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Extension Cord Safety

Extension Cord Safety TIPS

Select Right Size

I get quite a few questions each week about what size extension cord to use.

You may be one that's very worried about safety and electrical fires when using extension cords.

Talk with any seasoned firefighter and they'll tell you that extension cords are quite often the source of an electrical fire. There's a number of reasons why they're dangerous, but paramount is how it's easy for a cord to get overloaded with too much current.

Flowing Current Equals Friction

When a rough rope passes through your hand fast you'll almost always get a rope burn. It's caused by the friction of the rope fibers rubbing against your skin.

When electricity flows through a wire, it creates friction. The more current that goes through a wire, the hotter it gets.

If you want an extension cord to safely handle the load you've attached to it, then it better be big enough.

You have to stop and do a simple calculation as to the number of watts that will flow through the extension cord.

Most bulbs, tools, space heaters, and appliances have the wattage clearly marked on the label.

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Amps Easy To See

If you look at your circuit breaker panel in your home, you'll see odd black tabs. These are the flipper switches for common circuit breakers.

They always have a number somewhere on the flipper or the breaker. You'll commonly see the numbers 15, 20 and sometimes 30 or 40.

The most common number you'll see on most of the breakers is 15.

It stands for 15 amps.

IMPORTANT TIP: Fifteen amps is equal to 1,800 watts if your household voltage is 120 volts.

That's the standard voltage in the USA. Europe tends to be 240 volts for some reason.

All those confusing numbers are related in this formula:

Watts = Volts x Amps

Try it:  1800 watts = 120 volts x 15 amps

or how about this one: 2400 watts = 120 volts x 20 amps

CLICK HERE to get FREE & FAST BIDS from local electricians who will HELP YOU size an extension cord.

Why Circuit Breakers TRIP

Can you see how this helps you understand why you trip circuit breakers? If you have a toaster, a hair dryer and some lights on the same circuit and turn them all on at the same time, too much current is trying to flow through the breaker.

Circuit breakers are designed to protect the wiring in your home. When they sense too much current is flowing they SHUT OFF.

It TRIPS on purpose to prevent the wires in the wall from OVERHEATING which in turn causes a fire.

Wire or Cable Size

Above I talked about how larger sized wire can handle more current or heat. 

Wire size is stated in gauge to get you even more confused.

A 14-gauge wire is rated for 15 amps or 1800 watts.

A 12-gauge wire is rated for 20 amps or 2400 watts.

A 16-gauge wire or extension cords is usually only rated for 10 amps or 1200 watts.

When you look at the label of a heater, saw or any other electrical tool, you often see how many WATTS it draws. Use the above values to help you size the correct extension cord.

CAUTION: Don't think you can plug in a powerful table saw rated at 2400 watts or 20 amps into a 12-gauge extension cord and all go well.

Why? You may be plugging in the extension cord into a wall outlet that's only rated for 15 amps!!!!!

Wire New Homes With 12-Gauge Wire

This is why I hate to use 14-gauge wire when I wire homes. I always used 12-gauge wire when possible and the customer was willing to pay for the extra cost. It's so nice to know that you have plenty of wattage available on every circuit.

CLICK HERE to get FREE & FAST BIDS from local electricians who will HELP YOU size an extension cord.


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