This chapter is in no way intended to be a comprehensive coverage of wiring issues but includes a discussion of a few of the common residential wiringFor more information, see the official Usenet Electrical Wiring FAQ or a DIY book on electrical wiring. The NEC (National Electrical Code) handbook which is updated periodically is the 'bible' for safe wiring practices which will keep honest building inspectors happy. manual is not what you would call easy to read. A much more user friendly presentation can be found at the CodeCheck web site: This site includes everything you always wanted to know about construction codes (building, plumbing, mechanical, electrical) but were afraid to ask. In particular, the following series of sections on Ground Fault Circuit interrupters is present at the CodeCheck web site and includes some nice A GFCI is NOT a substitute for a fuse or circuit breaker (unless it is a combined unit - available to replace circuit breakers at the service panel).

Therefore, advice like "use a GFCI in place of the normal outlet to prevent appliance fires" is not really valid. There may be some benefit if a fault developed between Hot and Ground but that should blow a fuse or trip a circuit breaker if the outlet is properly wired. If the outlet is ungrounded, nothing would happen until someone touched the metal cabinet and an earth ground simultaneously in which case the GFCI would trip and provide its safety function. See the section: "Why a GFCI should not be used with major appliances" for reasons why this is not generally desirable as long as the appliance or outlet is properly grounded. However, if a fault occurs between Hot and Neutral - a short in the motor, for example - a GFCI will be perfectly happy passing almost any sort of overload current until the GFCI, wiring, and appliance melts down or burns up - a GFCI is not designed to be a fuse or circuit breaker! That function must be

GFCIs typically test for the following condition: 1. A Hot to Ground (safety/earth) fault. Current flows from the Hot wire to Ground bypassing the Neutral. This is the test that is most critical for 2. A grounded neutral fault. Due to miswiring or a short circuit, the N and G wires are connected by a low resistance path downstream of the GFCI. this case, the GFCI will trip as soon as power is applied even if nothing is connected to its protected (load) circuit. To detect a Hot to Ground fault, both current carrying wires pass through the core of a sense coil (transformer). When the currents are equal and opposite, there is no output from its multiturn sense voltage winding. occurs, an output signal is produced. When this exceeds a threshold, a circuit breaker inside the GFCI is tripped. GFCIs for 220 VAC applications need to monitor both Hots as well as theThe principles are basically the same: the sum of the currents in Hot1 + Hot2 + Neutral should be zero unless a fault exists.

To detect a grounded neutral fault, a separate drive coil is continuously energized and injects a small 120 Hz signal into the current carryingIf a low resistance path exists between N and G downstream of the GFCI, this completes a loop (in conjunction with the normal connection between N and G at the service panel) and enough current flows to again trip the GFCI's internal circuit breaker. GFCIs use toroidal coils (actually transformers to be more accurate) where theac unit installation core is shaped like a ring (i.e., toroid or doughnut). ac unit foundation and efficient for certain applications. stand up ac unitsFor all practical purposes, they are just another kind of transformer. If you look inside a GFCI, you will find a

pair of toroidal transformers (one for H-N faults and the other for N-G faultsThey look like 1/2" diameter rings with the main current carrying conductors passing once through the center and many fine turns of wire (the sense or drive winding) wound around the toroid. All in all, quite clever technology. The active component in the Leviton GFCI is a single chip - probably a National Semiconductor LM1851 Ground Fault To detect a Neutral to Ground fault there is a second transformer placed upstream of the H-G sense transformer (see the illustration of the internal drive signal is continuously injected via the 200 T winding which induces equal voltages on the H and N wires passing through its core. * If N and G are separate downstream (as they should be), no current will be flow in either wire and the GFCI will not trip. (No current will flow in the H wire as a result of this stimulus because the voltage induced on both H and N is equal and cancels.)

* If there is a N-G short downstream, a current will flow through the N wire, to the G wire via the short, and back to the N wire via the normal N-G connection at the service panel. Since there will be NO similar current in the H wire, this represents a current unbalance and will trip the GFCI in the same manner as the usual H-G short. * Interestingly, this scheme automatically detects a H-H fault as well. unlikely situation could occur if the Hots from two separate branch circuits were accidentally tied together in a junction box downstream of the GFCI. It works the same way except that the unbalance in current that trips the GFCI flows through the H wire, through the H-H fault, and back around via the Hot busbar at the service panel. Of course if the two Hots are not on the same phase, there may be fireworks as well :-). Go to [] segment Go to [Table 'O Contents] Quality ProsGuaranteeContact UsImportance Air Conditioning Filter UseYour air conditioner delivers important comfort during the cooling season, helping to keep your home temperature and humidity levels comfortable.

If the prospect of living without your AC is more than you can handle, it’s a good idea to maintain your air conditioner regularly to make sure it keeps humming along. Check out the Energy Star website for useful heating and cooling information that will help you maintain your appliances. You’re likely to notice reduced efficiency and higher cooling costs if you don’t check your cooling unit regularly. You’ll quickly realize the importance of air conditioning filter use when your cooling bill rises or your family starts getting sick. Changing the air filter shouldn’t take more than a few minutes of your time and then you’ll have the peace of mind to run your air conditioner as you need it.There are specific factors that determine how often you should change air conditioner filters. If you have pets or if someone in your household smokes, your air conditioner filters will need more frequent changing. If you have family members that suffer from asthma or allergies, you’ll need to keep the filter impeccably clean to make sure you’re filtering out contaminants and allergens.

In addition, the time your air conditioner spends running also affects how often you need to change the filter. If you run it 24/7 during the cooling season, you’ll probably need to change the filter every three weeks. If you run it less often, you may be able to get by with changing it every five to six weeks. An air conditioner clogged with debris from a dirty air filter won’t operate efficiently. Your unit will need to work harder to produce less cooling, an unpleasant situation for your wallet. When you change the air filters on a regular basis, you’ll notice that your unit cools your home faster, which reduces the amount of time it has to run. Over time, an air conditioner that doesn’t have to work as hard will last longer with fewer repairs, too. Clean and Healthy Cooling A clean air filter will help keep your indoor air cleaner and more healthy. The EPA considers indoor air pollution to be a significant environmental problem. At the same time, an inefficient air conditioner adds additional waste into the environment, which can contribute to greenhouse gas emissions.

If you make a habit out of running your air conditioner with a dirty air filter, you will eventually notice accelerated wear and tear on the unit. Dirt that escapes the dirty air filter will restrict airflow through the unit, which can fill the coils with debris and make the unit freeze up. Eventually you also may have to replace the compressor of your unit. This will involve hiring a technician, which won’t be cheap. Air filters have efficiency values that will help you choose the best filter for your air conditioner. The minimum efficiency reporting value ranges between 1 and 12. The higher the value, the more filtration and cleaning you’ll have with the filter. Be careful, though – it will also take more power to pull air through higher-value filters. Find a middle ground in efficiency value to control energy costs. When you know you can’t be without your air conditioner to get through the cooling season, maintaining it becomes a priority to control expenses and keep it running smoothly.