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Installation and Operation Manual
Grounding
The SPD has leakage current to ground when energized and can present a
hazardous touch voltage.
The device has SPD elements connected from phase to ground. To prevent
hazardous touch voltage on the SPD enclosure during normal operation or
during SPD end-of-life, it is critical that there be a robust and effective
connection to the building grounding structure. The grounding connection must
utilize an equipment grounding conductor run with the phase and neutral (if
present) connection of the power system. The SPD should not be connected to
a separate isolated ground.
When metallic raceway is used as the wiring method, an insulated grounding
conductor should be run inside the raceway and sized in accordance with all
applicable codes. Maintain electrical continuity at all raceway connections using
appropriate bonding devices and do not install isolating bushings to interrupt a
metallic raceway run.
For best overvoltage suppression by the SPD, use a single-point ground
system where the service entrance grounding electrode system is connected to
and bonded to all other available electrodes, building steel, metal water pipes,
driven rods, etc. (for reference, see IEEE 142-2007). The ground impedance
measurement of the electrical system should be as low as possible, and in
compliance with all applicable codes.
SPDs rated for use on solidly-grounded power systems must not be connected
to resistance-grounded (for example HRG) or ungrounded power systems.
Such a connection can result in damage to the components within the SPD.
WARNING
HAZARDOUS TOUCH VOLTAGE
• Connect the SPD ground terminal to the building grounding grid
structure.
• Use an appropriately sized equipment grounding conductor.
• When using metallic raceway or conduit:
— Do not use the SPD ground unless augmented with an insulated
equipment grounding conductor installed inside the metallic raceway or
conduit.
— Do not use isolated bushings to interrupt the metallic raceway or
conduit.
— Maintain electrical continuity at all raceway and conduit connections
using appropriate bonding devices.
• Do not use a separate isolated ground for the SPD.
• Verify proper equipment connection to the grounding system.
• Verify ground grid continuity by performing regularly scheduled
inspections and testing as part of a comprehensive electrical
maintenance program.
Failure to follow these instructions can result in death or serious injury.
Grounding