Author’s Note: I am better at explaining building concepts verbally to clients during a home inspection than I am at writing about them (or at writing in general). I also feel that construction concepts can be learned by anybody and understanding them will help homebuyers make more informed decisions when buying their homes. The hope is that these articles will culminate into a book that is approachable and has valuable information to the consumer. I am also publishing these articles on my blog for feedback on how this article can be better. Please comment on my grammar or how I write. You are my editor.
Electrical Explained
By Jay Marlette
The Conceptual Electrical System
The problem with discussing how electrical systems work in a house, one needs to discuss Watts, Amps, and Voltage. These are nice concepts to understand but besides sizing how much service a building utilizes, several common defects discovered during a home inspection have very little to do with calculating wattage.
A Brief Explanation of Watts, Volts, and Amps
Let us start with the water analogy for electricity. Water goes down a pipe like electrons go down a wire. Both substances provide an ability to do work. Water coming out of the end of the pipe can turn a paddled wheel but probably not fast enough to get the blender to work very well and waterpower alone is difficult to use when making toast. So we turn to the power of electricity to do work. Each electrical appliance requires a certain amount of power measured in watts. Watts is a multiplication of amps and volts. What are amps and volts? Think of volts as the water pressure and amps as the water flow. So even if there is a lot of water pressure from the water source (Volts) you are only going to get so much water flow (Amps) out of your end of the pipe depending on the size of pipe. Just like water pipe sizing, you only get so many amps that can pass through a wire depending on the wire’s size and appliance load.
How Electricity is Used in a House
Power comes from the utility company and into a transformer. From the transformer power goes to the house. The wire or wires that bring power to the building are the “Hot” wires. Those electrons don’t stay in the building. Once the power is used, the electricity then goes through another wire from the house and back to the transformer. That wire is the “Neutral Wire”. From time to time you will hear about a ground wire. On three prong plug receptacles, this ground wire is connected to the lower third prong. This is a wire that hopefully leads an inactive life. This wire is there so if electrons escape from the house-to-utility company loop it will have some place to go. Maverick electrons are simply trying to return to the earth. If we provide a more direct path to the earth perhaps people and electrical equipment will not get caught in the maverick electron stampede. Grounding the electrical system to the earth and grounding metal plumbing that could possibly be charged to the earth provides a degree of safety but also provides a path to the earth if the building is struck by lightning. Grounding also reduces noise on communication equipment.

Making Power Safe
Different types of appliances and fixtures require different loads. A load is the electrical demand of a piece of electrical equipment measured in amps and watts.

The way building electrical service works is power comes into the building (those overhead lines are the hots and neutrals). The power first goes through a meter so the utility companies know what to charge you, Those power lines are then connected to a breaker box that is attached to the house. Next, circuit breakers are plugged into this box. The breakers have switches on them and the ends of the switches have a number that represent how many amps may be ran through that circuit. Each breaker is like a thermometer that turns itself off if the circuit wire connected to it gets too hot. The breaker shuts down when the amount of heat passing through that breaker exceeds what is normal for that sized breaker. For example; a fifteen amp breaker (15 is the number at the end of the switch) will allow only enough power (or heat) to pass through it to allow for approximately fifteen amps worth of power. If significantly more heat than fifteen amps worth passes though the breaker, it will shut off. Fuses work the same way but instead of turning off, they burn out and need to be replaced like a light bulb.
Wiring sizing is important. The wires are sized by how much load we intend to pass through them. If we want to power lights we will install a 14 gauge wire in a 15 amp breaker to power the lights. 14 gauge wires are the thinnest wires we generally use in a building and they tend to serve smaller loads. If we want to power larger loads, like a dishwasher, we will use a 12 gauge wire on a 20 amp breaker. Wire gauge is a little confusing. The larger the number on the gauge rating, the smaller the wire.
Explaining 240 Volt Power
The concept of electricity does get a little confusing when discussing 240volt power. It is simple when explained. Remember those overhead wires entering the building? There are three. There are two hots with 120volts each and one neutral. One may ask, “…if we have two hots and we know the power returns to the transformer through the neutral wire, why don’t we have two neutral wires?” The answer is the two hots share the neutral wire when electrons return to the utility company. Then one may ask”…won’t the neutral wire burn up when both hots return the electricity through the one neutral wire?” The answer is yes if we were dealing with direct current but we are dealing with alternate current. Those two hots alternate when they pulse power to the building. In other words, those hots never constantly flow power into the building at the same time. At very high speed they dose the building with power in an on/off manner and never at the exact same moment. So the neutral wire that returns power to the utility company never gets a dose of power more than 120 volts at any one time. So one may ask, why do we have 240 volt power? Why don’t we just have 120 volt power? Well, we use to but now with electric stoves, electric water heaters, and electric dryers, the power could not get to the appliances fast enough to provide the heat energy necessary for these appliances to work.

Electrical Defects
Electrical defects can be found all over the building. This is why categorizing electrical defects can be difficult. Since this book is intentionally over-simplifying the house for an improved overall understanding of systems, we will give the electrical defects three categories; panel defects, circuit branch wiring defects, and those defects around fixtures, receptacles, and junction boxes. Defects described here will be those most common found in the author’s home inspection experience.
Panel Defects
Panel defects are found when the home inspector takes the panel cover off for a closer look. These defects include breaker configurations, wire sizing, labeling, wire connections, and grounding configuration. There are some breaker manufacturers with a bad reputation for not shutting down in time to prevent a building fire.
Starting with breaker issues, one of the most common defects found, even in brand new construction where permits were finalized, are multi-branch wiring defects. At this point, please keep in mind that even though permits were finalized, serious defects could exist. A professional home inspector, as opposed to a city inspector, not only has the luxury of time needed to thoroughly inspect a building, they also carry a lot more liability and tend to be more careful (This is an oversimplified statement. Let me mention here that among the building inspector crowd, I have met many dedicated inspectors who fight an uphill battle to improve building standards and their enforcement). A multi-branch defect is when a neutral wire is shared between two hots in an unsafe manner. Remember how we discussed how the main service wire (the wire you may see hanging over the street and connecting to the building) has two hots and one neutral? Sometimes to reduce the amount of wire installed throughout a building, two hot wires will share a neutral wire. This is commonly done when there is one breaker serving a dishwasher and another is serving a disposer. Since both appliances tend to be plugged into the same location, under the kitchen sink, then it makes since to have both those circuits share the same neutral wire. If one breaker is plugged into the breaker panel that is associated with a 120volt service wire, and the other breaker is plugged into the breaker panel at a point associated with the other 120volt service line, then the power alternates and the neutral wire shared never gets more than 120volts passing through it at a single moment and is safe. However, if the electrician goofs, and places both breakers on the part of the panel associated with the same 120volt service line (commonly referred to being on the same pole), then the neutral wire takes on too much power and can pose a building fire hazard. This is often corrected by reconfiguring the breakers in the panel so the neutral safely shared.

Another breaker defect is “Double Lugging”. This is when more than one wire is attached to a breaker. Some breakers are designed for this application but in most case double lugging creates an insufficient connection to the buildings circuitry and indicates insufficient breakers to service the building. The worst case scenario, double lugging could case an arc resulting in a fire.
Count wire-to-breaker connections from the top. The fifth connection from the top, two wires are inserted into the breaker. This is double lugging.

Some breakers need to be bridged or linked. When two 120volt wires are used on one appliance like an electric stove or dryer or when two circuits (a breaker and wire) enter the same junction box (like the junction box where the dishwasher and disposer plugs into) a bridge or link is required. A bridge or link simply forces two breakers that serve the same receptacle to go on or off at the same time. Here is the logic. An electric dryer is served by two 30amp breakers. Suppose one wants to change the plug receptacle serving the dryer to a more modern type. If one turns off the one 30amp breaker and the other does not shut off along with it, then the service provider will get shocked when he or she opens the junction box where the receptacle is replaced. The service provider falsely believes the power is out but there is a live wire from the other pole that was did not shut down.
The manufacturer of breaker could have an adverse effect on the building’s safety. Some breaker manufacturers are known to be prone to failure. Failure basically means that the breaker fails to shut down before the building catches on fire. The easiest manufacturer to pick on is the Federal Pacific Electric breaker. The Consumer Product Safety Commission published studies that support the idea that all Federal Pacific Panels should simply be replaced. Testing has supported that Federal Pacific Panels, especially the two pole breakers (240volt breakers) have a higher than average failure rate in terms of shutting down before a fire could occur. This study was conducted in 1982 in accordance to the Underwriter’s Laboratory standard 489. Some electricians serving FPE panels do not know that certain Federal Pacific Breakers do not fit in some FPE panels, one could inadvertently force a Federal Pacific breaker into a panel in a way that could cause a fire hazard without realizing it. The “Stab lok” Federal Pacific breaker design does not establish a solid connection in the panel as well as a modern panel. This could result in arcing and a fire hazard. Other manufacturers like Zinsco (also known as Sylvania because Sylvania bought Zinsco in the 1970s) and Bulldog’s Push-o-Matic have more field reports indicating that they may be defective but not as conclusively as Federal Pacific Electric. Most of these suspect panels were manufactured between the mid 1950s to the mid 1980s. That means regardless of the manufacturer, we are dealing with panels that are in excess of 20 years old. Breaker plasticides, springs, and other components have worn out. Breaker safety requirements have improved since these were manufactured, and these panels have been exposed to decades of environmental exposure. Simply due to old age, consideration should be made towards upgrading the panel.


To Be Continued … We will continue to discuss defects in the branch circuitry (House Wiring) and defects in junction boxes, receptacles, and so on.













