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The IEE Code
of Practice for In-Service Inspection and Testing of Electrical Equipment
provides specific information on the inspections and tests
necessary. The following is our PAT testing policy which
incorporates the recommendations of the code: -
Formal visual checks.
The
Code requires that in addition to user checks, formally documented visual
checks are routinely carried out.
Earth Bond Test.
Class I
equipment normally conducted from 6A to 25A. This test is for
checking the integrity of the resistance of the safety earth
connection
Earth Screen Test.
Used to
test I T equipment (e.g. computers, copiers etc) which require a low earth
“screen” current of 100mA (Sometimes called business equipment or I.T.
test). This is to prevent damage to the equipment.
Insulation Test.
For
class I and II appliances, this is normally conducted at 500VDC, with
option of applying a 250V test where mains input filters might give
misleading readings.
Earth Leakage Test.
For
class I and II appliances, used where insulation testing is not
recommended. The current flowing into the appliance via the supply cable,
is compared to that flowing out. Any difference must be leaking to
earth, either via the earth lead (class 1) or the case or other connection
(class 2).
Flash Test.
This is
a very severe test and can cause damage to equipment. Flash tests are
normally only carried out to equipment that has been repaired or sustained
damage.
Inspection.
Formal
documented visual checks are carried out by experienced engineers,
qualified to City
& Guilds 2377/01 (Certificate Of Competent Management Of Electrical
Equipment) and City & Guilds 2377/02 (Certificate Of Competence For The
Inspection Of Electrical Equipment) These inspections include
checks for safe wiring, condition of cable/flex, correct fusing and any
sign of overheating, damage or incorrect operation.
Test Equipment and Calibration
Only
when the test engineer is satisfied with the visual checks, is the
appliance connected to the test equipment. Modern computerised Portable
Appliance Test (PAT) Equipment is used for testing. This equipment is
capable of carrying out all the tests necessary under the Code of Practice.
The test results are stored by this equipment and downloaded to a computer,
to provide accurate test result documentation. The
equipment used is regularly calibrated and is also checked
for accuracy before every testing session.
Disconnecting Computers and Sensitive IT
Equipment.
Equipment
to be tested normally has to be disconnected from the mains supply. We can
however test certain IT equipment (servers etc) without disconnection, thus
avoiding any of the potential problems associated with re-booting.
Any equipment that is connected at the time of the test is only
disconnected after permission to do so is obtained from the user or a
department manager. This is particularly important in the case
of IT equipment and security cameras etc.
Fault Rectification.
Equipment
will not be failed because of faulty plug-tops or incorrect fuses. These
will be replaced automatically before testing, for a small charge.
Other repairs can be carried out on-site. Estimates will be supplied.
Labeling and Identification.
All
appliances and cord-sets are labelled and given a unique I D. This enables
us to track test results over the long term, and make sure that tests are
carried out without fail at the appropriate intervals. In addition, PASS or
FAIL labels are affixed to the tested appliance, with the test date and the
re-test date. The labels are affixed in a position where the user can
see at a glance, the status of the equipment. If required, we can
supply labels to your specification.
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