Jason Palmer, CPA, CITP

Cyber Insurance Auditing

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Hurricane Tech – The Utility/Generator Transfer Switch

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An Extension cord is suitable for connecting the Generator to an individual device such as a TV set or major appliance but it limits you to devices that would normally be connected (plugged-in) to an electrical wall outlet.  If you want to connect a Generator to devices that are “hard-wired” to the Electrical Panel in your home or office, such as a Heating/Hot Water or Cooling System, or use the wiring in your home instead of Extension Cords, you need a “Utility/Generator Transfer Switch.”

This is a special type of electrical panel that has two inputs:  one for the normal electricity feed from the Power Company and one for the electricity feed from the Generator.  The output is a series of Circuit Breakers that replace the selected critical Circuits in the Main Electrical Panel that you want to provide Generator Power to in the event of a Utility outage.  Think the letter “Y”.  A Switch determines if Utility Power or the Generator is powering the Circuits.

Utility/Generator Transfer Switches come in two flavors:  Manual and Automatic.  As the names imply, the Manual Transfer Switch requires you to physically “Switch” the Power Source connection from the Utility Company to the Generator.  With an Automatic Transfer Switch, once the Transfer Switch senses a Loss of Electrical Power from the Utility, it waits approximately 30 seconds, and performs a series of tests to make sure there is a true “power outage” and it flips the Power Source from Utility Power to Generator Power.  (When power is restored from the Utility Company, you guessed it, with a Manual Switch you have to flip it back yourself while an Automatic Switch figures out the Utility Power is back and seamless flips the Switch for you along with powering down the Generator.)

An Automatic Transfer Switch only makes sense if you have an Electric Start Portable Generator or Whole House Generator that can be started “Automatically” upon sensing loss of Power from the Utility AND if the Automatic Transfer Switch is COMPATIBLE with the particular Generator configuration you have installed.

The amount of Generator Power you have available – Portable (usually under 8,500 watts) or Whole House (usually 15,000 to 20,000 watts), will determine the number of Circuits the Transfer Switch will support.   A Utility/Generator Transfer Switch for a Portable Generator will usually have a four to six circuits.

For a Whole House Generator, there may be almost as many circuits as on a regular electrical panel.  This will usually be ten or more Circuit’s.  When a Whole House Generator has sufficient capacity to power every device in the home or office, there may be a Single 100amp or 200amp Circuit Breaker which will exactly match the capacity of the Main Electrical Panel.

The Fuzzy Math Example:  A Portable Generator which produces approximate 8,500 Surge Watts at 120v Output will provide approximately 70 amps of “surge/start-up” power and 45 amps of sustained “full load” power.  A Utility/Generator Transfer Switch that has four 15amp Circuits which is a maximum load of 60amps is the proper size for the Portable Generator in this example.

IMPORTANT SAFETY NOTE:  Check with a LICENSED ELECTRICIAN for proper sizing and installation of any Utility/Generator Transfer Switch.  Failure to follow proper installation instructions may result in serious injury or death.  A Utility/Generator Transfer Switch is being connected to LIVE 120 volt ELECTICIAL POWER.  Use a professional, licensed electrician, preferably one with an explicit knowledge of Generator Power Systems to perform the work.

You are probably wondering, “I have way more than four circuits in my home.  What is the point of a Utility/Generator Transfer Switch that only supports four circuits?”

Answer:  Remember in the case of MOST Portable Generators and even a smaller Whole House Generators (Sub 15,000 watts), the purpose is to provide EMERGENCY and LIFE SAFETY power to CRITICAL Circuits in the home or office.  This would include the Refrigerator, Freezer, Heating System, Communications (TV, Internet, Phone), some Lighting and perhaps the Electric Ignition Starters for your Gas Oven, Stove, or Hot Water Heater and other critical Electrical Appliances.

To that end, the Circuit Breakers in the Utility/Generator Transfer Switch REPLACE the equivalent ones in the Main Electrical Panel.  When Utility Power is present, the Transfer Switch acts like a Sub-Electrical Panel.  The Circuits receive Utility Power exactly as if these Circuits were still in the Main Electrical Panel.

During a Power Outage, after the Power Source Switch is set to “Generator”, this entire Sub-Panel is COMPLETELY DISCONNECTED from the Utility Power and the power source is the Electricity from the Generator.

CRITICAL SAFETY NOTE:  The most important function of the Utility/Generator Transfer Switch is to connect EITHER UTILITY POWER OR GENERATOR POWER to the Circuits.  THE TRANSFER SWITCH ASSURES THAT ONLY ONE POWER SOURCE IS ACTIVE AT A TIME.  NEVER ATTEMPT TO BY-PASS THIS CRITICAL SAFETY FUNCTION.   Having both Utility Power AND Generator Power active on the same Circuit at the same time may result in Fire, Serious Injury, and Death.

Hurricane Tech – Extension Cords and Portable Generators

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When using a Portable Generator it is critical to have properly sized and grounded extension cords.  Portable Generators come with a variety of Outlet configurations depending on the Wattage rating and Amperage (Amp) output of the Generator.

At the minimum, all usually have at least one or two 15amp rated electrical outlets – similar to the type that you find on the wall in your home or office.  The next configuration is one or two 20amp rated outlets (the type your Refrigerator or Freezer or Air Conditioner might use) sometimes combined with either a 20amp or 30amp Twist-Lock outlet (used to connect to a multi-outlet box or Utility/Generator Power Transfer Switch.)  The take-away is that each Generator has its’ own outlet configuration and requires some thought as to how to connect it to the equipment in your home or office.

The important thing to remember when selecting the proper size extension cord for your Generator is that the higher the Amp output of the outlet, the thicker the copper wire in the extension cord needs to be to safely carry the electricity in to your home.  When selecting the correct gauge for an extension cord, the lower the gauge number the thicker the wire and the greater the capacity of the wire.  A 12 gauge extension cord can handle a greater capacity (Amp load) than a 14 gauge extension cord.  A 14 gauge extension cord more than a 16 gauge extension cord.

A 12 gauge grounded (three prong) extension cord can safely carry a 15 amp load up to 100 feet.  15amps is the most common circuit capacity of the electrical outlets in your home.  A 14 gauge grounded extension cord can only carry a 13 amp load the same 100 feet.

Higher amperage ratings may require 10 gauge cords depending on the distance. No Residential Home application should use an extension cord of more than 150’ without Professional guidance from a Licensed Electrician.

Every Underwriter Laboratories (UL Listed) extension cord is clearly marked with the gauge, maximum number of Watts and Amps it is safely capable of carrying.  NEVER EXCEED THE MARKED RATINGS OF THE EXTENSION CORD!

Try to use the shortest length extension cord possible to improve efficiency of the transmission of electricity from the Generator to the device to be powered.

If the generator has a 20 amp or a 30 amp Twist-Lock connector, this requires a special Generator Power Cord.  These cords will usually have the Twist-Lock connector for the Generator side and a multi-outlet box containing one to four 15amp or 20amp outlets on the other side. These special generator cords are usually 10 gauge or larger, depending on the length.  (Remember, larger wire has a lower gauge number.)    From this multi-outlet box, you can plug in standard extension cords of varying lengths to reach the equipment you want to power inside your home.

Any extension cord should be rated for Outdoor use because a Portable Generator will ALWAYS be outside AWAY from the house (to prevent carbon monoxide poisoning.)   If you live in cold climate, I strongly suggest investing in the “Cold Rated” cords that stay flexible when the temperatures drop.  Most Cold Rated cords come with the added benefit of heavy duty, resistant jackets that will hold up to rough garage floors, getting kicked around or walked over, and the elements.

If you need to convert a single outlet extension cord in to three outlets, use a specially made 12 gauge “pigtail” that has a 15amp heavy duty plug on one side and a heavy duty three outlet receptacle on the other side separated by a short length of heavy duty extension cord.  Standard three-to-one outlet adapters are made of plastic and may crack if stepped on as they are meant to be plugged in to a wall and NOT an extension cord.

Another nice feature to look for is cords that have an LED light in the outlet end to let you know that the cord is “energized” and “live” with electricity.  Given the fact that the Generator my run out of fuel and stop or be off for maintenance, the LED light gives 100% Positive feedback regarding the status of the power to your equipment.

In the case of expensive electronics like a Flat Panel TV, the Set-top Box, Internet Router or a Computer, connect an Uninterruptible Power Supply (UPS) to a 12 gauge extension cord to the Generator.  This provides added protection from surges and filters the power.  See my article “Hurricane Tech – Uninterruptible Power Supplies”

Personally, I always use 12 gauge, heavy duty, winter rated, grounded extension cords for an added margin of safety in 10’, 25’, 50’ and 100’ lengths.  By using a cord rated for the maximum 15amps, I am matching the rating of the Circuit Breaker on the Generator and I don’t have to worry about the extension cord failing.  The Circuit Breaker on the Generator should trip before the cord fails.  Since 15amps is the size of most household circuits, if I match the equipment I would normally plug in to a wall outlet to my 15amp Generator Circuit, everything is the same and therefore properly sized.

IMPORTANT SAFETY NOTE:  Periodically feel the extension cords to see if they are cold, warm, or hot.  If an extension cord is warm or hot, that means that you are exceeding the carrying capacity of the extension cord and should immediately un-plug it from the Generator or Power Source (Utility Power.)  Get a higher amp rated extension cord.  FAILURE TO DO SO COULD RESULT IN RISK OF FIRE.