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What's the difference between low and high voltageYou’ll find that working with electrical wires and circuits exposes you to a wealth of new terms.  The most common are components such as resistance, current, and voltage.  But on occasion you’ll find voltage split into two ratings, low- and high-voltage wiring.  This can be confusing for many people since, unfortunately, the cutoff point for what is known as high-voltage wiring is based on context, rather than a hard-set standard for what is high voltage.


Voltage is simply the difference in electrical potential between two points.  It’s one of many measurements we use to rate different devices and is the most common term known by the layman when it comes to electronics.  Saying an electrical line is a “œhigh-voltage line” is understood by most as being a dangerous wire that should not be touched.  So, context-wise, high voltage is anything that has the potential to cause severe harm or injury.

The IEC does have a standard rating for high and low voltage in the US:

High Voltage: Electrical devices and lines over 1,000 volts for AC circuits and 1,500 Volts for DC circuits

Low Voltage: Electrical devices and lines between 50 and 1,000 volts for AC and 120 to 1,500 volts for DC circuits

By the IEC’s ratings system, all home wiring is low voltage wiring (with extreme low voltage wiring being used in most electronic devices and simple circuits).  In fact, with an increasing number of homes installing USB outlets, landscape lighting, and distributed cable networks throughout the home, extreme low-voltage wiring has become more common than standard voltage.  Many homeowners have a tendency to call the 120- 240-volt AC and appliance wiring “œhigh voltage” when it really isn’t.  A better term (and one used by electricians) is line or mains voltage.

How are they Used?

A better way to illustrate the differences is by showing how they’re used in your home.  True high-voltage wiring usually exists in only one part of your home, the interconnect between your home’s electrical system and the municipal power grid.  The high-wire lines running through your city operate at 33 kV (33,000 volts).  Which is small compared to the 110 kV (and higher) lines used for transmission outside of cities.  Everything else in your home is likely to be labeled low-voltage or extreme-low voltage.

Your home’s electrical system consists of low-voltage wiring.  Here in the US, our homes use a simple 110- to 120-volt electrical system.  Dedicated appliance circuits and some garage or workshop circuits offer 220- or 240-volt outlets for special devices, but this is still well-within the operating requirements for low-voltage wiring.  Even the lighting in your home operates on this simple low-voltage wiring.  As powerful as you feel that 100-watt incandescent is, it still uses 120-volt AC electricity to power itself.

Where systems become interesting is in the extreme-low voltage range.  Outdoor and landscape lighting are the best example of this.  While Ethernet, phone lines, and entertainment system wiring are all extremely low-voltage wiring (data signals often use as little as 5-volts DC for signal transmission), outside lighting is the best example of low-voltage wiring around.  Path lights, bullet flood lights, and well lights typically operate on 12- to 24-volts of DC electricity.  This is for safety reasons as outdoor cables are usually exposed so a lower voltage improves safety against water electrocution or accidental damage to the electrical cable while mowing the lawn or doing yard work.

So in the end, the difference is simple how much voltage is being used.  Most people will never encounter high voltages in their lifetime.  If you do, stay away.  Anything that’s been labeled “œhigh voltage” is extremely dangerous.  Call your utility company if you suspect damage and always stay away from any high voltage line, even if it looks dead.

Hickerson Electrical is your source for all home electrical services.  We’re ready and willing to deliver top-quality service to your home at a moment’s notice.  So call today at (703) 594-3913.

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