standards and guidelines for communication sites - Radio And ...

STANDARDS AND GUIDELINES FOR COMMUNICATION SITES AC POWER SPD REQUIREMENTS
To Alarms Panel
(Recommended)
Shelter, equipment room or area.
SPD
(Surge Suppressor)
Type 1 SAD/MOV
To Alarms Panel
Electrical meter and
service disconnect are
located outside the
equipment shelter,
room or area typically
within another building
or structure.
UPS
Utility
Panelboard
with a main
breaker
Step Down or
Isolation
Transformer
Circuit
Breaker
Main Service
Disconnect
Type 3 SPED
optional
Meter
FIGURE 7-4 SPD INTERCONNECT BLOCK DIAGRAM ‘C’
NOTES: 1. The main service disconnect is located outside the equipment shelter, room or area, typically within another building or structure.
2. The service to the equipment shelter, room or area is 3 conductors with ground for single phase or 4
conductors with ground for 3 phase.
3. The step-down or isolation transformer creates a separately derived system where the neutral and ground conductors are
bonded together within the transformer and bonded to the equipment room MGB. The main disconnect ground and the MGB
shall be bonded to the site grounding electrode system at the same point.
4. The Utility Panelboard shall use a main disconnecting device to serve the equipment area.
5. The Type 1 SPD shall be installed per the manufacturer's installation instructions.
6. All conductors between the SPD and the associated disconnecting device shall be as short as possible and routed together
with a minimal number of bends or angles of less than 90 degrees.
7. The SPD disconnecting device should be installed in the top most space available in the Utility Panelboard.
8. Installation of Type 3 SPDs on each critical load is recommended where the level of exposure is high.
9. Installation of Type 3 SPDs on each non-critical load that is located greater than 3 m (10 ft.) of conductor length from the
panelboard is recommended where the level of exposure is high.
68P81089E50-B 9/1/05 7-13
UPS
Panelboard
Non-Critical
Loads
Type 3 SPD optional
when greater than 10
conductor feet from
panelboard.
Critical
Loads
Utility Feed
AC
240/120 Single Phase
208/120 3 Phase
480/277 3 Phase