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GFEP is the National Electric Code (NEC) required protection for fixed outdoor deicing and snow-melting equipment, which may be accomplished by using circuit breakers equipped with ground-fault equipment protection (GFEP) of 30 mA. It is important to understand that this required equipment protection is NOT the same as a 5 mA GFCI used for personal protection.
To ensure optimal performance, snow melting heating elements should be installed so that they are consistently 2"-3" from the finished surface. For installations using pavers, the maximum thickness for pavers installed over heating elements is 2.5".
Power requirements are measured in Amps and based on three factors: the watts per sq. ft. of the snow melting cable or mat, the area powered and the voltage used for the application. Our PowerMat product is rated at approximately 50 watts per sq. ft. (with 3" cable spacing), so that is a constant factor. Most snowmelt projects are powered with 240V AC – not all, but most. The one factor that is always variable is the area to be heated/powered. That is based on your project. For a point of reference, let's use the example of a 350 sq. ft. concrete patio.
The formula is (50 W/sq. ft. x area of 350 sq. ft.) / V (240V) = Amps, so 17,500 / 240V = 72.9 Amps
If a cable is damaged during installation, recheck the system for continuity and confirm the integrity of the insulation with a megohmmeter, or "megger" tester, referring to the installation and testing instructions. If the cable fails any of these tests, take the following actions: clear a 3 foot square working area around the damaged section of cable, and record the cable part number from the UL tag and the location where you purchased the product. Call WarmlyYours with the above information. WarmlyYours will provide further assistance and supply a splice kit suitable for repairing the particular cable.
To calculate the system's approximate operating costs, multiply the total kilowatts of the system by the cost per kilowatt in your area. Let's use the example of a 350 sq. ft. of concrete patio (residential application), with 240 VAC.
Total Watts: multiply area in sq. ft. x 50 Watts
350 x 50 = 17,500 Total Watts
Kilowatts: (the unit in we purchase electricity) take the Total Watts and divide by 1000
17,500 Total Watts / 1000 = 17.5 Kilowatts.
Kilowatt Rate: use the national average of .12 cents per Kilowatt-hours so how much do we pay for 17.5 kWatts?
17.5 kW x .10 = $1.75 for every full hour of operation.
Hours of Operation: We use a typical 6 hour snowfall for our example.
$1.75 x 6 hours = $10.50 for that snowfall.
All of this will vary due to "after-run time". "After run time" is where the system remains on extra hours after the snow has completed falling, to ensure complete pavement snow melting and drying.
Yes, as long as the paver isn't resting on exposed cable. The cable has to be embedded according to the installation cross section drawing.
Cover to an uncompacted depth of 1.5” (38mm), leveled to grade. A compactor that's applicable to the thickness and application can be used to compact the sand. The paver installer(s) must take care not to walk on the hot-cold factory splice and to avoid damaging the Heating Cables with shovels or rakes. At no time shall the compactor directly contact the wire.
Yes, WarmlyYours Snow Melting Heating System can be installed with quartzite stones. Start with 4” to 8” (102mm to 203mm) of crushed rock aggregate base. Rebar or wire mesh should be staked on top of this base and then heating cables or mats will be tied to this mesh with plastic zip ties. Heating system needs to be covered with 1” to 1.5” (51mm to 76mm) of finished mortar or sand. Stone Pavers will be installed on top but must NOT be any thicker than 2.5” (63.5mm). See cross-section in the documents section and in the manual.
No, a sensor is not required with the snow melt system. However, certain automatic controllers require a temperature/moisture sensor to sense atmospheric conditions and may also require an in-slab, high temperature limit sensor to be installed (notably, asphalt installations).
Yes. The NEC requires 2“ minimum of non-combustible material below, and 1.5“ minimum of non-combustible material above the heating cable.
The drawback is whether or not the pervious concrete will fail under load, thereby damaging the heating cable and voiding warranty. The cable should be attached to rebar in this case to insure the strongest support.
Reflective insulation is not effective with conductive heating, which is how embedded floor heating and snow-melting systems transfer heat. To be effective, the reflective insulation surface needs to face an air space (air gap), which allows the reflected heat to be redirected.
An effective solution considers the insulating material's R-Value. This is the rating of a material's insulating properties. The "R" stands for "resistance" and refers to the material's resistance to heat flow, or temperature conduction.