| This article will be a breath of fresh air | | | | 2-gauge wire, which has a constant of 11920, |
| for some of you and a gut wrenching process | | | | or a 12/2-gauge wire, which has a constant of |
| for others. Without getting too involved | | | | 7500. |
| within the process, I will say this | | | | |
| particular piece of the puzzle is designed | | | | With this information and the constants, lets |
| for the person that thinks with the left side | | | | figure a "run for fun". This example shows a |
| of your brain. Their many studies and books | | | | run for 80 feet and on the run, there are 4 |
| written about the left side and right side of | | | | fixtures that have a 20-watt lamp in each. We |
| our brains. Many people enjoy a "good" living | | | | have a total of 80 watts on a run of 80 feet |
| dealing with issues relating to the left and | | | | and 12/2 gauge wire is used for the run. |
| right side of our brains. This could be the | | | | 80-watts x 80 feet =6400, 6400/7500 |
| start of another book relating to that | | | | (constant) = .85 voltage drop. Now subtract |
| subject; however, I am not going there. Too | | | | .85 (voltage drop) from 12 (amount of volts |
| keep this to the simplest form I can, I will | | | | from source) and we have a resulting voltage |
| say our brain is divided into two sides. We | | | | reading of 11.15 volts. I like to keep lamps |
| have the left side and the right side. | | | | in a range of 10.5 volts to 11.7 volts for |
| | | | peak performance; therefore, the reading of |
| The left side of the brain functions by way | | | | 11.15 volts fits very will within the range. |
| of using logic, facts, knowledge, math and | | | | The main thing to remember is to choose the |
| science and is detailed oriented. If you fall | | | | lamp you want and need to do the job you |
| into this category, you will enjoy this | | | | want. Once you decide on the lamp, engineer |
| article. Meanwhile, the right side of the | | | | the system to supply the proper voltage to |
| brain functions by using feelings, images, | | | | the lamp. |
| symbols, sees the "big picture", is very | | | | |
| imaginative and believes things are possible | | | | A rule of thumb on sizing wire for runs is to |
| by taking risks. If you fall into this | | | | always go bigger if there is some doubt. The |
| category, I hope your partner is a left-brain | | | | 10/2 gauge wire expense is just slightly |
| person. This article will be dull and boring | | | | higher than the 12/2 gauge wire; however, the |
| for you even though it is an extremely | | | | peace of mind is well worth the difference. I |
| important process for you to achieve your | | | | have included a flowchart to use as an |
| "big picture" on your home to create the | | | | estimate on which gauge wire to use on which |
| "WOW" effect you want. | | | | run. This does not replace the voltage drop |
| | | | formula and measuring every lead to every |
| My wife and I are a good team because she is | | | | fixture using a multi meter to get the proper |
| a professional photographer, thus a right | | | | reading. For runs over 100 feet I recommend |
| brain person. I am a left-brain person. We | | | | using the 12/2 gauge cable just because it |
| compliment each other and guess who takes | | | | can handle more with less voltage drop. |
| pictures of my landscape-lighting | | | | QUICK WIRE SIZING GUIDE: Use the guide to |
| installations. A good starting subject for | | | | select wire sizes for each run - "Are there |
| this article is "voltage drop". Voltage drop | | | | more than 100 watts lamp load on the run"? If |
| is created by internal resistance to the flow | | | | your answer is, yes then you Use #10-2 / If |
| of electricity through electric wire or | | | | your answer is no then the next question is |
| cable. It is the difference between the | | | | "Is the run longer than 100 feet? If your |
| voltages at the beginning of a cable run | | | | answer is no you Use #12-2 and if its Yes |
| compared to the voltage at the end of a run. | | | | then you Use #10-2. |
| We need to compensate for the voltage drop in | | | | |
| order to keep the same voltage to all | | | | WIRE AMP RATINGS: Wire Size #12/2 100w/8.3A |
| fixtures. If we do not, the end fixtures will | | | | is recommended and the maximum is 192w/16A. |
| have lamps with low voltage and the results | | | | Wire Size #10/2 140w/12.0A is recommended and |
| will be a decrease in brightness. This is why | | | | the maximum is 288w/24A. You will notice the |
| we can see the yellow looking lights at the | | | | low chart gives the wire size with |
| end of the runs. | | | | recommended and maximum figures. It gives |
| | | | reference to watts and amps. Remember the |
| The formula for calculating voltage drop is: | | | | formula: (Amps x volts = watts Or Watts/volts |
| Total Watts x Length of Run / Cable Size | | | | = amps) you will be fine on amps using these |
| Constant = VOLTAGE DROP. You are now asking | | | | guidelines. I keep a maximum of 110 watts per |
| yourself," What is cable size constant". That | | | | run on 12/2 cable and 150 watts on 10/2 |
| is a predetermined amount and I will not show | | | | cable. I know the system is not working hard |
| the chart for the different size cables. | | | | and I feel that it will produce an efficient |
| Instead, I will share the constants that you | | | | operating system. |
| will use for your system. Use either a 10 | | | | |