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

AC POWER SPD REQUIREMENTS CHAPTER 7: SURGE PROTECTIVE DEVICES
To Alarms Panel
(Recommended)
To Alarms Panel
(Recommended)
Shelter, equipment room or area.
SPD
(Surge Suppressor)
Type 1 SAD/MOV
SPD
(Surge
Suppressor)
Type 2 MOV
To Alarms Panel
Electrical meter and
service disconnect are
located outside the
equipment room or area
within another building or
structure.
Utility
Panelboard UPS
Automatic
Transfer
Switch
Main
Panelboard
with a main
breaker
Circuit
Breaker
Main Service
Disconnect
Type 3 SPD
optional
Meter
To Alarms
Panel
FIGURE 7-7 SPD INTERCONNECT BLOCK DIAGRAM ‘F’
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.
4. The Main panelboard shall use a main disconnecting device to serve the equipment area.
5. The Type 1 and Type 2 SPDs shall be installed per the manufacturer’s installation instructions.
6. All conductors between the SPDs 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 devices 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.
7-16 68P81089E50-B 9/1/05
UPS
Panelboard
Non-Critical
Loads
Critical
Loads
Generator
Step Down or
Isolation
Transformer
Utility Feed
AC
Type 3 SPD optional when greater
than 10 conductor feet from
panelboard.
240/120 Single Phase
208/120 3 Phase
480/277 3 Phase