Loc: Estero,Fl,usa
That is the TDR (Time domain Reflectometry) thing I was talking about. It really does work if you have a fast enough scope. You are parsing nanoseconds. Generally you use a purpose built machine but I have had pretty good luck with my 465.
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#203879 - 10/29/11 03:01 AM Re: Oscilloscopes and troubleshooting [Re: wewire2]
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8530
Loc: SI,New Zealand
Originally Posted By: wewire2
I only had a brief introduction to the oscilloscope when I was in college. Can someone describe the capabilities/value of an oscilloscope when troubleshooting building circuits? I do quite a bit of troubleshooting and have always managed with a Wiggy, receptacle tester, Amprobe, multimeter, continuity tester, tone and tic tracer. What other circuit tracing equipment do you use to make troubleshooting and tracing building wiring faster?


Mate, you need to understand what a "scope" is used for.
Pretty much, if you've been told that they can do any more than measure voltages/currents versus time, you have been lied to.
As that is inherently what an oscilloscope does.
I own two 'scopes, one is a cheap DSE model that is only good for a ball-park idea, the other is a Tek-tronix model that I've owned for 25 years.

You can't merely bank large voltages onto the input of a 'scope, this will kill it, no matter what attenuation you have on your probe.

I don't think personally that a 'scope is a bit of test gear that an Electrician needs, unless they are doing Industrial problem solving.
Drop an old school CRT scope and you've pretty much got a box of broken glass.


Edited by Trumpy (10/29/11 03:52 AM)
Edit Reason: Added new stuff
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#204045 - 11/05/11 10:33 AM Re: Oscilloscopes and troubleshooting [Re: wewire2]
KJay Offline
Member

Registered: 11/27/07
Posts: 763
Loc: MA, USA
I forgot to mention that another possible use for the Scopemeter would be if you work on some types of generators and need to adjust the initial output voltage and frequency or test it under load. You can view frequency, voltage and waveform changes all at once on the same screen, which is handy.

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#204066 - 11/06/11 08:29 PM Re: Oscilloscopes and troubleshooting [Re: wewire2]
SactoCliff Offline
Member

Registered: 08/04/09
Posts: 13
Loc: Northern California
wewire2,

In addn to the things you mentioned, I've found that a voltage drop tester (the Ideal Sure Test, or Tasco model, and now Amprobe has one), is very valuable.

It loads a 15 or 20 amp branch circuit with a 12 amp load for 8 cycles, measures the voltage drop, and calculates the percentage voltage drop. It also calculates the impedance of each conductor. It does other stuff too.

It's great for finding a weak connection in a circuit. Measure voltage drop along a circuit (guessing on the layout), when voltage drop increases dramatically, that's where the bad connection (or damage to the conductor) is.

Also, for troubleshooting intermittant problems, I've found the Fluke 189 (now the 289) very valuable. Either is a recording DMM. There are other manufacturers that also make recording DMMs.

Lastly, I'm finding the new Fluke 381 amp-clamp with the removable / remote display is a real useful tool. It uses bluetooth to link the meter with the display. Good to 50 feet in the open.

I've recently heard about a DMM called Redfish that uses wifi to send the data to your iphone or ipad. Good to 100 feet they say. Pretty pricey for a basic DMM, though.

Cheers,

Cliff

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#204067 - 11/06/11 08:31 PM Re: Oscilloscopes and troubleshooting [Re: wewire2]
SactoCliff Offline
Member

Registered: 08/04/09
Posts: 13
Loc: Northern California
One more thing (like Columbo)--

for tracing circuits, nothing beats the Ideal suretest tracer. The cadillac version with the clamp-on signal injector is about a k-buck, and worth it.

Tasco instruments has a new tracer that's real good, and about half the price of the Ideal.

Cliff

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