Go to How Not to Build an Addition Index! This page includes notes on fuse boxes.


After the power meter, your wires are directed, by conduit, to your main power distribution panel (also called a fuse box). This is where all of that surging raw power is diverted to various locations in your house. Your main cables usually run through a main circuit breaker and then via bus (in rare cases a taxi) to individual circuit breakers or fuses that guard the flow of electricity to various locations. In the event of a heavy power draw or power surge, the power connection will be broken. If this happens frequently, it usually means that you have a short in the system. In the case of a circuit breaker you have to either live with the problem and keep switching on the broken circuit or trace the problem to its source. In most cases, it is easier to just live with it.

The other important thing to note about the circuit breaker panel is the labels on the door. In the course of construction on my addition, I found it necessary to pull the door off the circuit panel. Misplacing this item subsequently created some confusion.

One day I had to replace a fan in a bathroom in the old part of the house. Because of the lack of labels, I had to check out several circuits before I found the one I intended to work on. One of the circuits I tested seemed entirely useless. I could find no lights or appliances in the house to which it was connected. So I turned it off along with the one I needed to douse in order to work on the fan.

The bad thing about bathroom fans is that to get to them you have to climb into the attic. This can be a major operation. Despite the summer heat, I put on a long-sleeved shirt, a ball cap, gloves and long pants to protect my body from the floating fiberglass insulation. I was encumbered with a hammer, a screwdriver, pliers and a flashlight. I crawled as if I were a commando, up a ladder, through a narrow hole, into the furnace-like attic, over the ceiling joists and under the low hanging rafter beams. Carrying a flashlight in my teeth, I slithered from beam to beam. I realized that, with one false move, I could slide off the narrow beams and put all my weight on a piece of drywall. Such a move could send me crashing through the ceiling below.

Naturally, the strain of this balancing act, combined with the accumulated heat of the attic, exacerbated by the layer of clothes covering my body made me very uncomfortable. However, being a man, I persevered.

When I reached the appointed location, I readied my tools. I was about to jerk out the old fan box, when suddenly my flashlight dimmed. "Darn, I thought, now I need new batteries." Robin was not at home, so I had to crawl back to the attic access and down the ladder to find more batteries. Unfortunately, no batteries were to be had, and I was forced to deal with a flashlight that only worked for about thirty seconds every time I pounded its base against a two-by-ten. Back in the attic, I set to work. It was not long before I realized that I needed electrical tape. After having to make two more sallies to the fan's location (the last trip because I needed a ground screw), I finally got the fan hooked up to test. I crawled wearily out of the attic and trudged all the way to the fuse box, then back to the fan. I looked up at the 50 cfm piece of junk and found that it worked only when I pushed on the fan box.

A brief obscenity passed my lips, and I climbed back into the attic to see if I could identify the exact problem. I crawled toward the fan. Sweat was dripping from my forehead in huge beads. Meanwhile, I intermittently banged the end of the flashlight and dragged my tools over the pickery fiberglass insulation. When I got to the fan, I immediately identified the problem: a wire I had not connected quite tightly enough.

You may imagine my thought process at this point. I could again crawl thirty feet over evenly-spaced two-by-tens that were standing on end, climb down the ladder and shut off the power, then climb the ladder, come back to the fan and complete the job, OR...OR I could take care of the entire matter right here and now. For me, the choice was easy; I applied my insulated pliers to the live wire. It was not a smart move but a theoretically efficient one, unless you take into account the intermittent flashlight going dark at the wrong moment and the wire twisting loose from the pliers and an exposed bit of skin between my glove and my long sleeve shirt.

I am now certain that sweat is a great conductor of electricity because I felt the shock of the experience throughout my entire body. Needless to say, in the end, I made another trip to the circuit panel and sweated out another climb.

Another trip to the circuit box and back to the bathroom found the ceiling apparatus working well. Still somewhat dazed with the electric shock, I went back to the panel. I decided to leave off the unconfirmed circuit I had found earlier. I had already been shocked once that day; it made sense that I did not want electricity wandering through unexpected corners of my house.

Drenched with sweat and wishing to shed the 900 degree heat, I tromped into the garage. Reaching into the big freezer, I pulled out a popsicle and took a well-deserved break. I did not think much about it at the time, but I noticed that the light in the freezer had blown. Not a big deal, we did not often get out to the garage freezer in the middle of the night.

Five days later a light came on in my own brain when I realized that the light in the freezer might not be blown and the unidentified circuit might be performing a necessary function. I ran to the freezer as if a few seconds would make a difference in a thawing process carried on over several days. To my chagrin, I was forced to dispose of a side of beef, one-half gallon of ice cream, two well-aged filleted salmon, and a lifetime supply of melted sticky popsicles.

110, 120, 240, HUT, HUT, HIKE

Voltage is the amount of raw power that is coursing through your wiring. 110 and 120 are basically the same thing only there usually is no ground wire with 110. 240 is two wires carrying 120 volts in the same wrapper. Most of your appliances will run very well on 110 or 120, but some, especially the big monsters that do a lot of heating, require 240. Your electric stove and dryer are good examples. I have fondly imagined that for really big jobs you might need 360 or even 480. These voltages, I presume, can be achieved by grouping several wires together and might power such appliances as a very high speed power drill or your teen's stereo system.

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Fuse Box
Three Way Switch

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About the Author:
W.J. Rayment built an addition on his house, and in the course of the project learned from his many mistakes. This on-line compendium is his effort to help you learn from his experience. The advice and stories are often humorous, sometimes silly, but always informative. for yourself or as a gift for family or friends.

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