How do I trace out a circuit?
Every electrical issue is different and requires a different solution. As a building gets older it is inevitable that more and more people will have put their hands on the electrical system. Whether its to remodel a space completely or just to add a light here or an outlet there. With all these different people coming in and fiddling with the electric system there is bound to be some poor labeling and bad craftsmanship. This leaves you with the issue of having unidentified power. There may be outlets that you want to turn off or lights that you need to power down and you cant find the breaker. The easiest thing to do would be to shut everything down but that is rarely an option and fixes are typically made during the work day when people are using the space. So shutting all the lights off or cutting all the power is not going to fly and if you try and guess which breaker is the right one and turn it off there is a chance you could be cutting power to someone’s computer or something important so that is not something that you can risk either. So how do you identify an unlabeled device?
Having the right tools for a job is 90 percent of the struggle. If you have the right tool any job can seem simple, this is true with circuit tracing as well. The easiest way to trace a circuit out is to get yourself a circuit tracing tool. Here is a brand that I recommend: (Klein Tools Digital Circuit Breaker Finder Approx. $40).
These tools are most commonly used for mapping out a single circuit. They have a very simple application as well, each tool may have a slightly different process but it boils down to plugging one device into the outlet and then taking the receiver to the panel and slowly going up and down the breakers until it beeps. When it beeps you know you have the right breaker. This tool uses a frequency that it transmits thru the wire that does not affect the wire or the devices involved but effectively locates the breaker you are looking for. If you don’t have access to one of these tools or don’t want to spend the money there are a couple more techniques you can use to try and find the circuit.
Another commonly effective technique for finding a circuit is by using the color of the wire to narrow your search. If you are working with a 120/208 volt panel there is a color code that almost all electricians use when they circuit their panels. There are 5 colors associated with this voltage, 3 phase colors a neutral color and a ground color. We will start with the phase colors A phase is black, B phase red, C phase is blue. The neutral color is white and the ground wire is green. Panels are commonly laid out where the odd number circuits are on the left and the even circuits are on the right. So the left side from top to bottom will go 1,3,5,7… Where the right side will go 2,4,6,8… from top to bottom. The way they phases are laid out is similar, on the left side A phase would be circuit 1, B phase circuit 3, C phase circuit 5, then back to A phase for circuit 7 and it continues in that pattern A,B,C,A,B,C all the way to the bottom. That is the same with the right side of the panel as well. So if you can see the color of the wire for the circuit you are trying to map out you should be able to eliminate 2/3rds of the panel just based off the color of the wire. This method can be effective if the initial wiring was done by a trained and certified electrician as almost all electricians use this wire color method. But in reality it just takes one person to come in and run a wrong colored wire for this method to be completely ineffective.
If both of the techniques above are ineffective then the last option is to start shutting some power off. The best way to do this is to get yourself an receptacle outlet tester and plug it in to the outlet you are trying to identify. They look like this:
These are very simple to use and also pretty cheap (around $10). If you don’t own one I would suggest getting one just to have with you. When you plug it in to a live circuit the two lights will go on showing that the circuit is on and that it is wired correctly. The next step is to then go to the panel and start shutting off circuits. Once you flip the correct circuit off the lights on the receptacle tester will go off, then you will know that is the correct circuit. Like I said before sometimes shutting off the power isn’t an option in which case you will have to go with the two techniques I listed before this. But if all else fails this will get you the correct circuit. My suggestion would be if trying to find this circuit in an occupied space do it on off hours where shutting the wrong circuit down will not cause a problem.
In conclusion, tracing circuits is a big part of what electricians do every day. Sometimes you get lucky and a box is labeled and you can find it right away but sometimes it takes a little extra work. But if you have the right tool for the job a task like identifying a circuit can become simple. Using the color codes is a technique that should be effective if the original work was done by a skilled and qualified electrician as these color codes are almost law in the electrical trade. As we went over if all else fails and the power has to be shut off a simple receptacle tester will make it easy to know if the outlet you are working with has lost power or not. Circuits can be a pain to trace out but it’s a task anyone can accomplish if they have the tools and know the steps.