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PROBLEM
Customer reports that
tool is frequently tripping
GFCIs
Customer reports
frequent Thermal
Protection trips, indicated
by Continuous Red LED
Revision 2 – May 28, 2019
ITEM
CAUSE & ANALYSIS
GFCI tripping due to normal leakage:
Extension cords, particularly long with
inferior/damaged insulation and certain
equipment can cause small amounts of
ground leakage. Alone these negligible levels
of ground leakage won't regularly cause the
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GFCI to trip. When this grinder is used in
addition to these low levels of leakage the
user may experience nuisance trips. Possible
problematic equipment includes plasma
cutters and lightening arrestors.
Confirm thermal trip. Thermal Protection and
Feathering Protection both share the same
LED code: a continuous red LED. The only
difference is that the Thermal Protection will
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reset by cycling the switch after the tool has
adequately cooled. The Feathering
Protection needs to be reset by cycling the
power; unplugging and plugging back in.
Intake or Exhaust blockage: The tool
requires airflow to adequately cool, this is
especially important for heavily loaded
applications. Inspect the intake screens to
determine if they are clogged from debris.
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Additionally, confirm that the user isn't
inadvertently blocking the exhaust with their
hand or blocking the intake with their body or
clothing.
Incorrect application / overload: In heavily
loaded applications, particularly those where
Large Angle Grinders are commonly used, it's
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possible to overload the tool resulting in
Thermal Protection shutdowns to prevent
permanent damage.
REMEDY
If GFCI is known to be good:
1. Remove other equipment
from circuit
2. Inspect or replace extension
cords, reduce length and
increase conductor size where
possible.
Refer to LED guide and user
manual for explanation of
features and LED codes.
With tool unplugged scrape or
blow clean the intake vents if
required.
Instruct user that blocking
intake or exhaust with clothing
or hand will reduce airflow and
could result in thermal trips.
After or between heavy loads
run the tool momentarily at no
load to allow the airflow to cool
the tool down.
Suggest altering application
bias or a larger tool (LAG).
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