标签: relief

It's autumn in New England in the United States. The leaves are turning to red, orange, and gold, my roses are in their second bloom, and it's time to remove the air conditioner from the window. On September 22, I opened the window to remove the air conditioner as I've done many times before. For the first time, the air conditioner fell out.   Too often, we focus on the latest and greatest processor, mobile device, or other "cool" product. But sometimes, simple things such as strain relief take on significance and save the day, especially for a "cool" product such as an air conditioner.   The air conditioner never hit the ground. Why? Because with my lightning reflexes, I grabbed the power cord, stopping the fall. Yes, the power cord's strain relief made the difference. There was a thud as the unit hit the side of the house, but it didn't hit the first-floor window directly below.   So here I am with my arm hanging out the second-floor window, holding onto the line cord as the A/C unit dangles. But even with two hands, I had difficulty pulling the unit up. I called for my wife, who came and helped me pull on the cord. The A/C unit came up and I pulled it in.   (Image: Illustration by Daniel Guidera)   There was surprisingly little damage. What's really impressive is that the strain relief of the line cord could hold the weight of the unit and survive the force on it. So, who is the manufacturer of this miraculous air conditioner, anyway? The brand name is Liberty, made in China. Here's a photo of the front-panel controls.     Here's the side-panel label.   As you can see, the physical damage is minimal, just a broken extension panel and a small break where the line cord enters the unit.     I simply had to see the strain relief on the power cord, so I removed the front panel. There, I could see that the strain relief was screwed into the metal chassis.     Next, I removed the control panel to get a look at the connections from the power cord to the circuits inside the unit. They were perfectly intact, thanks to the strain relief. The photo below shows the power cord connected to a large capacitor that reads "35/6 µF."   I then reassembled the unit plugged it into an AC outlet that had a dedicated circuit breaker, and turned it on. It worked, but I won't use it again in its current condition. Close inspection of the power cord revealed some damage, as the photo below shows. There's even a label on the cord telling you not to use it if the internal shielding is visible. The label says:   The conductors inside this cord are covered by shields, which monitor leakage current. THESE SHIELDS ARE NOT GROUNDED. Periodically examine the cord for any damage. DO NOT USE THIS PRODUCT in the event the shield becomes exposed.     Clearly, covering the cut with electrical tape isn't an option here. I'll need either to replace the power cord or use another air conditioner next year. I have one in a closet that hasn't been needed in this house.   What was that about leakage current? To find out, I called Tower Manufacturing of Providence, Rhode Island, maker of the power cord, and spoke to an engineer. The power cord has an LCDI (line-current detection interrupter) at the wall-outlet end. It's essentially a circuit breaker that trips based on leakage current. The LCDI cuts power to the unit if it detects about 5 mA. The engineer explained that LCDIs were developed for air conditioners. The problem grew from power cords that failed over time, sometimes causing fires. People would wrap the power cord around the unit and put it away for the winter. Over time, the cords would develop shorts. The LCDIs comply with UL 1699 .     I asked if the company manufactured assembled AC line cords or just the LCDIs. Tower manufactures line cords for several air conditioner manufacturers, some are completely assembled with terminations (spade lugs) and some without. There are plenty of online sellers of air-conditioner power cords, but Liberty is not an everyday name. A quick look at one seller didn't show the brand name. This one looks promising, but I'll have to gain access to the power cord again for another inspection of the terminations. I have plenty of time for that, given the length of winters here. But, I might just employ the unused air conditioner and let this one go (figuratively, that is). More homework is required. Next year, I'll probably install a support bracket under the unit, regardless of which one I put in the window.   This experience shows the importance of strain relief. Remember that strain relief, connectors, and even screws are important. They may not be "cool," but they can save the day.