King Electric SCM - Manual (Page 20)

20
Troubleshooting
If not qualified to perform electrical installations, it is strongly recommended that a qualified, licensed electrician be hired to install the heating
cables and related electrical components. If problems with the system arise, please consult the troubleshooting guide below. Any trouble-
shooting work should be done with the power removed from the circuit, unless otherwise indicated. Call the factory for further assistance.
SAVE THESE INSTRUCTIONS
TROUBLESHOOTING
Problem Possible Cause Solution
Mat/cable
resistance
measurement
is outside the
range printed
on the
nameplate
label.
An analog ohmmeter (using a
moving needle) was used to take Obtain a digital ohmmeter (multi-meter) able to read 0 to 20,000 ohms
( Ω) and re-measure the resistance.
If measurement shows an open or
short circuit, the heating cable has Record resistances between all power lead wires and contact the manu-
facturer.
If measurement is just a little low
or high, air temperature has af-
fected the resistance.
Place the mat/cable in a room 65-75 °F and re-measure after an hour.
The resistance measurement
could be from more than one mat/ Disconnect all cables/mats from each other and from controls and re-
measure.
The ohmmeter (multimeter) is set
to the wrong scale. If the ohmmeter (multi-meter) has multiple ranges (e.g. 200 Ω, 2kΩ,
20k Ω, 200kΩ, 20MΩ) set the range to 200Ω and re-measure.
Snow/ice is
not melting.
Mat/cable has been damaged.
Measure mat/cable resistances between all power lead wires as shown
in 7.7 of this manual. If there is an open or short-circuit damage, record
GFCI has tripped.
Try resetting the GFCI on the circuit breaker ONCE. If it trips again, do
not continue to try resetting it. Check for loose wire connections in the
breaker panel, junction boxes, controls, etc. Measure mat/cable re-
sistances between all power lead wires as shown in 7.7 of this manual.
If there is an open or short-circuit damage, record these resistances and
contact the manufacturer.
Incorrect voltage applied.
Briefly energize the system and use a multi-meter to measure the volt-
age between power lead wires of the mat/cable. Check voltage ratings
for each control and cable to make sure they match. If possible, use an
“amp clamp” meter to measure the
current into each mat/cable.
Mats/cables are connected in se-
ries.
Multiple mats/cables must be connected in “parallel”.
System
operates
continuously.
Incorrect wiring. Control was
“bypassed”.
Check wire connections. See wire instructions with control and
in this manual.
Faulty control. Relay is not opening
properly.
Check instructions with the control.
KING ELECTRIC MFG CO · 9131 10TH AVENUE SOUTH · SEATTLE, WA 98108 · PH:206 762 0400 · FAX: 206 763 7738 · www.king-electric.com