IBM eserver p Series, Installation Manual

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__ 2. Some receptacles are enclosed in metal housings. On receptacles of this type,
perform the following steps:
a. Check for less than 1 volt from the receptacle case to any grounded metal
structure in the building, such as a raised-floor metal structure, water pipe,
building steel, or similar structure.
b. Check for less than 1 volt from receptacle ground pin to a grounded point in
the building.
Note: If the receptacle case or faceplate is painted, be sure the probe tip
penetrates the paint and makes good electrical contact with the metal.
__ 3. Check the resistance from the ground pin of the receptacle to the receptacle
case. Check resistance from the ground pin to building ground. The reading
should be less than 1.0 ohm, which indicates the presence of a continuous
grounding conductor.
__ 4. If any of the three checks made in substep 2 are not correct, ask the customer to
remove the power from the branch circuit and make the wiring corrections; then
check the receptacle again.
Note: Do not use the digital multimeter to measure grounding resistance.
__ 5. Check for infinite resistance between the phase pins. This is a check for a wiring
short.
CAUTION:
If the reading is other than infinity, do not proceed! Have the customer
make necessary wiring corrections before continuing. Do not turn on the
branch circuit CB until all the above steps are satisfactorily completed.
__ 6. Have the customer turn on the branch circuit CB. Measure for appropriate
voltages between phases. If no voltage is present on the receptacle case or
grounded pin, the receptacle is safe to touch.
__ 7. With an appropriate meter, verify that the voltage at the outlet is correct.
__ 8. Verify that the grounding impedance is correct by using the ECOS 1020, 1023,
B7106, or an appropriately approved ground impedance tester.
Note: Do not use the 120-volt convenience outlets inside a machine to power
the tester.
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Installation Guide