Two Wrongs Produced a Right Result with this Camera Installation

By Nick Markowitz Jr.
Fire Investigator

You know how your mom and other people who care about you say two wrongs cannot make it right. Well after 45 years of being on this earth I can now finally prove them wrong. I present to you a case that definitely belongs in the X-Files.

As a trouble-shooting Electrician I usually get to see a lot of freaky things happen with how electricity can behave when codes are not followed. This time however I was the victim. I was working with the handy man for a small chain of Hardware Stores here in Western Pa, helping him with the install of several cameras and recording system as they were having a raft of thefts. It was hoped the cameras would be a deterrent. I have worked with this handy man before and his work is decent and usually to code. He had run all the wiring and hooked up all the cameras including the centralized Altronix Power supply instead of using a separate wall wart (little plug in transformer) for each camera and a Digital Video Recorder. When I arrived at the store and was getting ready to program the DVR he powered everything up but there was no picture from most of the cameras. I figured something was hooked up wrong or loose. I took out a ceiling tile to look at one of the cameras and when I touched the camera power supply wire that is 12 volts DC and ceiling grid I received a severe shock. Luckily I was not hurt or knocked off the tall ladder.

I took out my non-contact test probe and sure enough there were 120 volts present on the ceiling grid. Something was definitely wrong in the ceiling, everything was getting 120 volts through it including the cameras and power supply that at this point I thought were toast.
This was a very serious and dangerous fire condition that had to be tracked down and stopped. Carefully using my probe and a pair of walkie-talkies the handyman shut off each breaker till the condition went away. We found it was the breaker that fed the power outlets to the camera power supply DVR and cash register computers. We started taking connection points apart and chasing wires when we found several receptacles where the hot and neutral were reversed. This was allowing the Surge protectors and The UPS supplies which back up the computers to send their small voltage they normally send to ground harmlessly, to feed instead into the grid. But this did not fully explain why such a hard hit of current I received.

It was upon inspection of the camera power supply I found the culprit. Instead of just one 120 volt power supply cord coming into the unit that feeds the transformer, which feeds the rectifier which produces the DC, the handy man mistakenly had wired another 120 volt cord into the 12 volt back up battery terminals from the UPS being used to keep the power supply up during a power failure. He did not realize these back up terminals are for a small back up battery you put in the supply box not something you plug into a UPS. So I thought for sure everything was fried and $5000.00 in cameras and power supply were gone for good.

But to my surprise after redoing the wiring in the power supply properly it was still working. Altronix has a reputation for making rock solid power supply and the protective circuit in the unit prevented it from blowing up. I then started checking cameras and found them all to work as well. Luckily the handy man instead of cutting the power cord end off of the wall wart and using it on end of the power wire which is standard and accepted practice of the manufacturer, went to Radio Shack and picked the wrong end even though it looked right and soldered this on to each power wire. Since it was the wrong end it prevented the 120 volts from getting into and destroying the camera.

So as twisted as this case gets you can see how two wrongs produced the right result and even though I got shocked nothing was damaged. Wrongly wired receptacles were wired correctly and the Cash Registers Computers stopped getting the weird glitches they were suffering. In my line of work you learn something new every day and this was definitely one of those days.

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