Troubleshooting question

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gar

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EE
161007-1151 EDT

Would you find it useful to have an automatic on-off cycling load for testing circuits?

Manually cycling a load can produce the same results, but can be inconvenient, and may require two people. One to cycle the load, and the other to make measurements.

How often do you need to determine where an outlet is relative to the end of its circuit?.

How often do you need to find where a loose connection is in a circuit?

What kinds of circuit problems are most common that you encounter?

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Sounds like you are designing a new testing gizmo that would be pretty helpful.

1) Not usually.
2) HOs usually want to help us, to learn something, or to get a smaller bill. We do occasionally enlist their help. Not usually needed.
3) Very rarely
4) Often. Flickering lights or intermittent connections are a frequent problem
5) Loose connections, corroded connections, failed/failing switches/receptacles, improper wiring.

As for an automatic load, a coffee pot, sans carafe, with a timer, would work fine and cost virtually nothing from a second-hand store. Plug in, set time to x, set to auto brew x +2 min, walk back to panel, check load. Not that I keep an old coffee pot on the truck, but it would work in a pinch.
 
161008-0955 EDT

JFletcher:

Yes I am working on a design for such a device. Thanks for your input. Your response reminded me that many residential electricians probably operate as a one person crew when troubleshooting and therefore an automatic load cycler could be useful.

Your coffee pot iis interesting as a load. What is its on power load? One Internet site listed 200 W, but that seems low. The same site listed a coffee maker at 800 W, and a hot plate at 1200 W.

Presently I am playing with a Silex single element hot plate which is rated 1000 W at 120 V, and measures 950 W, 7.9 A at 120 V and 100 % duty cycle. With a 50 % duty cycle the Silex still has the same power and current at the end of a 5 second on time. I am using a Kill-A-Watt to measure power and current and for this meter to stablize requires 5 seconds. When using my Fluke 27 for voltage measurements I work with 2.5 seconds on and 2.5 seconds off.

Using an RV (Recreational Vehicle) expanded scale analog voltmeter I can usefully work at 1 second on and 1 second off, but the resolution is not adequate. This meter reads from 100 to 130 V.

I am also playing with a Pelonis 1500 W 120 V portable space heater. This measures 1457 W at 118.6 V and 12.3 A after a minute or so. This has a weird thermal or current time characteristic. It starts low (unexpected), rises to a peak, then comes down some to its steady value. Not suited for 2.5 second on and 2.5 second off times.

Dual hot plates max out at 1500 W and are bulky.

What is needed for a power load? The Silex may be fairly useful, and has moderately stable current characteristics. In some cases a 50 to 100 A load would be useful. In future comments it will be clear that a stable load is desirable.

Later I will provide some more comments.

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gar said:
161007-1151 EDT

Would you find it useful to have an automatic on-off cycling load for testing circuits?

Manually cycling a load can produce the same results, but can be inconvenient, and may require two people. One to cycle the load, and the other to make measurements.

How often do you need to determine where an outlet is relative to the end of its circuit?.

How often do you need to find where a loose connection is in a circuit?

What kinds of circuit problems are most common that you encounter?

.
Click to expand...

If you have a good idea of the number of receptacles or outlets on a circuit the Ideal Sure test can tell you the relative position to the end of the circuit. The voltage drop will increase as the cable legth increases.

When you get a larger than expected voltage drop between outlets that a pretty good sign of a loose connection.
 
gar, dunno about the coffee pot load, was just thinking IF I needed an automatic known load, a coffee pot with a timer would fit the bill. Take a sawzall to the water containing part, cut it off flush with the carafe warming plate, it would be very portable. Ugly, but portable and cheap. I'm sure they use more than 200W when brewing, especially cheap ones w/o separate circuits for the brew element and warmer plate. 800-1000W sounds right.
 
JFletcher said:
gar, dunno about the coffee pot load, was just thinking IF I needed an automatic known load, a coffee pot with a timer would fit the bill. Take a sawzall to the water containing part, cut it off flush with the carafe warming plate, it would be very portable. Ugly, but portable and cheap. I'm sure they use more than 200W when brewing, especially cheap ones w/o separate circuits for the brew element and warmer plate. 800-1000W sounds right.
Click to expand...


Just a thought. Whatever device is used to provide a load, it would likely need to be something that would be safe to leave unattended. In a way, I like the coffee maker idea, but would it be safe to leave it plugged into a receptacle in a child's bedroom for instance?
 
If this gadget works like it is advertised, it would be great for troubleshooting residential circuits.

http://www.tequipment.net/T3-Innova...NfYQE_HAnEWTIRGg4M71KlrMo92pM-EMP_xoC1yXw_wcB

Features


Works on energized cables
Finds cable length or distance to fault from one end
Measures cable distance on spool
Accuracy of 1% or better
Calibrates NVP values
Internal memory for storing most used NVP values
Large backlit LCD display
Built-in tone generator for cable tracing & identification
Loop test for continuous testing
Displays length reading in feet or meters
Auto-off to preserve battery life
 
When I worked at the University, I built a device that is capable of turning something on and off at pretty much any interval you want.

Started with an Omron h3ca-a timer, around $30 on eBay. Put it in an enclosure w/ a relay to handle the current, and added a duplex outlet half wired NO and half NC.

Timer can be set on delay, off delay, recycle, pulse, etc. A push button on the enclosure started the cycle. Front of enclosure cut out for timer to be flush. Time ranges adjustable from 0.1 sec. up to 9990 hours.

Originally built because some people forgot to turn off the coffee pot.
 
This is a common method for tracing energized circuits. A drop-light with a bulb flasher and you look for the 120V circuit with the periodic ~1A load.

When I did plant maintenance I made one out of a contactor and a small heater that I could hook to everything up to 480V.
 
A hair dryer with a stand, a heat gun, a light bulb in a freestanding fixture or a heater are all loads that can be run safely unattended and will not be too hot to put away when you are finished.

I worry about the hot plate based on what to do with them when you are finished and touch hazard while in use.
Cutting off the water tank of a coffee maker will either have too small a load or will be running the tank heating element dry.
 
ActionDave said:
:thumbsup: Sometimes it is helpful to put a load on a circuit. Either my heat gun or a 100W rough service bulb and a pig tail light socket do a good job as circumstances dictate.
Click to expand...

Yes, heat gun. I keep one in the truck to melt ice in freezers.

It also works as a nice load bank that has been helpful to me for finding a lost neutral on a MWBC.
 
David Goodman said:
Just a thought. Whatever device is used to provide a load, it would likely need to be something that would be safe to leave unattended. In a way, I like the coffee maker idea, but would it be safe to leave it plugged into a receptacle in a child's bedroom for instance?
Click to expand...

Anything that generates a lot of heat in short order is going to be dangerous. I inform HOs when I open deadfronts and the like, or perform any tests, kill power, etc. Pets are a bigger concern than kids for my customers, and for me. I do not allow anyone (people) or anything (pets) in areas where I am working on exposed energized eqpt. Getting a HO to turn on a dryer or something to load test a genset is a completely different animal.

You do bring up a good point about home-made test items and liability. I try to use the HO's eqpt when possible, especially when troubleshooting AFCI circuits. My test eqpt is NOT their coffee maker, vacuum cleaner, etc.

imo, the first thing to troubleshooting is a clear idea of the problem. HOs can be the whole bag to extremely helpful to worthless, but knowing X device is new or recently worked on can save a ton of time looking for things that arent the problem. It is worth the 5-15 minute discussion to gauge the problem before diving into boxes, panels, etc.
 
gar said:
161007-1151 EDT

Would you find it useful to have an automatic on-off cycling load for testing circuits?
Click to expand...

Not for buildings. When I was working on vehicles, I used such a method in order to trace wires using a magnetic compass like tracer. Mine was home made from a head light, a flasher can and a warning beeper. It would energize dead shorted circuits enough for me to trace them.

Manually cycling a load can produce the same results, but can be inconvenient, and may require two people. One to cycle the load, and the other to make measurements.
Click to expand...

True.

How often do you need to determine where an outlet is relative to the end of its circuit?.
Click to expand...

Pretty much, never.

How often do you need to find where a loose connection is in a circuit?
Click to expand...

A very common problem that usually turns into an open connection after time.

What kinds of circuit problems are most common that you encounter?
Click to expand...

Burnt receptacles that were used as feed throughs. Switches that fail, both open and closed and in between. Burnt circuit breakers. Outside GFCIs that are either tripped and hidden, or in plain view but not functioning. Contacts in motor contactors burnt. Wire nut connections over lights burnt. Critter chewed conductors. Bad neutral connections. Fortunately, not so common, failed splices buried in walls.
Click to expand...
 
I don't like to load up questionable circuits due to the few burnt, buried splices I have seen. A heavy load may cause a fire in a wall. I have several techniques, and some tracer type equipment and so far I have never seen a reason to have to load up a circuit with anything more than my solenoid tester.
 
iwire said:
No one is saying leave the load on and walk away.
Click to expand...

I understand that. If a heavy load is needed to do a test that a light load, like a solenoid tester, isn't sufficient for, that tells me there is a bad connection somewhere. I know for a fact that loading up a poor connection will cause heat, sometimes enough to start a fire. I have seen these buried in walls and ceilings. I don't want to start a fire, so I use different methods. So far, so good.

If you desire to do differently, that's fine with me.
 
K8MHZ said:
I understand that. If a heavy load is needed to do a test that a light load, like a solenoid tester, isn't sufficient for, that tells me there is a bad connection somewhere. I know for a fact that loading up a poor connection will cause heat, sometimes enough to start a fire. I have seen these buried in walls and ceilings. I don't want to start a fire, so I use different methods. So far, so good.

If you desire to do differently, that's fine with me.
Click to expand...

I know its fine with me.:)

It's also fine with me if I think you are overplaying the danger here. :D
 
iwire said:
I know its fine with me.:)

It's also fine with me if I think you are overplaying the danger here. :D
Click to expand...

I found this about a year and a half ago. Intermittent power to a couple rooms in the house. The tape I busted off was mostly char. This was buried in a fake ceiling joist.

View attachment 15862

It doesn't take finding many splices like these to make a person re-think loading up a circuit to the OCPD max is a safe way to troubleshoot.

Better safe than sorry, and I found this splice without using a load more than my solenoid tester. This is not the first such splice I have found buried. It's just the best pic I have.

Edit: Take note the splice got hot enough to melt the tinning off the copper. That's not discoloration.
 
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