Electrical circuit troubleshooting?

[farmerbw]

I'm looking for some recommendations on what might be causing this and possible solutions.

We've got an undergound/wireless dog fence (I'll omit the dist/brand info as I don't really think it's pertinent) that we've had for almost 3 years. Up until recently it's been pretty problem free but starting back a couple of months ago, maybe April, we've been having some issues with the controller "frying". Unfortunately we're on the 4th replacement controller since then and it just went out over the weekend after being installed back on 8/1. After the 2nd replacement went out after a couple of weeks the rep came out to install the 3rd replacement himself since he was concerned about how many he'd replaced in a short period of time. The new control unit he brought "popped" as soon as he plugged it in, so he really wasn't pleased at all. He took the 2 dead units and was going to have them examined by their techs to see if they could find out what was blowing them. The fourth/current unit he shipped to me to use while they checked out the other two and I hooked it up. The also provided me a free PanaMax underground fence surge protector to hopefully prevent further issues since they're convinced a surge killed all the units.

A history of what's been done/not done.

1) All the controller unit transformers have always been plugged into a surge protector. In fact I've used 2 different ones in case there was an issue with one and that had no effect.
2) The units transformer has always been plugged in the same 110v garage outlet since it was installed.
3) My irrigation controller, which is fairly sensitive itself, is plugged into the same outlet and most of the time in the same surge strip (or none at all) and is still working fine.
4) The Panamax fence suppressor protects against surges from both sides of the unit (house current and the buried wire antennae) and is supposedly one of the best on the market with a very low failure rate.
5) The techs finding was that the two units he checked were both fried by a house side surge and not a fence/antennae side surge.
6) The 4th unit and PanaMax protector were installed with the old/original power pack/transformer since they didn't ship me a new one of those like they indicated they would. I think this might be where the problem lies.
7) This circuit is shared by some of my ww'ing tools when used, but I've not tripped a breaker or had any issues with the tools. I run the Delta contractor TS and Jet 1.5 hp DC at the same time off that circuit but haven't seen any issues there.

The rep obviously is tired of replacing the controllers at no cost under warranty, as are we since it means the fence doesn't work while we're waiting for them to provide replacement parts. He thinks we should have an electrician come out and investigate our home wiring for a "surging issue", but I'm not sure if that's needed or what I would ask them to check since nothing else on the circuit seems to have an issue. They're sending someone out tomorrow with a new controller and power pack/transformer and they'll install this one and test it.

Questions/concerns:
1) Shouldn't the surge protectors have in theory prevent any house side surges from getting to the controller?
2) It's odd that there have been failures now on 3 separate surge protectors.
3) Is it possible that the power pack/transformer was messed up by a surge during the first failure and it's now what's causing the surge to the controller since it's all that is between the surge protector and the controller?
4) I've offered to try plugging the unit into another 110v outlet that's on another circuit, in fact it's on anther service panel, hoping that will solve the issue or at least rule out something else. Think will help any?
5) Should I be considering calling an electrician to check the garage circuits or would that be a waste of money since nothing else in the house or on that circuit is having any issues?

I'm open for any suggestions on causes or solutions.

TIA,
Brian.

 

[ehpoole]

If I understand correctly from your description, this unit includes a seperate (external) power supply (wall wart or brick). Is it the power supply that is frying, or the actual controller? Generally, if the issue is a surge in your household supply killing the unit, the power supply should also fry IF it provides the voltage regulation -- if it is only a simple transformer then you would expect to see failure of the voltage regulation circuit within the controller.

That said, if this device is well engineered, its power supply should be able to handle modest surges without damage.

I've never used one of these invisible fences before (I have objections to invisibly shocking animals -- just a personal thing) but it is my expectation that the buried line is just an antenna. As such, if any other buried AC lines (e.g. electrical, telephone [ringer], or even solenoid control lines for an irrigation system) come in direct contact with the antenna wire, then they will backfeed current back into the controller which will result in failure if the current/voltage is great enough.

To really pinpoint the source of your problem we would need a failure analysis of the controller as there are many possible causes (including surges, poor design, improper installation, etc.). Only a proper determination of the failure mode will point conclusively towards what is killing the unit.

A remote possibility, and one that should cause you other problems (including flickering lights and other failed electronics) is a fault in your home's neutral line (on the utility side, or between subpanels), which can result in wide voltage swings (from 0-240v on your 120V circuits). Like I said, if this were your problem you should be seeing other odd electrical problems around your house.

 

[Alan in Little Washington]

As best I can tell it sounds to me like the separate power supply is intermittently bad, but it could be other things as well like mentioned in the previous post. For peace of mind and to ensure you continue to get warranty service I would bite the bullet and have an electrician check out the service.

Be aware, the "circuit" could be good, but it could be something as simple as a loose screw and wire on the side of the outlet that has, over time, become carbonized and making a poor connection. Now, due to vibrations, etc. it is causing brief, intermittent over current-conditions. I fixed a neighbors wiring who had a similar situation. The wire connected to the outlet which had be reduced in size due to some minor arcing and sparking, eventually melted as did about two inches of insulation without popping the breaker. Similar situations used to be quite common in houses wired with aluminum wiring. The aluminum would oxidize around the copper screw terminal and create resistance which caused the current to go up and the wiring to heat up- remember wiring can heat up without tripping the breaker- think toaster.

 

[farmerbw]

Ethan, the failure is the circuit board of the controller itself and not the power supply/transformer. All the rep told me was that their tech located the failing circuit board component on the two units he checked and determined that it had failed due a surge coming from the household current side and not the wire/antennae side. He didn't tell me what purpose that component served. The power supply I have now is the original one that came with the initial unit and has been used on every failed controller/circuit that we've had, even though they were going to give me a new to go with the new unit and surge protector that I installed. I was wondering if it was possible for the power supply to have been damaged way back during one of the 1st failures and that was causing it to produce the surge that was causing the problem.:dontknow:

You mentioned that a neutral line issue may present itself in other problems house wide and it got me to thinking. While there are no real "problems" per se, our house (heck the entire neighborhood) does experience quite a few power "bleeps" which aren't always enough to reboot computers or reset clocks. We see them more during storms but even during "normal" weather we probably see one occurrence at least every or every other week. We started having these back when the last section of our neighborhood was being built and while it's gotten a little better since construction finished 2 years ago it hasn't gone away. We called the power company several times and every time they claim they found nothing to cause it and if it was the construction there was nothing they could do about it. Any chance that some long term effects of those power bleeps could be starting to manifest themselves or is that maybe a symptom of a bigger problem and not really the power feed?

Alan, you also made some interesting points and I could check a few of them myself. The more I think about it the more I'm inclined to have it checked just for the extra peace of mind. I'll have to check but I believe I still have warranty coverage in place for electrical and if so I would only be paying a small trade/service fee so that would make the decision easier.


Thanks guys,
Brian

 

[aplpickr]

There are recording volt meters that can record surges that last less than one sine wave oscillation of the incoming A/C. Not every electrtician has one because they are are upwards of $1K. Find an electrician, perhaps industrial, and check the incoming power. This should prove who's fault it is. Good luck.

 

[ehpoole]

Check the nameplate for your power supply. It should list an input of 120V AC (or 100-240VAC or the like) and an OUTPUT of either AC or DC. If the power supply's output is anything DC then it is the primary power suppy and voltage regulator for your controller. If it is AC then it is just a simple transformer and the voltage regulation is in the controller.

If your power supply's output is DC then it should be at the very TOP of the list of suspects. Why? Because it is the one component of your invisible fence system that has been consistently present for every single failure. There is a very high (not absolute) probability that it is the source of your failures. Under normal circumstances a power supply should last 10-15 years before its probability of failure escalates unfavorably (usually due to deterioration of the electrolytic capacitors), however any device can fail at any time either due to poor design, inferior components, or unforeseen environmental events (e.g. lightning, etc.).

I would pressure them to replace your power supply immediately (well, earlier than immediately if your time machine is working order) before I spent money on a utility power audit. Even if you replace the power supply and your current controller dies, it may have been from damage acrued while still using the old power supply. On the other hand, if you replace the power supply and you stop frying controllers, then you know you've found your culprit. The technician SHOULD have insisted on replacing the power supply BEFORE he activated your present controller since the power supply was a consistent presence for each and every controller failure.

I would not invest in a utility power audit at this time UNLESS you are encountering an unreasonable number of failures in other household appliances and electronics. Dirty utility power is the norm for much of our country, that is why some of us (particularly those of us with servers and important computer systems) literally invest thousands of dollars in UPS (Uninterruptible Power Systems) and surge suppression equipment. To protect our electronics, my house easily has several thousand dollars worth of surge protection for everything from incoming utility power to telephone, cable, and antenna.

If you are experiencing issues with respect to unwanted computer reboots and crashes due to power transients I would strongly recommend investing in atleast a modest entry-level UPS for your most important (or sensitive) computers (my preference is for APC's line of UPS's -- especially their Smart-UPS series, but even their inexpensive entry-level Back-UPS line will serve your needs). I would also strongly suggest investing in TrippLite IsoBar surge protectors (especially their 'Ultra' line) for all your important electronics (the best models have aluminum chasis so they do not explode and/or start a fire when hit by lighning the way plastic surge protectors tend to). The TrippLite IsoBar protectors provide excellent surge protection and EMI/RFI filtration of electrical noise.

As for your power "bleeps", I have lived in a good many places during my life, from urban to rural and they are far more the norm than the exception. A power transient every day or two is actually pretty decent by most standards based on my experience. I have lived in rural areas where an actual power outtage every other day isn't unusual. In most cases, particularly in urban and suburban locales the cause can be traced to large commercial or industrial customers switching equipment -- or entire plants -- on or of. It can also be caused by utilites switching power generators on or off the grid as well as routine switching within your local grid. They are also frequently caused by more mundane circumstances such as untrimmed vegetation and self-exterminating pests.

With regard to a floating neutral, it will usually manifest itself as significant fluctuations in voltage for your 120V appliances and electronics, depending on the quality and resistance of your home's bonded earth-ground. You'll typically see frequently (if not continually) flickering lights and electronics either locking-up or outright frying throughout your home (i.e. not isolated to a specific device). Your 240V appliances (central A/C, heat, water heater, etc.) will continue to operate normally since they do not reference the neutral. Such a fault can be intermittent (for instance it may come and go depending on cable or junction temperature), but, again, does not limit itself to picking on a singular 120V device since it is a house-wide issue.

I hope this helps, let me know if you have any other questions or concerns. Regardless, get that power supply replaced immediately!

Take care!

 

[farmerbw]

Ethan, thanks for all the information. :icon_thum I clarifies some things for me and puts others in perspective, now to decide how to use the info!!!! :gar-Bi

I checked the power supply and it's AC it turns out.

Their field tech/installer, not to be confused with the tech that analyzed the failed controllers, is coming by later this morning to install a new controller and power supply. He is also going to make sure the PanaMax fence surge protector is correctly hooked up as well. They were initially were going to send me the stuff to install again myself but changed their minds. I'm guessing they changed their minds since they think it's possible that I'm hooking something up wrong and causing the problems, so having their tech do it this time would remove me from the equation! :gar-Bi

I've asked them to keep the unit powered from the outlet it's always been on since moving it to the other circuit on the different panel would require dropping an extension cord from the ceiling outlet and I'm not really fond of that. I guess in the event of another failure I'd have to either have them try that outlet or bite the bullet and get the circuit/service checked, which I may go ahead and do anyway. :eusa_thin

Thanks again for sharing all the information and suggestions, it's helped a lot.

Brian.

 

[jhreed]

Suggestion, they make a dog fence that works off of a radio frequency transmitter. Does not require any wire or digging. The strength of the radio signal is variable so you can set the limits to suit the available landscape. Also, it is portable. unplug it and take it and your dog on vacation. Otherwise it works similar to what you have, beeps as they approach the limit and if they go further, it reminds them.
James

 

[farmerbw]

James, we've actually used one of those on a stray we keep for a while until we found it home. They work ok for small areas and larger ones where you can put the unit in the center of the area you want to cover. We wired about .8 of an acre on very mixed terrain and crossed the creek in two spots so the portable wasn't really an option unfortunately.

The controller and power pack were both replaced today and the fence is functional again. Now to decide whether or not to call an electrician.............

Thanks every for the responses.:thumbs_up
Brian