BEBCO EPS
Fuchs®Inc. • 1600 Enterprise Parkway • Twinsburg, Ohio 44087-2245 • www.bebcoeps.com
Telephone (330) 486-0002 • FAX (330) 425-4607 • E-Mail: [email protected]
15
Electrical Supply Requirements
Explosion
Proof Device
Typical Enclosure Wiring Methods
In a general sense, protected enclosures should be wired
similar to explosion proof enclosures, in accordance with
Article 500 of the National Electric Code - NFPA 70.
Single conductor wiring should be placed in rigid metal
conduit, seal-flex conduit or other mediums approved for
use in the hazardous location surrounding the protected
enclosure. Additionally, NFPA 496 requires the use of
approved seals on all pressurized enclosure conduit wiring
entries, in accordance with NFPA 70. Furthermore, the use
of an approved seal is simply the most practical way to
prevent excessive leakage through conduit connections.
However, while explosion proof enclosures require conduit
seals on all cable entries, in accordance with NFPA 70. Other
methods of sealed cable entries that are suitable for hazardous
locations can be used, such as compression glands.
In conclusion, there are two primary goals. First, the installer
should ensure that all associated wiring and cable is protected
by pressurization or other means, such as explosion proof
conduit or intrinsic safety barriers. Secondly, the installer
should ensure that all associated conduit and wireways are
sealed to conserve protective gas, unless they are used to
supply protective gas to other enclosures or devices.
Typical Enclosure Wiring Connections
Seal
Intrinsically
Safe Or Fiber
Optic Device
Adjacent
Pressurized
Device
Independently
Pressurized
Device
Intrinsically
Safe Or Fiber
Optic Device
Seal
Conduit
Conduit
Conduit
General Wiring Requirements
WARNING
THIS DEVICE CONTAINS ELECTRICAL PARTS WHICH
CAN CAUSE SHOCK OR INJURY
All electrical connections, conduit and fittings on the protected
enclosure must be suitable for the hazardous location in which
they are installed. In addition, all conduit and wire must be
installed in accordance with NEC as required and all relevant
plant and local codes.
Note:
Do not use seals on conduit used as a protected
“wireway” to supply protective gas to adjacent protected
enclosures. The same conduit can be utilized for both electrical
and pneumatic service to an adjacent protected enclosure(s),
provided the conduit is oversized to allow a minimum free
clearance equal to or larger than the pipe size required between
multiple enclosures as stated on page 7, “Getting Started”.
Enclosure Power Requirements
The protected enclosure(s) electrical power source must
originate from a circuit breaker or fused disconnect suitable for
the hazardous location in which it is installed. The switch must
be located within fifty (50) feet of the protected
enclosure(s) and the protection system and be properly marked.
Alarm Signal Requirements
For Type Y and Z purge systems, audible alarms or visual
indicators must be used to notify operators that pressure
inside the enclosure is below the NFPA minimum.
Alarms are connected directly to the enclosure and monitor
the differential air pressure between the enclosure and the
environment outside it. These alarms are activated by the
reduction in flow or pressure within the protective enclosure
and have a direct connection to the enclosure, eliminating
the need for an alarm on the protective gas supply.
•
The alarm must be located where the operator can see it easily.
• The alarm must take its measurement from the enclosure only.
• Alarms located in the hazardous area must be rated for the area.
• Valves cannot be connected between the alarm and the enclosure.
IMPORTANT NOTE
NFPA 496 requires the use of an alarm or an indicator to
detect the loss of safe enclosure pressure. In addition, the
NFPA 496 requires that if an indicator alone is utilized, a
protective gas supply alarm must also be installed between
the last valve in the protective gas supply and the protected
enclosure. Therefore, the protective gas supply to all LPS
Style systems must be equipped with the above mentioned
protective gas supply alarm. Exception: Systems utilizing
a P+F Model EPSK or GPSK enclosure pressure loss alarm
switch accessory will satisfy the above mentioned NFPA
requirement.
Gland
Fitting
Cable
Seal
Pressurized
Raceway
Protected Enclosure
Or Device
ISC * 877-602-0010 * www.iscenclosurecooling.com