King Electric SRP self-reg, preassembled - Manual (Page 4)

Use the number in the table and multiply it by the length of the roof edge.
CALCULATIONS FOR GUTTERS, DOWNSPOUT AND VALLEYS:
1. For standard non-metal roofs, add 1 foot of heating cable for
each foot of gutter.
2. Add 1 foot of heating cable per foot of downspout.
3. If the downspout is in the middle of the run, loop the cable
down and back up. Double the length of the downspout for
determining the length of cable to install.
4. For valleys, run the heating cable two thirds of the way up and
down the valley. Add this additional length to the overall cable
needed.
5. For gutters 6 inches wide use two cable runs.
Selecting the Required Heating Cable Length for Roof and Gutter Deicing
Eave
Overhang
Standard
Roof
Metal Roof
18” Seam
Metal Roof
24” Seam
None 2.0 2.5 2.0
12” 2.8 2.8 2.4
24” 3.8 3.6 2.9
36” 4.8 4.3 3.6
Heating Cable Multiplier Table
ELECTRICAL CODES
Article 426 of the National Electrical Code (NEC), and Part 1, Section
62 of the Canadian Electrical Code (CEC), govern the installation of
SRP heating cables for roof and
gutter deicing and must be followed.
IMPORTANT: For the warranty to be valid, the installer, customer and
user must comply with all the requirements outlined in these guidelines.
All design information provided in these instructions are based on a
“standard” shake or shingle and metal roof applications. For any other
application or method of installation, consult a design specialist.
GENERAL INFORMATION FOR ROOF AND GUTTER DEICING
1. SRP cable is designed
to remove ice, not accumulated snow.
2. SRP cable will not keep snow or ice from falling off of the roof .
Snow fences or snow guards should be used to eliminate snow
movement.
3. SRP heating cables may be used on:
- Roofs made from all types of roofing materials, such as
shake, shingle, rubber, tar, wood, metal, and plastic.
- Gutters made from standard materials, such as metal
and plastic.
- Downspouts made from standard materials, such as metal
and plastic.
4.Do not use an extension cord.
5. Do not install the heating cable underneath any roof
covering.
6. Install only in accessible locations; do not install behind
walls or where the cable would be hidden.
7. Do not run the heating cable through walls, ceilings, or floors.
8. Connect only to ground-fault protected outlets that have
been installed in accordance with all national and local codes
and standards
and that are protected from rain and other water
sources such as melting ice water.
9. SRP cable is factory preassembled and cannot be altered.
Use of any in-line splices or tee-splices will void the warranty.
Cut to length cable is available from King, contact your local
distributor or visit the King website for information.
10. Do not exceed the amp rating of the over current
protection device.
Figure 5: Roof and Gutter Application
CALCULATION FOR HEATING CABLE LENGTH:
Use the formula below to determine the amount of heating
cable required. Total heating cable length = A+B+C+D
A (Roof edge) × (heating cable multiplier)
B (Roof edge x 0.5)
C ( Total gutter length)
D (Total downspout length + 1 ft)
= Total heating cable length required
Example:
1. Roof edge = 14 ft
2. Eave overhang = 1 ft (Refer to cable multiplier table)
3. Gutter = 14 ft
4. Downspout = 12 ft
Heating Cable Required:
A Roof edge: 14 ft × 2.8 (Multiplier from table) = 39.2 ft
B Roof extension:14 ft x 0.5 = 7.0 ft
C Roof gutter: 14 ft = 14.0 ft
D Downspout: 12 ft + 1 ft = 13.0 ft
Total heating cable length required: = 73.2 ft
Example Solution = SRP126-75
*Roof extension is the length of cable required to prevent ice
dams between the roof edge and the gutter. When there are
no gutters present it forms a drip loop to prevent ice dams at
the roof edge.
Rev 8.19.12 www.king-electric.com 4