![background image](http://html.mh-extra.com/html/pentair/raychem-icestop/raychem-icestop_installation-and-operation-manual_1524280054.webp)
50
6
Commissioning and Preventive
Maintenance
Raychem-IM-H58067-IceStopRoofGutterDeIcingCOM-EN 18/01
5. Turn on the megohmmeter and set the voltage to
500 Vdc; apply the voltage for 1 minute. Record
the resistance.
6. Repeat step 5 at 1000 Vdc and 2500 Vdc.
7. Turn off the megohmmeter.
8. If the megohmmeter does not self-discharge,
discharge phase connection to ground with
a suitable grounding rod. Disconnect the
megohmmeter.
9. If the heating cable is installed on a metal roof,
metal gutter, or metal downspout, repeat these
steps with the negative lead (–) connected to
the grounding braid and the positive lead (+)
connected to the metal roof, gutter, and/or
downspout.
10. Reconnect the thermostat or contactor and re-
energize the circuit.
Insulation Resistance Criteria
A clean, dry, properly installed circuit should mea-
sure hundreds of megohms, regardless of the heat-
ing cable length or measuring voltage (0–2500 Vdc).
The following criteria are provided to assist in deter-
mining the acceptability of an installation where
optimum conditions may not apply:
• All three insulation resistance values should be
greater than 1000 megohms.
• Insulation resistance values for any particular
circuit should not vary more than 25 percent as a
function of measuring voltage.
• Reading must be steady at measuring voltage.
• If any of the above conditions are not met, consult
“Troubleshooting‚” Section 8.