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#20115 - 01/09/03 10:31 AM Receptacle tester  
Wirenuttt  Offline
Joined: Nov 2002
Posts: 267
Had a problem at a school a couple of years ago. We had an aprentice go to all the recetacles with the plug-in tester. All rec's showed wiring OK. Most of it was in block work with a 4" sq. box above drop ceiling for termination. There was 120 for power and 277 for lighting. One of the lighting whips was mistakenly tied into the receptacle j.b.. Tester read circuit OK. This tester doesn't tell you voltage. Later on a carpenter plugged in his drill and without even touching the trigger it jumped, spun, smoked and flew out of his hand. I don't know if anything like this ever happened to anyone, but it was a bad mistake, specially in a school.

Work Gear for Electricians and the Trades

#20116 - 01/09/03 11:54 AM Re: Receptacle tester  
electure  Offline

Joined: Dec 2000
Posts: 4,259
Fullerton, CA USA
Thank your lucky stars that they didn't plug one of their new PCs into it.
Luciano, who had been a helper for more than 20 yrs, did the same thing with some 277 travellers. Fortunately, there was no V between them. In Spanish:
ya =still
no = no
Total equation = Still no lights...S

#20117 - 01/09/03 05:37 PM Re: Receptacle tester  
iwire  Offline
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
I went to work in a 120/208 Panel in a large building getting near turnover.

Company policy is no live work and I happily shut down the transformer feeding the panel, checked the mains, it was dead.

I started moving some branch conductors around and Blam. Big flash. I checked my self and the coworker with me, we where fine.

What had happened was a 277 lighting circuit got tied into an outlet circuit.

The 120 volt branch breaker had not been turned on so the lighting circuit was working fine along with about 6 277 volt Duplex receptacles.

We commented that at least we found it before someone plugged in a tool, now I know what would have happened if they did [Linked Image]

Seriously, now I check all terminals.
Take nothing for granted.

Bob Badger
Construction & Maintenance Electrician

#20118 - 01/09/03 05:59 PM Re: Receptacle tester  
Bjarney  Offline
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
iwire — One more reason it pays to be proficient with a non-contact ac voltage tester. {e.g., Greenlee, Fluke "pen" tester}

#20119 - 01/09/03 06:10 PM Re: Receptacle tester  
iwire  Offline
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Very true, the company I work for gives them out like candy.

If I am on the clock I have one with me.

The down side, more then once helpers in the company can not seem to remember they do not work on MC etc. [Linked Image] Then they cut into live MC.

But they remember after that!

Bob Badger
Construction & Maintenance Electrician

#20120 - 01/09/03 09:43 PM Re: Receptacle tester  
John Steinke  Offline
Joined: Apr 2001
Posts: 518
Reno,Nv., USA
This brings up the problem of mixing voltages on neutral wires. We have got to start identifying our neutrals as well as our hots!

#20121 - 01/10/03 02:12 AM Re: Receptacle tester  
NonLinearLoad  Offline
Joined: Mar 2002
Posts: 53
McHenry, IL. USA
As for the plug-in testers, the only people I see use them are home inspectors by us. Unfortunately, the readings they get with them cost some poor homeowner a service call by me. The results they get just don't seem to be correct very often.

If an electrician can't figure out how to use real testers, they should do some other kind of work. And it doesn't look to professional walking around with one of those either.

I will use one to try and cypher what a home inspector was getting as far as eroneous readings.

If a receptacle had a ground wire from a box tied to the ground screw, and also to the neutral screw, would not the readings be correct on the tester? And no neutral in the box to begin with.

Then comes the voltage issue, real testers will show it is more than 120V.

Now, you folks bring up the issue of lower and higher voltage in incorrect locations. I always make sure that the two shall never meet. 208/120 in it's own runs, 480/277 in it's own runs. Indicating the higher voltage on j-boxes in some locations as a safety precaution for future reference is sometimes nice too.


#20122 - 01/10/03 06:46 PM Re: Receptacle tester  
golf junkie  Offline
Joined: Apr 2001
Posts: 507
York, NE
"This brings up the problem of mixing voltages on neutral wires. We have got to start identifying our neutrals as well as our hots!"

We use gray for 277v neutrals and white for 120v. This is standard practice around here, I just assumed that everyone did this.

And like NLL said, it's better to keep the piping separate. Allthough I will cross systems where necessary to keep the pipework neat.


[This message has been edited by golf junkie (edited 01-10-2003).]

#20123 - 01/10/03 07:19 PM Re: Receptacle tester  
iwire  Offline
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
NonLinearLoad, I might be missing something obvious, but how would "real testers" find the problem you describe any more then the "Snake Eyes" tester.

I have a few different meters and "wiggys"
But I always have a receptacle tester it's fast and efficient when checking large numbers of outlets. Luckily 277 volts at the receptacle is rare.

And on the keep it separate, well that would be the intent [Linked Image]

Bob Badger
Construction & Maintenance Electrician

#20124 - 01/10/03 09:22 PM Re: Receptacle tester  
Wirenuttt  Offline
Joined: Nov 2002
Posts: 267
I think where the problem is as first mentioned, it was a whip that tied into a rec. j.b.. There was a lighting j.b close and the two whips were crossed. All the conduits were separated, the J.B.s were all marked for circuits and voltages. But all the M/C looks the same. Is there M/C available where the outer jacket is colored to signify voltage? This has only happened once that I've seen or heard about.

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