OCTOBER 2005 PRE-INSTALLATION PROCEDURES 37
SIEMENS
MAINTENANCE MANUAL
2.6 CHECKING
GROUNDING
INTEGRITY OF FADAL
VMCS
2.6.1 SPECIFICATION -
GROUNDING FOR THE
FADAL MACHINE
1. MUST conferm to NEC code as stated in the Maintenance Manual.
2. MUST be a continuous wire 8 AWG or larger between the VMC's ground bus and
the building power distribution panel serving the VMC.
3. MUST be dedicated to a single VMC. (The ground and phase conductors cannot
be shared with any other equipment.)
4. Ground rods and other supplemental grounding may be used in addition to the
ground specified above but not instead of it.
2.6.2 INSPECTION -
CHECK GROUND
WIRE COMING INTO
VMC
1. The ground wire coming into the VMC and going to the building power distribution
panel must be 8AWG or larger.
2. The ground wire must be connected to the ground bar in the back cabinet of the
VMC. (It does not go to a screw in the disconnect box.)
3. The ground wire is to be a continuous wire from the VMC to the building power
distribution panel serving the VMC. The conduit is not to be used as the grounding
conductor. Ground rods and other supplemental grounding may be used in addition
to the ground specified above but not instead of it. Servicemen are not the
appropriate people to be inspecting power distribution panels or building wiring.
The serviceman is not expected to physically verify the routing of the ground
conductor, but should look for any indications that grounding is not as specified.
2.6.3 VERIFICATION -
CHECK GROUNDING
INTEGRITY WITH
FLUKE METER
1. Measure the resistance (ohms) of a length of 16AWG or larger wire that is long
enough to reach from the VMC to the building power distribution panel that supplies
the VMC. Record reading.
2. Attach the wire of step 1 (test wire) to the ground bus of VMC. The other end will be
used for measurement at the power distribution enclosure. (Do not open the
enclosure. Use a bare screw or bare metal on the enclosure for measurements.)
3. Set meter to AC Volts; with VMC on, measure and record voltage between the test
wire and the power distribution enclosure. Set meter to DC Volts; measure and
record voltage. Voltages should be OV with machine on but not operating, (up to
.O1OV is OK).
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