Inspecting Home Electricity (part 1)
This article is meant for reading and helping you understand some of the issues home inspectors look for when inspecting an electrical system of a property. I strongly recommend having a licensed professional evaluate your home’s electricity, if you are experiencing problems.
When evaluating a home’s electric from the outside, we generally start examining the wires coming from the utility pole to the point of connection to the house. These are referred to as overhead services. Electrical wires can also run underground to a property in a pipe, the services mass, which connects to the meter and then enters in the home’s electrical panel.
The services mass should be well secured to the property, in some cases the mass is penetrating through the roof. A drip loop is required on all wires entering the services mass, as this helps prevent water from entering inside.
The height standards in the U.S. for wires over a property varies depending on the location of service drop. See Illustration
Electrical panels are boxes that house circuit breakers and/or fuses, which are safety devices that stop the electrical current if it exceeds the safe level of the home electrical system.
• 80% of the time “Insufficient Clearance” is a deficiency inspectors catch. According to the 2008 National Electrical Code, most residential electrical panels require at least a 3-foot clearance or working space in front, 30 inches of width, and a minimum headroom clearance of 6 feet, or the height of the equipment.
• CORROSION; Corrosion is perhaps the most common problem I see and it ranges from very slight to excessive. Any source of moisture, be it humidity, a dripping faucet or water entering a frayed main service wire, can do serious damage to electric panels. Eliminate all sources of moisture, even general interior humidity, as these will likely lead to corrosion inside the panel. Only slight corrosion may not warrant any action. However, once corrosion gets bad enough, connections become compromised and repairs/replacements must occur.
• BAD PANEL; Sometimes it’s not the particulars inside the panel that are problematic; it’s the panel itself! Such is the case with Federal Pacific “Stab-Lok” panels, Zinsco panels and a host of older outdated panel types like fuse panels or early style breaker panels with limited circuits. Both the Federal Pacific and Zinsco panels have histories of breaker failures, although with slightly different aspects. In both cases, the way the breakers work (which is to provide over-current protection) was poorly designed and could lead to failures and fires. With older outdated panels, the problem is more about space than it is about over-current safety. Plainly stated, older fuse panels and some breaker panels (like the Pushmatic panels) just don’t have enough room to handle the electrical needs for today’s homeowner. In all of these cases, some form of evaluation by a licensed electrician would be in order. These photos, in order, are an old fuse panel, a Federal Pacific panel and a Zinsco panel.
• OPEN KNOCK-OUTS/NO CLAMPS; This is another common deficiency. A panel enclosure is designed with multiple wire or breaker “knock-outs” (sometimes called “twist-outs”) that allow the installer to make an access point for wires and breakers. Many times, however, these knock-outs are removed and nothing is put in their place, leaving gaps in the electric panel enclosure. These gaps, especially at the front cover where the breakers reside, can be dangerous as they allow access into the enclosure. Similarly, I also see wires running through these openings that do not have the proper clamps in place to keep the wires from moving around and getting damaged. Adding covers and strain relief clamps can be a relatively simple fix to these problems.
•“DOUBLE TAPS;” The terms “double tap” and “double lugging” refer to when multiple hot or neutral wires are physically connected to a single lug (on a breaker or a bar) where only one wire should be connected. This is most common on breakers and is usually done because there are no more slots in the panel to add new circuits. So, the only other option is to “tap” into an existing circuit at the breaker’s connection (lug). While not normally a serious concern, double tapping is contrary to proper installation practice. If a panel has double tapped wires at the breakers, chances are the need for circuits has outgrown the capabilities of the old panel and a newer, larger panel upgrade is in order. In some cases, adding a subpanel may be a better option.
• OVERSIZED BREAKERS OR FUSES; Sometimes this problem is called “over fusing”, although the term is used for any form of wire/over-current protection mismatch, be they breakers or fuses. This condition occurs whenever a load-carrying wire is undersized when compared to the amperage rating of the fuse or breaker to which it is connected. Here’s an example. Let’s assume a 14 AWG copper wire (the smallest wire used for residential electrical wiring) is mated to a 20-amp breaker for a kitchen where dishwashers, disposals and other appliances routinely draw a fair amount of power. That small 14 AWG wire is not large enough to safely carry a load of more than 15 amps. However, if a load of 18 amps is running across that wire (common for certain devices or appliances), the circuit’s 20-amp breaker won’t trip! The circuit’s over-current protection (the 20 amp breaker) is designed to trip at or near 20 amps of current. But by the time our 18 amps of current are traveling on that 14 AWG wire, it may be too late. The wire could overheat and melt the outer wire jacket and could even lead to a fire. If that 14 AWG wire was properly mated to a 15 amp breaker, it would have safely tripped to the off position at or near 15 amps, never getting to the 18 amps in our example. Conversely, if the 20-amp breaker is retained and the wiring is increased in size to 12 AWG, the thicker wire should allow for an 18-amp current with no problem. This over fusing condition can be very serious and has the potential to burn down a house! Despite the gravity of the problem, it is one that I see quite often.