While helping a friend with some routine maintenance on their home I came across a very shocking discovery! It appears that the appliance installers for his electric stove apparently did not know how to properly install them. Read on for more information that could potentially save your life!
In a previous post ( Why are two prong outlets written up as unsafe by the Inspector? ) I discussed the importance of the third conductor (prong) on the three prong outlets. The purpose of that post was as a lead in to this post as both are extremely important to the safety of you and your family. I will not repeat the entire contents here, and ask that you visit that post for a more in depth description on the use of the Equipment Grounding Conductor (EGC) or third prong on an electrical outlet. This post is about the use of that third wire (the EGC) as it relates to your electrical appliances.
If a fault occurs that is severe enough it can potentially energize the the metallic parts of your appliances. It is important to note that the EGC is a safety feature used to drain off any electrical current on the exposed metallic parts of electrical appliances (the parts we humans can touch) when a fault occurs with the appliance. The EGC wire, and the exposed metallic parts, should never have any electrical current flowing on them in normal operation.
In the previous article mentioned above a typical 3 prong, 120 Volt, wall outlet was discussed. Your appliances that function off of 120 Volts Alternating Current (VAC) will use the previously described plug an outlet. However larger appliances such as kitchen stoves, clothes dryers, etc., have larger voltage and current needs. These appliances will typically operate off of dedicated 240 VAC electrical cable runs from your breaker panel. Picture 1 displays a typical 240 VAC appliance plug. Along with 240 VAC your appliance might also require 120 VAC for lower voltage needs. The purpose of each prong are:
- Prong 1 is the safety EGC connection.
- Prong 2 is the neutral connection.
- Prongs 3 and 4 each provide 120 VAC connections to the electrical system.
To obtain the 120 VAC for lower voltage requires a connection inside the appliance is made between prong 2 and one of either prong 3 or prong 4. To obtain the 240 VAC voltages a connection is made between prongs 3 and 4. Prong 1 is always attached to the exterior metallic cabinet.
Picture 2 displays a typical 240 VAC outlet for use by the plug just described. The plug and outlet displayed here are for an electric range that was being moved out of the way during this routine maintenance.
From this little bit of viewing it would appear that this electric range was installed with the newer 4 prong, 240 VAC plug and outlet, with the safety EGC connection. The maintenance being performed was not with the range or electrical system so what tipped me off to a potential problem and why I should dig further. Read on and learn more on safety!
[tab: The Issues]
The first sign of an improper installation was evident when we first pulled the electric range out from its location between cabinets. Picture 3 displays the power cord was not even properly secured to the range. The black outer jacket of the 240 VAC cable should be extending through the metal plate and secured in place by the strain relieve assembly. The metal mounting plate on the rear has sharp edges and the strain relief clamp provides a smoother surface for the protection of the cable. In this installation the individual wires inside the cable jacket were being sliced and damaged by the sharp edges of the mounting plate.
The homeowners had been pulling this range out at least once a month to clean it, and behind it, never realizing the danger they were in. Had that metal plate sliced all the way through one of the 120 VAC wires it could have shorted to the case of the range and provided a lethal shock to anyone touching it. At this point there was no doubt that the protective cover on the rear of the range needed to be removed to check for a proper wiring installation.
Picture 4 shows the connections of that 240 VAC cord to the rear of the range after the protective cover was removed. It also displays how the individual wires were running through the sharp edged opening of the mounting plate. Here we see the deadly error that this appliance installer made! The green EGC wire was directly connected to the white neutral wire. The copper bonding strap was left in place (from the manufacturer) and connected to the range’s cabinet. The red and black wires are the individual 120 VAC feeds described previously. The appliance installer never bothered to properly modify this arrangement for the available EGC safety connection.
In older homes without the safety EGC wire available the practice was to connect the neutral connection from the breaker panel directly to the equipments cabinet. This was the original method of providing a safety equipment ground. Unfortunately this arrangement could cause other problems, and safety issues, of its own. Since then the EGC has been added as a separate run and essentially isolated from the neutral and hot connection(s).
Appliances manufacturers do not know how your electrical system is installed and will leave that copper bonding strap in as shown here. In this way the appliance installer has it available if you have an older wiring system. The manufacturer also generally does not have a power cord attached to the appliance when it is delivered. This forces the appliance installer to open that access cover and properly install the cord and remove that bonding strap if it is a newer electrical system installation.
This home is a newer home with a properly configured electrical system. Prior to changing any of the appliance connections this was easily verified. Picture 4 displays how that electric range should have had its power cord properly installed. Note the cable now has its outer black jacket extending into the terminal strip area and is properly secured by the strain relief assembly. Also the copper bonding strap has been removed and the power cords EGC wire has been directly connected to the ranges cabinet connection point used for that purpose. The EGC connection on appliances is typically designated with the green colored screw and/or terminal point as shown here.
All of the appliances in this home were purchased from the same very large store. All of the appliances were delivered and installed by the same store, on the same day. All of the appliances were checked and the clothes dryer was also improperly installed by supposedly licensed appliance installers. I really was flabbergasted that this occurred as the appliance field is a licensed trade. Read on to see what you can do to prevent from placing you and your family in danger.
[tab: The Solutions]
Electrical safety in the home is extremely important to take seriously! Every day we live around electricity and never give it a thought. That is until something happens and many times it is too late then. If you currently have appliances installed I would highly recommend that you hire a licensed appliance repair person to check and verify their installation. I do not advocate a homeowner who does not understand electricity to try this themselves. Yes it is a simple thing to do, but it is also a simple thing to electrocute yourself if you do not understand electrical safety.
If you are having new appliances delivered and installed you need to take precautions for the safety of your family. The following steps are ones you can take to help reach this goal of a safe home.
- Know your home’s electrical system configuration. That is do you have a newer installation with all outlets (both 120 VAC and 240 VAC) utilizing a proper safety EGC wire? If you are not sure then consult with a licensed Master Electrician who can review your system and provide estimates for any desired/needed corrections.
- Only purchase new appliances from a reputable store or dealer. All new appliances are required to be equipped with the capability for the safety EGC connection.
- If you are going to purchase used appliances only purchase them from a reputable dealer who will provide a written certificate of safety for the appliance.
- When you purchase your appliance make sure the dealer uses only properly licensed and trained appliance installers.
- When the appliance is being delivered and installed read the installation instructions before the installer begins. Ensure that they are following these directions properly.
- Always check the license of the appliance installer that comes to your home. Do not allow unlicensed persons to install your appliances!
Electrical safety for your home is nothing to ignore or take lightly!
[tab: Links and References]
Texas Department of Licensing and Regulation – Licensure of Appliancers Intallers/Maintenance and Electricians.
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