General Breaker Recommendations; General Battery Installation Recommendations; Table 3-2 Heavy Gauge Wire Resistance Examples - Motorola GTR 8000 Manual

GTR 8000 Base Radio
• All AC power equipment and electrical components must conform to National Electrical Manufacturers
Association (NEMA) and National Electrical Code (NEC). These must also be listed by an NRTL.
• A surge arrestor, designed to protect equipment systems from a 120/240 V service and load center, is placed
on the power feed ahead of all individual load center circuit breakers. This gapless arrestor must be listed
by an NRTL for the purpose intended.
• Selection of a surge arrestor is based on the susceptibility of the equipment powered by the electrical service,
with margin provided for locally generated disturbances. See ANSI/IEEE C62.41 (21) for more details.
• At least one 120 V AC, 15 A duplex convenience outlet equipped with ground fault interrupter (GFI)
protection must be provided in the electronic equipment compartment.
Do not use surge/transient suppressors without careful and expert power system analysis.
Redundant devices could be terminated on different AC main phases so that a single phase failure does not
result in a power loss for both devices.

3.3.8.2 General Breaker Recommendations

In order to ensure that a fault which causes the breaker to open does not result in the loss of multiple transmit
channels, each base radio power supply should have its own supply breaker. The breaker recommendations for AC
and DC supply breakers are as follows:
• For a 120 VAC, 60 Hz application, the AC supply breaker should be rated for a continuous current of
20A. For a 220VAC, 50 Hz application, the AC supply breaker should be rated for a continuous current
of 10A minimum, not to exceed 20A.
• Individual DC breakers are not used. For information involving the sizing of cables and DC power
distribution, see the Standards and Guidelines for Communication Sites manual.
• Site installation shall include a single current interrupting device on the DC input distribution (fuse or circuit
breaker) rated for the application loading, not to exceed 200A. For each standalone base radio, the DC supply
breaker should be rated for a continuous current of 25A.

3.3.8.3 General Battery Installation Recommendations

The batteries and charger should be as close as possible to the rectifier system using the cables. A heavy gauge stranded cable
is advised to minimize voltage drop. Examples of the resistance of some heavy gauge wire is:
Table 3-2 Heavy Gauge Wire Resistance Examples
The maximum voltage drop can be calculated by knowing the peak current drawn by the radio system. Use the
following formula:
3-12
Gauge
#6 gauge
#4 gauge
#2 gauge
Resistance
0.3951 /1000 ft
0.2485 /1000 ft
0.1563 /1000 ft
6871022P86-A - November 2012