User Guide

4
SnoTrace
™
RGS
™
Systems for Roof and Gutter Snow and Ice Melting
Introduction
This design guide provides a basis for designing
a roof and gutter snow and ice melting system.
The amount of heating cable required and the
performance of the system is highly dependent
upon the following design parameters:
• Geographical location of project
• Orientation of building to prevailing wind and
weather
• Building design and construction
• Degree of protection required
1
Product Description
RGS self-regulating heating cable varies its heat
output to respond to changes in the surrounding
conditions. When covered by snow or ice, the heat
output of the cable automatically rises. Conversely,
when exposed to dry air the cable reacts by reducing
its heat output. This self-regulating feature occurs
along the entire length of a heat tracing circuit to
maximize snow and ice melting while conserving
energy. To ensure protection during installation and
for years of exposure to the elements, RGS includes
a tinned copper braid for grounding plus a heavy
polyolefin outer jacket containing a UV inhibitor.
For ease of installation, RGS is a cut-to-length
cable requiring no detailed dimensions of the
area needing protection and can be installed with
ordinary hand tools. It attaches to the roof with
cable roof fasteners and is routed into gutters and
downspouts with cable hangers. Circuit fabrication
kits designed for the application complete a
SnoTrace system.
To further simplify installation, the outer jacket
of each reel of RGS is printed with markers set at
approximate one meter intervals. This permits easy
installation of the cable directly from the shipping
reel since no premeasuring and cutting of the cable
is necessary. Simply keep the maximum circuit
length within the allowable range indicated in Table
2.1 on page 5 of this design guide.
Characteristics
Bus wire ............. 1.3 mm
2
(16 AWG) nickel-plated copper
Heating core .................. radiation cross-linked polyolefin
Primary dielectric insulation ..........................................................
radiation cross-linked polyolefin
Metallic braid...........................................................tinned copper
Outer jacket ...........................polyolefin (with UV inhibitor)
Minimum bend radius .........................................1.25" (32 mm)
Supply voltage......................................110-120 or 208-277 Vac
Circuit protection ...................................................................................
30 mA ground fault protection required
Nominal power output @ 0°C (32°F)
In snow and ice ........................................ 39 W/m (12 W/ft)
In dry air .......................................................... 20 W/m (6 W/ft)
Note
1. While entire roof areas can be electrically heat traced for snow and ice
removal, this design guide addresses only roof overhangs, gutters and
downspouts. Should your application require more area to be protected,
contact Thermon.
RGS Cables Meet or Exceed the Following Tests
Test Standard Followed
Abrasion Resistance UL 1588 (8.3); IEEE 515.1 (4.3.4)
Cold Bend ...................................................IEEE 515.1 (4.2.10)
Deformation ................................................IEEE 515.1 (4.2.8)
Dielectric Withstand ..............................IEEE 515.1 (4.2.1)
Resistance to Crushing .................................UL 1588 (8.1)
Resistance to Cutting ...........................IEEE 515.1 (4.3.3)
Resistance to Impact ................................... UL 1588 (8.2)
Temperature ............................................... UL 1588 (9.1-9.3)
UV and Condensation ..........................IEEE 515.1 (4.3.2)
Vertical Flame ....................................................UL 1588 (8.5)
Abrasion Resistant Polyolen
Outer Jacket (with UV inhibitor)
Bus Wire
E-Beam Cross-Linked
Semiconductive Heating Matrix
E-Beam Cross-Linked
Polyolen Insulation
Tinned Copper Braid
Product Approvals, Tests, and Compliances
Thermon’s SnoTrace RGS carries the following major
agency approvals:
Underwriters Laboratories Inc.
®
: RGS cables
and accessories are UL Listed specifically
as De-Icing and Snow Melting Equipment
(KOBQ).
Canadian Standards Association
Other approvals are also in place. Contact Thermon.
In addition to the numerous tests performed
by the approval agencies listed, RGS has also
passed the testing guidelines outlined in IEEE
Standard 515.1, Recommended Practice for the
Testing, Design, Installation, and Maintenance fo
Electrical Resistance Heat Tracing for Commercial
Applications.