After shoveling your driveway all winter long, you’ve decided to make it the last season you’d ever have to suffer that back-breaking labor again. Before next winter rolls around, you’ll have a brand-new snow-melting system resting under your driveway, waiting in the wings for snow to fall.

Snow Melting Page - Slide #5

If you have a standard-size driveway, you likely can use a basic controller to keep your system working when it needs to. However, if you have a large driveway, you may want to consider a multi-zone controller.

According to, a typical double-car driveway is 20 feet wide and between 18 and 20 feet long. That means approximately 84 amps (or 4 circuits) at 240 volts are needed to power the system. If you double the length of the driveway, you would need 167 amps (or 7 circuits) at 240 volts to power the system. Not many homeowners have 7 circuits available in their breaker panel; therefore, they would have to upgrade their circuit panel in order to supply enough power. Unfortunately, doing so is a significant expenditure.

To address this issue, WarmlyYours recently introduced its Power Modulator 3 control, which allows homeowners to split the load into multiple zones, eliminating the need to upgrade their power supply.

The Power Modulator 3 control enables multi zoning for snow-melting systems.What is Zoning?

Zone coverage is a compromise solution that allows two to three times more square footage to be heated than would be normally available. For example, if a driveway requires 150 amps to heat the entire area and only 50 amps are available, the driveway can be split into three zones using 50 amps per zone. WarmlyYours’s Power Modulator control works by switching on one zone at a time and sequencing the zones to eventually melt all of the snow. Because only one zone is powered at a time, it will take longer to melt all of the snow on the driveway, but this is a great option for large driveways that wouldn’t be able to use a snow-melting system otherwise.

Calculating Your Power Requirements

How to calculate your power requirementsTo find out the amperage and number of circuits needed to power a snow-melting system for your driveway, you can use the formula below.

1. Determine the square footage of your driveway by multiplying its width by its length.

2. Multiply the square footage by 50, which is the number of watts needed for the heating cable to melt snow.

3. Divide this number by the voltage type available (120, 208, 240 or 277). This will provide you with the required amperage.

4. Finally, divide this number by 24 and round up. This gives you the number of circuits required to power the system. Note: This number may increase depending on the number of rolls/cables needed to heat the area.

To demonstrate this formula, let’s take a look at the 20- by 40-foot driveway that was mentioned earlier. First, we need to multiply 20 by 40 to get the square footage: 800. Then, we multiply 800 by 50 watts, which gives us 40,000. Let’s imagine that the voltage for this hypothetical home is 240 volts. In that case, we will divide 40,000 by 240 to get 166.66 amps. When you divide this by 24, you get 6.94, which should be rounded up to 7 circuits.

Each heating cable or roll also will require a relay pole or two, depending on the voltage available. To determine how many relay poles you will need, you’ll just need to know your voltage type. 120- and 277-volt heating cables/rolls require one relay pole per cable/roll; 208- and 240-volt heating cables/rolls require two relay poles per cable/roll.

Of course, if you have any questions about your snow-melting system and its requirements, WarmlyYours’s technical experts are available to help. Call them any time, 24/7, at 800-875-5285 and they will happily assist you.

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