Installation
Reference Manual
June 2016
MAN-0076, Revision 09
6
Installation
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Detection instruments
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Customer connected equipment
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Wiring
Net Safety designs and manufactures its detection equipment under rigid quality control management
systems and makes every effort to design for the harshest of industrial environments. The other
components of the system – the customer-connected equipment and wiring – are also important
contributors to the overall quality and performance of the safety system.
It is important to implement wiring that ensures the reliability and integrity of the safety system. Field
wiring practices and the choice of cable type specified vary from project to project. Poor practices and
choices are often found to be the source of unwanted system disruptions. RFI and electromagnetic
interference (EMI) are usually very powerful disruptive forces in industrial facilities and these forces act
upon the system through the wiring.
The cable used should be a very high quality instrument grade, certified for the application conditions,
consisting of a rugged protective outer jacket, an overall electrical shield of fine braided copper or
metallic foil, and internal pairs or triads of foil shielded copper wire of suitable gauge for the power
conducted over the specified length.
The shields must be electrically continuous from the instrument junction box through other junction
boxes and finally to the connected equipment. The shield must be connected to a suitable ground sink
as specified in the instrument manual in order to protect the system from electrical disturbances.
In general, communication cables and power cables should not run in parallel for any significant length,
and should not be carried in the same cable tray. Through inductance, high currents in power cables
can induce significant ‘noise’ in communication cables running parallel alongside power cables.
2.4.5
Internal ground screw
To access enclosure grounding screw, remove the electronics module by following steps 1 through 7 in
Section 2.3.2.
2.4.6
External ground
In order to ensure proper operation of the sensor, an external earth ground is recommended. Net
Safety recommends that the external ground be connected to the grounding point on the enclosure.
2.4.7
Seals
The use of seals is recommended to further protect the system against water ingression, and
equipment should be installed according to applicable local electrical codes. Seals are especially
recommended for installations that use high-pressure or steam cleaning devices in proximity to the
transmitter.
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Waterproof and explosionproof conduit seals are recommended to prevent water accumulation
within the enclosure
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Seals should be located as close to the device as possible and not more than18 inches (46 cm) away
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Explosionproof installations may require an additional seal where conduit enters a non-hazardous
area; ensure conformity with local wiring codes
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When pouring a seal, use a fiber dam to ensure proper formation of the seal. Seals should never be
poured at temperatures below freezing