15
“Beware of Using a
Continuity Checker!”
Our smaller Heating Rolls have a high Ohm resistance
and some continuity checkers do not send enough
current to get completely through the wire and emit
the noise or light that affirms proper continuity. If your
instrument cannot function on a small Heating Roll,
please use a digital Ohm meter.
Electrical Fault-Finding
Once the system has been turned off and made safe,
have a suitably qualified person:
1. Ensure all wires have been connected as per the
wiring diagrams.
2. Make sure multiple rolls have been wired in parallel
with all leads returning to the thermostat and not
hooked to each other in series.
3. Confirm that control devices are receiving correct
voltage.
Use a well calibrated digital Ohm meter with good
batteries. The Ohm resistance level of each Heating Roll
should be checked and the reading compared with the
resistance that was recorded during installation on the
corresponding UL label(s) (located on the circuit breaker
box) and in the log on Page 17 of this Manual. If your
reading is not within the 15%+/- range from the original
reading, the roll may be damaged in some way. If you get
zero across the core this indicates an open or short circuit
beneath the finished flooring. The electrical contractor
must locate the point of break or short, in coordination
with the Technical Services Department of WarmlyYours.
com.
Locating a Break or a Short
If your installation is complete, all wiring connections
have been verified to be correct, including grounding of
the system, you have checked the sensor wire for proper
Ohms reading, and you suspect the system is still not
working; you need to determine if there is a break or a
short under the floor.
Checking for Breaks
The Ohm resistance of each roll should be measured
across the core wires.
Make sure the probes of the Ohm meter do not touch the
sheath wire. Make sure you do not touch either of the
probe ends with your fingers, or the meter will be reading
your internal body resistance.
Make sure your Ohm meter is set on the proper scale (0-
to- 200 for Heating Rolls, or 0-to-20,000 for the sensor
wire). Your Ohm resistance readings should come within
15% (plus or minus) of the original measurement indicated
by the factory on the UL label.
If your Ohm reading is within 15% of what it should be,
there is no break. However, you still need to check for an
electrical short.
If your Ohm reading is lower (outside the 15% range), but
there is clearly some continuity, check your Ohm meter
and your batteries. If these are good, there is a possibility
that you have several electrical shorts.
Infinity Ohm Reading?
If you have absolutely no reading (= infinity on your
meter), and you are sure you adjusted the setting of the
Ohm meter to the correct reading range (0-to-200 for the
Heating Rolls, or 0-to-20,000 for the sensor wire), then you
have a break (= total cut) in the conductor.
Checking for Electrical Short
In some rare occasions an installation may have suffered
from a high pressure point that broke the insulation between
the core conductor and the multi-stranded sheath. Such an
opening in the insulation layer can create an electrical short,
even though the Ohm reading from the white conductor to
the yellow or red conductor is normal and does not indicate
any circuit break. In these rare occasions a continuity test
will show continuity between the one or both of the core
conductors and the sheath wire.
There should be no continuity (=“ infinite” resistance
reading, not zero) between the conductors and the sheath.
If your instrument reveals continuity between the core
conductor and the sheath, there is a short in the circuit.
Electrician’s Guide – Trouble Shooting
