I have seen it done many times and have done it myself. Can't find the C/B that controls the circuit your looking for, take a short pc of #12 and make a short circuit device!! Is there a device (inexpensive) that one can plug in to overload a 15A or 20A ckt to the point the C/B trips??


[This message has been edited by LearJet9 (edited 09-30-2006).]

I used to have an apprentice that used to use a pre-shorted plug that he used to plug in to trip the CB.
One day he took out the whole house when he never checked the switchboard and it had old porcelain fuses and the pillar box fuse out at the street blew first.
I made him pay for the cost of the Faultsman to replace the fuse.
I don't really like the idea of using a dead short to find a circuit, it doesn't sound too safe to me, I mean, what say the breaker that supplies that circuit is faulty and won't trip?.

Shorting the circuit isn't safe. Get a $25 circuit finder & a premade socket with pigtail clips. Now you're set for receptacles or open wiring.

Dave

I have seen circuit breaker test companies trip 800 amp circuit breakers with a load device. It was the size of a two drawer file cabinet.
I'm not aware of one for small circuits. Done the 'short the circuit' routine myself when the circuit tracer was acting up. The problem is that not all the circuit may be able to take the fault and you'll create an open in a device, box, or worse yet in the wall.
If you get on a circuit with a lot of harmonics or noise the circuit locators go bezerk.

My mom wanted a ceiling fan installed and due to her lease agreement, she had to have a maintenance man install a ceiling fan (and pay the landlord $50 for about $10 in labor and $10 light fixture that he will reuse anyways). I was over her apartment for afternoon tea after church, and I heard the maintenance guy short out the wires (The loud pop is so distinct.) I was really mad he did that, but I decided to let it go. Well, I shouldn't have. About 5 minutes later, I smelled smoke.

Apparently, a few sparks set a minor fire on the couch. The maintenance man was nowhere in sight, but I found a burnt piece of #14 on his ladder, so I presume he went to get some THHN or something to pigtail off of what was left.

We reported it immediately to the manager, and I showed him where the wire burned off. Needless to say, she ended up getting the whole job done for free and a new couch and loveseat (my Mom has a huge temper and threatened to sue... I don't blame her.) I saw the maintenance man at the day labor place the next day across from where I work, so I guess he got fired.

So, Even though there's only a slim chance of a fire from a short that lasts less than a second, I say it's not a good idea at all.

My neighbor, the head of maintenance operations at a steel mill, has a device rigged up that draws 50A @ 120V, using nichrome wire. It's about the size of a computer case, and has a momentary switch capable of 75 Amps. Still think it's better to use a circuit tracer, but his idea is better than a dead short.

Why trip it?
Will it trip? (think FPE)

Try this:

Ideal 61-534 http://www.idealindustries.com

This one is $80 @ amazon.com; I bought a similar model for about $30 at Big Blue/Orange last year....has a typical recpt. tester and a GFCI tester built in.
I have MADE a ton of money on that "investment" !


[This message has been edited by Celtic (edited 09-30-2006).]

I have seen large ground fault mains trip because someone intentionally tripped a branch circuit.I won't allow it on purpose ever.

The idea of doing this is right up there with the licking your fingers and touching the wires to see if they're hot trick.

The idea of doing it on a 277V system like Surfinsparky's talking about is absolute stupidity.

There are testers for locating circuits. Buy them...use them. This is 2006, no longer the day of the "Good Ole' Boy" stunts. Work safely and die of old age.

Those circuit "toners" are ok as long as the circuit you are trying to trace isn't ran with sheilded cable. I've ran into this many-a-time when dealing with cable trays that are overflowing with wires.

There once was a time, when many a journeyman caried some sort of hme-built contraption to do just this. Others have been known to short wires together with their fingers. There's a couple of reasons you don't see this done very much anymore.

First, let's look at the math. What is it, 746 wats to a horsepower? That means that even a household circuit can kick you with the strength of three horses- and not exceed the breaker rating.
OK, maybe not "kick." How about blowing your clever gizmo into a firey ball of plasma, in your hands, until the breaker trips, or the wire melts? Imagine the fun if it's the breaker that melts down, instead!

Now, for the past year a device has been marketed that claims to let you trip that breaker safely, as well as properly test the operation of the breaker. As you might guess, it's not cheap- price somewhere near a grand, I believe.

Toners are nice, but are much more 'art' than 'science.' I have two that I use.
Proper use of an amp clamp can find your circuits- especially if you can cycle the load.

Maybe there is something that you all should klnow about circuit breakers. The ANSI guidelines and UL tests for circuit breakers call for them to trip at a certain rating (within tolerance), reset to be used again, and trip ONE MORE TIME! Nothing in the design requires any more than that, and in fact, CBs that use bimetalic thermal trip elements build up a "thermal memory" in the bimetal strip. So one it has tripped, it will take less current to make it trip again, and less the next time etc. etc. etc. Tripping a breaker to test it by loading it is essentially degrading its accuracy, exposing the circuit to future nuisance tripping and/or failure. Testing companies use an indirect method of testing the trip settings that (hopefully) does not degrade the ratings, but even then, I have always questioned the validity of annual trip testing. In a way, I think it is promoted by the breaker mfrs who WANT you to wear out the breakers so they can sell you a replacement!

[This message has been edited by jraef (edited 10-01-2006).]

Once I found a 50A breaker (that was feeding the furnace (25A), a GP circuit (15A recepts), and a couple fixtures) by dead shorting it (at the recept.) I stopped doing it. Fortunately, no one was hurt, and it was only the second or third time I tried it. No point in getting hurt with screwed up wiring.

I have seen this done and am guilty of doing it ONCE, long long ago. After seeing one too many accidental short circuits where things have melted, "Flare marks" on the wall with pieces of what was molten copper burned into the paint, exploding plug fuses, and in one case a very small fire, I will not do it and strongly recomend against anyone doing it.
I think its taken for granted that the OCPD is going to open immediately every time, but as we all here know that is not always so. Breakers are mechanical, they can simply bind and fail to operate. Fuses are thermal but who says the fuse material is correct? Thats rare if not unheard of I know but I have seen where a set of cartridge fuses protecting a stove burned away leaving nothing but the link and end-caps, not much left of the fuseholder either, and believe me there was some serious heat! The links remained intact and the stove operated normally until the problem was detected.. "Defective fuses"? Yep, can happen!

A.D

Purchase a Circuit Tracer!!!

The time, trouble and embarassment compiled when you take out a Main Fuse, trip a GFPE protected Main, shut down an entire Panelboard, or blow sparks all over the place will cost you at least 10 times the amount of a good circuit tracer.

If a Circuit Tracer is not available at the time (can't figure why, but for the sake of discussion), then have someone plug in a Drill - like a Hole Hawg for example, and turn it on / off repeatedly.
Using a Clamp-Type Ammeter, find which Feeder the load is on (to eliminate 50% to 66% of the possible Breakers), then find the individual Branch Circuit.
Verify the find by throwing the Breaker to the "Off" position, then go to the Drill _YOURSELF_ with a _KNOWN OPERATIONAL_ Wiggy type Voltmeter to verify the outlet is indeed de-energized.

Prior to any Circuit Tracing activity, inform the Personnel of the possibility for power loss - both short time period (1-5 minutes) and long term time period (>5 minutes), so that any volitale data may be saved, and no one gets mad for data loss.

Also, double, no TRIPLE protect yourself, by applying extreme levels of LOTO, locking Panelboard doors - and rooms if possible, maybe going as far as placing "Decoys" and "Barriers" on and around the Panelboard to discourage someone from the infamous "My Calculator Doesn't Work" trick!

"Decoys" may be wires which appear to be "Live" and coming from the Panelboard - but are dead. Leave them dangling with their _Stripped and Sharpened Ends_ all around any possible place someone would put their hands to open the Panelboard.

"Barriers" may be similar to "Decoys", or may involve "Masking" the Panelboard, by hiding it with cardboard; or by placing things in the way, as to make it discouragable to the unqualified to go near it.

Included in these measures is to remove the Branch Circuit Conductor from the Breaker(s) while working on the Circuit(s), and replacing the deadfront + cover.

I wonder if trained Aligators, tied to Panelboards, would discourage the unqualified?

Scott35

Gidday Scott,
In any sort of surreal world, can you imagine a crew of Liney's throwing a bare wire over the 11kV or worse still 66kV lines to effect a disconnection before starting work?.
Not only would the explosion be huge and cause major arcing to the lines in question, but it would cause a really bad health and safety risk.
With the advent of re-closers, there would be no guarantee that the line would stay dead either.
You electricians have it so easy.

"The idea of doing this is right up there with the licking your fingers and touching the wires to see if they're hot trick."

Saw a carpenter do that when I told him to wait for me to demo an area... (he didn't want to wait) I looked over as he started pulling out switches on his own. "What the %^&* are you doing, those are still live!" I say. So the dope does just that, licks, and puts his fingers across the switch. (No load) "No they aint..." (Sometimes you just want to smack people!!!!) I was temped to stick a bulb back in the fixture and tell him to try it again....

Anyway, I saw some jerk short a circuit to find it once, and it didn't pop the CB open, it welded the conductors together, and melted most of the circuit before it eventually popped. You don't have to find a breaker if you have the opprotunity to rewire it completely....

That's an idea which occurred to me for a helpful gizmo -- Something like Scott's drill idea, but automated for one-man tracing.

Build a plug-in unit which will automatically cycle a load on and off. The load could be a few 100W bulbs, or if the duty cycle is kept down a dummy-load resistance in the box.

If you wanted to get fancy, you could make both the load and the timing adjustable for versatility. Once it's plugged in, you could then use your amp-clamp at the panel to look for the "signature" of your device (e.g. 1 sec. on at 10 amps, 3 secs. off, or whatever you've chosen).

Paul,


Excellent idea!

The load device's signature could be tweaked in Amplitude, Frequency (on/off periods, not sine waves), or both - which would make it completely unique, when used in environments having existing, non-steady state loads (like SMPS, certain heating devices, people playing "Rapid Fire Light Flasher" with an Incandescent Lamp controlled with a Decora Switch, etc.).

Going to compile a few Schematics, and maybe get around to Alpha Testing (AKA: "Smoke Test") soon!

Hope you do not mind sharing the idea?...

I am thinking about building 5 or 6 units, which could be used on branch circuits of 120 VAC to 480VAC.

For easier reckognization (sp???) of the signature load characteristics, plan to use an Analog Scale Ammeter, something with a fast recovery would be nice!

Scott35

I used to do this when I was less experienced. It's a bad practice because a) there are tools that can avoid doing this, b) if there's a large load on the circuit the arc flash could take apart an old splice and you could be there for hours looking for it, and c) because professionals just do not operate like this.

Go right ahead.

I don't know what you have in mind, but I was thinking along the lines of a simple 555 timer circuit operating either a relay or a triac to cycle the load on and off. If we don't mind the timer circuit not being isolated from the line, it could be powered directly from the supply via a bridge rectifier, series dropper, zener regulator, etc. to save the cost and weight of a transformer (although it would only need to be small and I expect you already have a few suitable types laying around in your junk box anyway).


[This message has been edited by pauluk (edited 10-04-2006).]

Pauluk
Sorry, I only speak English. That was Greek to me!! How about I have the helper cycle a ceramic heater on and off while I amprobe the breakers?

Hehe.... Just blame it on my British accent!


Yep, that would be the Fred Flinstone version but it would certainly work. What Scott and I have in mind is nothing more than a circuit which does the same thing automatically so that you can do it without an assistant.

Here's an idea for verifying your circuit is dead from a distance. Like when you're working alone.
Plug in a AC only radio into the circuit and turn it up loud enough to hear it from the panel.
When you switch off the correct circuit, the radio goes silent. Keeps you from having to go back and forth. Be sure to verify with your meter off course.

I thought I came up with a great way to make a tracer. I was going to use a multitap ballast, figured Id mount a switch on the enclosure to choose which voltage I was working with. After about 3 seconds of my brainstorm I remembered how long the lamps would take to restrike.

Kale,
They make a emergency light radio which turns on when the power goes off. That would not disturb the occupants while you are searching.

A long extension cord attached to a 'work light' is also a good idea.

We plug in X10's and have the receiver at the panel. when the power is off, the receiver indicates which one, fast, cheap,and simple.

Scott35 you could also intergate it in to a regular live circuit tracer and have it give one tone while on, and another tone while off. And also give another tone completly when there is no power to the unit, so when you get it isolated, you know you got the right on because of the new tone when you shut off the breaker....

Fluke and Amprobe should be paying us for this type of info!

e57 (Mark);

Great ideas too!!!

Looks like my prototype is becoming complex!

Scott35

1) Instead of using a 555 timer, which is based on a fairly unstable R-C time constant, use a digital counter. Count cycles on your supply line, and then all of your signal generators and detectors will have the exact same time base.

2) Consider using a nice machine detectable toggling pattern on the load, something that a digital ammeter with appropriate software could very easily detect. For example, there are standard binary digit sequences that are well known for use in spread spectrum communications systems. Different binary sequences can be easily distinguished. By turning your load on and off at for individual cycles of your AC supply, following one of these digit sequences, you would get a very well defined load pattern that was easily distinguished from other load patterns. Turning the load on and off at this rate could easily be detected and differentiated from other loads.

This toggling pattern could easily be implemented in using a cheap ($1 USD retail) microcontroller chip, driving the sort of SCR used in a light dimmer.

3) The above machine detectable toggling pattern could easily be combined with a human detectable one. Rather than flipping between 'on' and 'off', flip between switching full cycles on or switching only half cycles on, so that the human readable load changes by a factor of 2 and the machine readable load is always available.

-Jon

Every home already has one of these, it's called a clothes iron - my steam iron cycles at 1800W every 30 seconds or so - about $16 at Meijer - "signature" would be unmistakable.