User Guide

DESIGN GUIDE
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Example
To determine the recommended amount of cable for a standing seam metal roof under a heavy snowfall rate
with 350 mm seams/ridges and a 450 mm overhang use Table 3.1 on page 6.
Using the column for 350 mm seams/ridges and the row for an 450 mm overhang indicates the application
would require 4.2 m of cable per linear meter of roof. Therefore if the length of the roof was 30 x 4.2 =
126 meters of cable for the roof surface (additional cable required for power connection, see complete
calculations below).
Continuing with the example, refer to Table 3.3 on page 7 to determine the amount of cable required for a
300 mm gutter with 3 downspouts that are 4.5 m in length.
Using the row for 150-300 mm gutter widths indicates that a 2x multiplier should be used for the total
gutter length and downspout length. Therefore the total length of roof 30 x 2 = 60 meters for the gutters.
Additionally, each 4.5 m downspout would require 4.5 x 2 = 9 meters of cable. Multiply this total times three
downspouts: 9 x 3 = 27 meters for the three downspouts.
As the example will have 240 Vac, single phase power available, RGS-2 is selected. To optimize the circuit
length potential, two 30 A circuits will be utilized. Be sure to add sufficient extra cable to reach the power
connection point for each circuit. In this example 0.6 meter per circuit is sufficient.
Roof length .................................................. 30 x 4.2 = 126
Gutter length .................................................. 30 x 2 = 60
3 Downspouts ......................................3 x (4.5 x 2) = 27
2 Power connections .................................2 x 0.6 = 1.2
214.2