Step 4. Checking Customer Outlets
Check the power outlets before installing the system.
CAUTION:
Do not touch the receptacle or the receptacle faceplate with anything other than
your test probes before you have met the requirements in step 8.
This system may be configured for 220 V ac or -48 V dc power. If the system is going
to be used in a dc environment, you will need to have dc power cables and a dc power
supply.
Check the customer outlets as follows:
__ 1. Have the customer locate and turn off the branch circuit CB (circuit breaker).
Attach tag S229-0237, which reads “Do Not Operate.”
Note: All measurements are made with the receptacle faceplate in the normal
installed position.
__ 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 checks made in substeps 2 and 3 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 connections 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.
4 Installation Guide
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