Appendix B: Estimating The Cable Length You Need - EasyHeat ADKS Serie Guia Del Usuario

XI. APPENDIX B: ESTIMATING THE CABLE LENGTH YOU NEED
An accurate estimate of the cable length you need is important because you
cannot change the cable length by cutting, splicing or altering it in any way.
Doing so may result in fire, electrocution, or ice dam formation.
Cable should be installed on roof areas where ice dams form. This can be
the entire roof edge or specific areas such as beneath skylights, in valleys
or around dormers. Cable should also be installed in any nearby gutters,
downspouts and/or valleys.
• If you need to apply the cable on a roof with gutter, downspouts, valleys,
and/or dormers, follow "A. For Typical Roof Applications" below.
• If you only need to install the cable in the gutters only, follow "B. For
Problems in the Gutter Only" on page 21.
Table B-1 Cable Length Estimation Formula for Typical Roof Applications
Area What to measure
Along Roof Overhang (A)
Length along roof (B)
Dormer Distance around dormer (C)
Valley Number of valleys (D)
Downspouts Number of downspouts
Length of downspouts (E)
A
Overhang
Figure B-1.
Overhang Measurement
B
Figure B-2. Roof Measurements
20
D
• If you need to install the cable on a roof with special roof areas such as
a roof with skylights, follow "C. For Roofs with Special Roof Area Ap-
plications" on page 22.
A. FOR TYPICAL ROOF APPLICATION
STEP 1. For each area listed in Table B-1, measure the required dimen-
sions (see Figures B-1 and B-2) and calculate the length of cable
needed. Add each "area" calculation to determine the total cable
length needed.
How to calculate
Length of roof (B) X Overhang Multiplier (see Table B-2)
Number of dormers X Distance around dormer(s) (C)
Number of valleys (D) X 6 feet or 1.8 meters
Number of downspouts X Length of downspout (E) X 2
Table B-2 Overhang Multiplier
C
ROOF OVERHANG
Inches Centimeters
less than 12 less than 30
12 30
24 60
36 90
48 120
60 150
E
72 180
Note: For overhangs not listed, estimate multiplier. For example, for an 18" over-
hang with a gutter, multiplier will be about 4.7.
Multiplier Multiplier
For roof For roof
with gutter without gutter
4.0 3.0
4.0 3.0
5.3 4.3
6.8 5.8
8.1 7.1
9.6 8.6
11.2 10.2
ADKS Owner's Manual