Wiring Your New House Part 4 – Installing Your Electrical Service
March 8, 2007
In part 2 of this series, I showed you how to calculate what size electrical service you need. The calculation for this hypothetical house came up to be the 100 amps minimum. However, I highly recommend installing 200 amps. Two Hundred amps is going to allow for future growth and add resale value to your house.
I am going to assume this house is in a new subdivision where the utility company’s power is underground. I am also going to assume that you have an electrical permit and local code requires a disconnecting means on the outside of your house.
So, let’s get started. The first step is to mount the 200 amp meter main to the outside of the house. This needs to be mounted 3′ away from any window and between 5′ to 6′ above grade to the center of the meter. It is best to coordinate the location with your local utility company. They will typically connect to it wherever you mount it. However, if the utility company’s transformer is nearest to the left front of your house and you decide to mount your meter main to the right rear, it will probably cost you more money.
Now before you mount the meter main, there is a little prep work involved. There are concentric knockouts on the bottom, sides and back of the meter main. On the meter or utility side, you need to remove the knockouts up to 2″ on the bottom. On the main breaker side, you need to remove the knockouts up to 2″ on the back.
Next you need to drill a 3″ hole through the siding of your house. This hole is for the cable that will come out of the back of your meter main and feed the breaker box or load center. Next you install a 2″ SER connector and plastic bushing in the 2″ hole you knocked out of the main breaker side.
The easiest way that I have found to mount this meter main by yourself is to temporarily fasten a 12″ piece of 2×4 where the bottom of the meter main will be. Then just set the meter main on top of this 2×4 and screw it to the wall. Then remove the temporary 2×4.
Now let’s mount your 200 amp main lug breaker box. We typically mount these in the basement, in a utility room, in a mechanical room or in the garage.
Now you may install the 4/0 SER cable between the meter main and breaker box. Install another 2″ SER connector and plastic bushing in the top center of your breaker box. When terminating the wires in your breaker box, be sure the grounds and neutrals are separated. Sometimes there is a green screw that bonds the neutral bar to the breaker box’s frame and sometimes there is a bonding strap. Do not install these in your breaker box.
Aluminum wire will oxidize very quickly. So, you need to place a little de-ox on the ends of the aluminum wires before terminating them. When terminating the wires outside in the meter main, the grounds and neutrals connect to the same neutral/ground bar.
Finally, you need to ground the system. For this you need to run a # 4 copper ground wire either to within 5′ of the water meter or to a concrete encased electrode. If you connect to your water line, this must be a metallic pipe extending atleast 10′ outside of your house.
When connecting to your water line, I recommend connecting to the street side of the meter and with a continuous loop connect to the other side of the meter as well. The reason for this is most water meters have either rubber or neoprene bushings that break the continuity of the water line on each side of the water meter.
You also need to install an 8′ ground rod right near the electrical service and run a # 6 copper ground wire to it.
Now call the electrical inspector and get this inspected and call the utility company and get your power turned on.
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