I.S. SYSTEM 800
17A-13-I
11/03
PAGE 6 of 14
d) Bond the steel conduit or copper sheath of
MICC cable to earth at one point only within
the Hazardous Area. (Earthing via the I.S.
Interface box earth point is acceptable if the
box is situated close to the Hazardous Area).
6. INITIAL CONNECTIONS
a) At all devices to be connected to the circuit,
connect the LOOP IN and LOOP OUT wires
via a connector block, observing the correct
polarity.
b) To ensure continuity of cable screening, and to
prevent earth loops, the cable screen/copper
sheath should be joined at device positions and
insulated from earth..
c) At the last device, short LOOP IN (+ve) to
LOOP RETURN (-ve).
d) The insulation of the conductors should be
continued to a point as close as possible to the
connection. No loose strands of wire are
allowed.
e) Do not connect any devices at this stage.
7. CONTINUITY AND INSULATION
TESTS
If no Hazard exists or will not occur during installation, the
following tests may be carried out using a 500V megger with
the permission of the customer’s safety officer.
WARNING:
DO NOT USE A HIGH-VOLTAGE INSULATION
TESTER EG, MEGGER FOR ANY OF THE
FOLLOWING CHECKS. THESE TESTS MAY ONLY
BE PERFORMED USING AN INTRINSICALLY SAFE
INSULATION TESTER MEETING THE
REQUIREMENTS OF BS EN 60079-14.
7.1 CONTINUITY TESTS
Carry out the tests using a certified intrinsically safe ohmmeter
as follows in accordance with EN BS 60079-14: 1997 and
record the results:
a) To check the continuity, short-circuit the circuit
pair at one end of a loop.
b) To check the continuity of the cable screen,
short circuit the screen and one end of the
circuit pair at one end of the loop.
c) Locate and rectify any continuity faults by
quartering the circuit.
7.2 HIGH-VOLTAGE INSULATION TESTS
The following tests are carried out to ensure that no earths or
short-circuits have occurred during connection:
a) To test the high-voltage insulation between
conductors and earth, connect the insulation
tester between the circuit and earth.
A resistance reading above 1M ohm is
acceptable. Record the reading obtained.
b) To test the high-voltage insulation between
conductors, remove the short-circuit and
connect the insulation tester between the
circuit pair at the barrier end and measure the
insulation resistance. A resistance reading
above 1M ohm is acceptable. Record the
reading obtained.
c) To test the high-voltage insulation between
cable screen and earth, connect the insulation
tester between the screen and earth.
A resistance reading above 1M ohm is
acceptable. Record the reading obtained.
Locate and rectify any insulation faults using the quartering
method.
8. FINISHING OFF
a) At the barrier housing(s) and at all devices,
ensure that all metal chippings, cable snippets,
etc. are cleared away.
b) Replace all device and barrier housing covers
where applicable.
c) Ensure that copies of the cable routing
diagrams and copies of ALL circuit and
insulation tests are left in the barrier housing.
MK/jm/an
13
th
January 2003
www.acornfiresecurity.com
www.acornfiresecurity.com
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