White Paper
More Meaningful Connections
WHITE PAPER – VeriSafe
™
– Update to the NFPA 70E Standard
Part of the motivation for including Exception 1 was to stimulate original
solutions and development of new technology for safety applications
and make testing for an absence of voltage safer and more ecient. For
example, when performing the traditional method of using a hand-held
voltage tester to check for an absence of voltage in a control panel, the
door must be open to conduct the test. This exposes the electrical worker
to potentially lethal voltages. However, implementing AVT devices allows
the worker to verify the absence of voltage prior to opening the panel
which reduces the risk of an electrical incident.
Meeting Exception 1 of NFPA 70E-2018,
Section 120.5 (7)
While several devices on the market seem to meet the requirements
detailed in Exception 1, it is important to thoroughly examine each of
these devices to determine if they suciently satisfy the criteria set forth.
Voltage Test Portals with a Hand-held Voltage Tester
Voltage test portals are sometimes installed on equipment so workers can
use hand-held voltage testers before opening the enclosure. However,
this combination does not meet the requirements of Subsection C since
there is no way to confirm that the probes of the hand-held tester are in
direct contact with the electrical conductors inside the enclosure.
Additionally, the use of a hand-held tester requires access to a known
voltage source to verify the tester is functioning.
Panel Meter
Although it may appear that a panel meter would meet the requirements
of Exception 1, the problems lie with Subsections B, C, and D. Subsection
C dictates that the tester analyzes each phase from phase-to-ground and
phase-to-phase. In-panel voltage meters are hard wired and are installed
only to measure phase-to-ground voltage.
A panel meter cannot self-test and determine proper operation. A panel
meter checking for voltage may be defective and therefore may not
indicate that voltage is present and that the panel is energized. Another
cause for mis-indicating that a voltage is not present is if one of the
sensing leads has dislodged and is no longer connected to the line.
Because of these limitations, panel meters cannot be listed for verifying
the absence of voltage and do not meet the requirement in Subsection B.
Risky Business: Potential Electrical
Hazards Exist When Performing
Absence of Voltage Testing
TEST THE TESTER
CHECK THE VOLTAGE
RE-TEST THE TESTER
TRADITIONAL METHOD
Determining absence of voltage with
hand-held testers presents a risk of
exposure to electrical hazards