Electricity can be dangerous.
You should always turn the circuit off at the breaker box or remove any fuse to a circuit you are working on.
One easy way to find the circuit is to plug-in a radio in to the branch you want to work on then turn off breakers at the main box until the noise stops. Once the circuit is cold you want to tape that circuit breaker in the off position and hang a sign over it saying its under repair and not to touch. before you do any work you must check the box or circuit with a voltage tester because you never know your radio may have just died and the line may still be hot.
When you order Electric Service for your New Home the electric company will provide what is called a Drop. This is the line that comes from the pole or underground to your house. The cost is usually about $1500 but can be more or less depending on your area.
Once the line is to your house (actually they won’t install the drop until your service line and meter and breaker box is up) you will need to install Service Line and a Meter Box. Service Line is the thick wire that runs from the Meter up the side of most homes to the Drop Line.
The Electric Company will provide the Meter and you will install another piece of Service Line from the Meter to your Circuit Breaker. Although not required older homes that have Fuse Boxes should really be upgraded to Circuit Breaker Boxes.
Circuit Breaker Boxes
are the branching point for all of the individual circuits in your home. Breaker Boxes are rated in AMPS. Normal circuits in your house will run on a 15AMP breaker. Where more power is needed a larger Circuit breaker is installed like a 30AMP breaker for your furnace or a 20AMP breaker for your stove or electric dryer. All of the Circuits in your house must add up to the Rating of the Circuit Breaker Box. If you plan on installing Heavy Tools in your Garage or Powering an Out Building like a detached garage get a larger breaker box do not just install higher rated circuit breakers.
Circuits in your house are separate runs of wire that power a portion of your appliances. In best practice each main room should have 2 circuits and the circuits can be shared between rooms. This is to allow power to the room if one circuit may fail.
Dedicated Lines / Home Runs
Some Appliances must have their own private circuit. Alarm Systems, Furnaces, Air Conditioners, Large Kitchen appliances like your stove and your computer should all have their own line. This is so that someone running the blender in the kitchen doesn’t shutdown your fire alarm when the circuit breaker jumps.
A few appliances may require Hardwiring of their circuit. This is where there isn’t a box on the wall and the wire goes directly into the appliance. Furnaces are one appliance that require a Hardwired connection.
As said above most of your home will be using a 15amp circuit.
15amp Circuits require 14 Gauge wire normally called 14-2. This is where there is 1 hot, 1 Ground, 1 Neutral wire in the wire set.
20amp Circuits require a heavier 12 Guage wire
and 30amp Circuits require 10 Gauge wire.
All Modern Wiring is Shielded. If your home is extremely old and the owners never upgraded the wire you could have unshielded wire running on insulated blocks. This is EXTREMLY DANGERIOUS and you should upgrade the wire in the house immediately. Unshielded wire can result in fire and electrocution.
All Splices or connections must occur inside a box. This means that ALL CONNECTIONS MUST OCCURE INSIDE A BOX. You can not just tap into a circuit and use wire nuts and electrical tape. Also electrical tape should never be used on home wiring.
All wiring outside the home such as a run to your detached garage or lights at the bottom of your driveway must use waterproof wire. This is called underground feeder line. You should not locate regular inside rated wire that is going to be outside under ground in a conduit pipe.
Running inside wires
All wires should be run inside a wall space but when that is not possible the wire should be protected. In unfinished basements you can use a metal conduit and a metal receptacle box.
When running wire in a wall space you must staple the wire so that friction will not cause failure of the shielding. Normally you will use a staple not less then 6″ from a receptacle where possible. You should also staple the wire often enough (aprox every 2 feet) that it will not move within the wall cavity.
Wire should be located in the center of the width of studs and joists not the edges where a missed nail could hit it. When running wire through a stud or joist you must take care to only make the smallest hole possible and also place the hole in the center of the width to avoid nails. Too large a hole in a joist or stud will degrade the strength of the wood. One Half Inch is the largest hole that should be placed in a 2×4 stud.
Receptacle Outlet Boxes
Most new boxes are plastic but some are still metal. The choice you make will be related to the placement of the box. Inside the wall boxes can be plastic and will reduce the chance of shorts. Exposed boxes such as in your unfinished basement or outside your home should be Metal. Boxes and other electrical equipment outside the home MUST also be rated for outside use.
Some outlet boxes are for special use such as a Ceiling Fan Box. Take special care to install those boxes as recommended.
The number and locations of outlet, switch and dedicated light boxes is set in the Electrical Building Code. In General the distances between Outlet Boxes must be close enough that any appliance can be powered with a 6ft extension cord. Boxes for Lights must be located in stairways and bedrooms. Switches must be at a set height above the floor to allow easy access.
The Electrical Code
National Electrical Codes have been recognized in almost every location in the USA. The reason for this is basic safety. Following the codes should not be thought of as a problem it should be thought of as the very base minimum that you should do to stay alive. Believe me the codes are not set too high and more often then not you will want to do a better job then just the minimum. Look at it this way you paid $2000 for special tires and wheels on your car when you could have had the factory steel wheels but you don’t want to spend an extra 49 cents to be safe in your home.
As always if you do not feel you can perform this work by yourself then hire a professional. Some areas may require all work to be done by a licensed electrician. Others allow home owners to perform the work. Check with your local Building Official or you could have problems with your Insurance.