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I have asked a family member to replace an old light fixture in a large walk in closet with an actual electrical strip. The house is an 101 year old craftsman. There aren't any electrical outlets in that corner of the small house. The closet(has windows so it will be my office) I will need electricity for desktop pc, printer, at least one light, and just outside the closet I need to run at least two more lamps. Is that safe? Is it too much? We won't be doing iside wiring. Again only an old light fixture that has electrity running though an old fashion "flex tube" for lack of a better word.It is on the outside of the wall. ANY precautions or ideas?

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You're going to have to provide more information. What size overcurrent device is protecting the circuit? What other loads are on the circuit? –  Tester101 Feb 4 '13 at 17:56
    
I don't know much about it? Where do I look to find out?? –  Sharon Smith Feb 4 '13 at 19:56
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This refers to a circuit breaker or fuse. They are located in the electrical panel near where the wiring comes into the house, often in the basement (or sometimes the kitchen or hallway). The size refers to amperage on a particular line and is expressed in numbers, such as 15A or 20A. The line in question is the one that serves the old light fixture. Finally, your level of familiarity suggests that you probably should have a professional or at least a very knowledgeable friend manage the project. –  bib Feb 4 '13 at 21:01
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Another issue to look into besides circuit size and connected load is equipment grounding. Unless the electrical has been redone, I suspect a house this old has no grounding conductors. Not only is this important for personal safety, but desktop PCs need to be properly grounded, as do any UPS equipment or surge protectors. –  bcworkz Feb 4 '13 at 22:48
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2 Answers 2

The best answer to this is to leave the light as a light and have a qualified electrician run a three wire circuit (hot, neutral, ground) direct to your soon-to-be office. Your modern equipment needs it and disturbing any old turn of the century wiring is asking for disaster.

Having lived in an old house with Range, Pump and four circuits, adding any extra load to an ancient system without upgrading the wiring is a good indicator for having several fire detectors located in strategic places and keeping their batteries up to date.

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Here is the problem (and its one I've run into in my own home): Those old houses were usually wired with just one or two circuits of knob and tube wiring. Then, over the years, people add to those circuits (usually overloading them) or add new circuits. Sometimes they even splice newer wire into the old stuff, so you think you're working with a new circuit when it really connects to old, crumbling, overloaded knob and tube wiring in a wall somewhere. If you can determine that your light is connected to any old knob and tube wiring (black, dirty-looking, crumbly insulation on the wires), then that is an automatic disqualification for adding anything else to the circuit. In fact, that wire should be replaced throughout the house as soon as possible. If your circuit uses newer, plastic coated wire (one black, one white, one bare copper) and you are SURE that new wire goes all the way back to the breaker box with no connections to old wire, then you can analyze your circuit to determine whether you can add more to it. Here's how:

First, go to your breaker box and turn off the breaker that controls that light. Note the number on the the switch. It's probably a 15 or a 20. This tells you how many amps the breaker is designed to let through to your circuit. Now, go through your house and figure out what stopped working (other than the one light in question) when you turned it off. Be sure to check outlets, lights, porch lights, appliances, etc. How much stuff quit working? If it was just a couple of lights, you're ok to add on to it. If it was a bunch of lights and outlets, then you're not. As a basic rule of thumb (for a DIY project, not a professional electrician) multiply the number on your breaker by 100, so it will be either 1500 or 2000. For every light bulb that quits working when you turn off the breaker, subtract 100 from that number. For the first outlet that quits working, subtract 1200 from the number (That's for the possibility of a vacuum cleaner getting plugged in to one outlet on the circuit). For additional outlets, look at what is plugged into them. Are they high power items, or just cell phone chargers, clock radios, and stuff like that? If it's just little stuff like that, subtract 50 for those outlets (in addition to the 1200 from the first outlet). Count lamps the same as a light bulb.

If a bathroom outlet stops working, don't add anything else to the circuit. If a kitchen outlet stops working, don't add anything else to the circuit. If any appliance, such as a washing machine, microwave, or space heater, stops working, don't add to the circuit.
For anything that takes more power than a light bulb or a cell phone charger, you have to figure out how many amps it draws (usually printed near the cord somewhere), take the amps times 100, and subtract that number from the 1500 or 2000 you got from your breaker. If the item tells you how many watts it draws, then divide the watts by 120 and multiply by 100 and subtract THAT answer from the total. Next, subtract 100 for each new light you want to install. Then subtract for the power your computer will use. Most computers have at least a 400 watt power supply, plus printers etc. You'll need to check yours for the exact number. If, after all of that subtraction, you end up with 100 or less, then don't add to the circuit.

If your circuit breaker is a 15, DON'T change it to a 20 to get more power! It doesn't work that way. If it's a 20, be sure to use 12 gauge wire for your expansion. If it's a 15, use 14 gauge wire.

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Many of your suggestions make sense, but this questioner is so inexperienced that any handling of wiring or fixtures is very risky. Even a look inside the panel box requires removal of the cover. Sharon needs a pro. A DIY project needs either a low risk task or at least some familiarity with the field. As is said in the medical field, when picking up a scalpel, you need to at least watch one before you do one. –  bib Feb 5 '13 at 16:44
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