On our tour of the electrical system, we start with the wires bringing the power to the house. These wires can be underground or overhead, and up to the point that they enter the meter (or a splice before the meter), they are the responsibility of the utility provider. Visually there is not much to see with the underground cables, so we will look at overhead wires. The wires are called the service drop when overhead (and the service lateral when underground). The wires should appear in good condition, and they should not be in an area where they can be damaged by a tree or touched by you. There are codes regulating where these cables can go, but without being to precise, you want to see that the wires are free and clear of all obstructions (like doors or tree branches) and not too close to where some one can reach out to touch them (like close to the ground or near a window). Fraying wires are a hazard, so they will need to be taken care of. Next look at how the cables are secured to the home. The cables should have a drip loop (a place where water will drip down, instead of flowing along the wire to the house). The masthead is the tube coming off of the roof to and service panel bring the wires down to the meter. This tube should be secured to the house, and it should be in good condition.
Now we come to the service panel box. This can be in the house or outside. In some homes, builders would place these panels in a closet which is a bad idea. There is a possibility of fires being caused by this spot. Let me say this once, so I will not keep repeating this fact: any piece of equipment (be it an outlet, panel, light fixture, or whatever) or wiring for the electrical system needs to be firmly secured to the structure of the house to prevent damage to the wiring, which could cause a fire. I did not want to be repeating the “secured” phrase each time, so be on the look out for this situation on each piece of equipment. Most securing issues may be tightening a screw for an outlet or redoing a screw with a clamp. The service panel box should not be rusted. Open the cover, and check for labels telling you what the breakers (switch like items) control.
Before we go further, I have a warning: do a visual inspection only, because it will be real easy to electrocute yourself when investigating the electrical system, so do not pull on wires or poke your fingers about thinking it will be safe. There should be one breaker to turn off all the power to the house, or you should be able to shut off all the breakers with six swipes of your open hand, so if you see a long row of breakers and a subpanel with no main breaker, you have a problem. There should be no empty slots. You will either have a circuit breaker or a cover plate for each location. Check to see if a breaker has tripped- it will feel loose, as if it is between being on and off. A tripped breaker could mean a bad breaker or not enough amperage to serve that circuit. To remove the panel covering the wiring, place the back of your hand on the cover. If it is hot or has a current, your natural reaction will be to pull your hand away (when you use the back of your hand; using your palm will cause the reaction of grabbing the panel). A hot panel indicates a problem inside, so now you would need to proceed at your own risk. If you feel comfortable, remove this panel. You will now be looking at a mess of wires. The wires should look in good shape. Melted or frayed wires mean issues. Each circuit breaker will have only one wire coming into it (these wires will be black). The interior should be free of debris. Nothing should be loose in here. Black wires are hot, white are neutral, and grounds are usually bare copper. About ground wires, Americans use green to indicate ground, while Europeans use brown. I mention this, because I have seen do-it-yourself projects with brown wires used for grounds, so obviously it was wired by someone familiar with that standard. Ground wires were not installed in homes till the late 1950s, so an old home may not have a grounding system.
For a proper check, you will need an electrician beyond this point, so replace the cover. You may want to make note of the amperages, particularly for the HVAC system. On the condenser (compressor) unit, look for the maximum amperage on the tag. This will be the amperage needed for start-up, and there should be a breaker with that amperage. Sometimes an older HVAC system is replaced by a newer one during a home sale, but the installer did not happen to upgrade the breaker, so the system will not work. This only happens with a company that does not do a good job.
Lastly for the panel, look to see that it has a clear space all round it for a worker. If there is a subpanel, go through the same procedure. If any panel has FPE or Federal Pacific marked on it, run away screaming with your hands flailing in the air. Seriously, these are dangerous panel boxes, so do not inspect them, unless you really know what you are doing. These were installed on homes in the sixties and early seventies by builders, since they were inexpensive.
Last stop before going inside, you will be looking for a grounding electrode. Up to the 1980s, water pipes could be used to ground the system, but then every one had to use a rod of either ½ or 5/8 inch diameter. This rod is the grounding electrode. Generally a 6AWG bare wire from the panel would attach to this rod. The rod itself goes into the ground for eight feet. I frequently see people run lawn mowers over this rod, damaging the wire or the connection, or I see rods rusted so that the top is detached from the rest of the rod.
Moving into the interior, you will have one problem checking out the branch circuits- equipment. My assumption is that you are walking through a house to judge how much work it will need, so I am writing this with the idea that you have no tools, except maybe a tape measure and a screw driver. An inspector has a circuit tester as his main tool for checking outlets, among other tools for checking the current. Most other tools may be a higher cost, and if you are going to use an inspector, let them handle a more detailed investigation. A circuit tester may not be a bad investment, and it is not expensive. When plugged into an outlet, this device can check the current and GFCI.
Sticking to the visual side of the inspection, turn on any item operated by electricity to see if it works, but note that some lights may be a burned out bulb, and not a fixture problem. If an owner or tenant is around, I might ask them. Tenants have always been forthcoming with information. Remember to check for secure fixtures and outlets.
You may come across a switch that does not seem to belong, so here are some ideas. If the switch is along the kitchen counter, it may operate the dishwasher. This was done by some builders as a safety measure for working on those units. If it is in a bedroom or den, and there is no ceiling fan at the light fixture, the builder may have run wires for the fan, which he thought you might want to install. In those places, the switch may be for controlling an outlet, so a lamp can be placed there for light. This is usually done in rooms without overhead lights. Generally, the builder will let you know which outlet is being controlled by turning it upside down, but this is not always the case.
If you do have the proper screwdriver, remove an outlet cover to check the wiring. The wiring type can be seen by looking at the ends where it will connect to the receptacle. More than likely, your service wires at the panel will be aluminum, and the wires for the branches will be copper. If this is the case the wires at the outlet will be copper as well. If the branch circuits have copper and aluminum wires, look for a marking that says CO/AR (pronounced like “co-lar”) on the receptacle. When checking outlets and switches, ensure they have complete covers. Wire connections should always be in covered junction boxes, and the connections should not be tape. You need to see a wire nut or some other connection means. Copper and aluminum wires can only be connected with a wire nut which is purple in color. The color is a code to indicate that it is a special connector that can handle this type of union. Extension cords used as cabling for outlets or fixtures is not allowed. Lastly, we end our tour with GFCI (Ground Fault Circuit Interrupters) outlets. These are outlets with a test button on them (some circuit breakers have these too), but every outlet on this circuit has to be marked with a label stating “GFCI”. Usually one outlet will control several down the line. These outlets are needed in any area that can become wet: kitchen; garage; bathroom; exterior; or wet bar. The exception to this rule is the refrigerator outlet in the kitchen and outlets in the soffit on the exterior. You do not want the refrigerator going off when the circuit trips, and someone fails to reset it. The soffit is high enough up that now water will get into the outlet.