Chapter 10 The Service Entrance
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• Service conductors should be kept as short
as practical to minimize voltage drop.
• Service conductors must enter the building
as close as possible to the service panel.
• The service disconnect must be at or very
near the point of entry.
• The service panel should be located in a
central and accessible area, near the major
electrical equipment of the building.
• The service equipment must be protected
from physical damage, water, and dust.
• Service equipment cannot be placed in bath-
rooms, storerooms, closets, or damp cellars.
Number of Services
A structure can have only one service. Thus,
each building will have one service drop or one
service lateral. While this is the basic rule, there
are some practical exceptions. The following
exceptions are allowed:
• A completely separate service is permitted to
supply a fi re pump or other emergency elec-
trical apparatus, such as lights or standby
power, Figure 10-4.
• If a single service cannot supply a large load
demand, another may be added.
• If structures are so large that no single
service would allow electrical access to
all the tenants of the building, additional
services may be provided.
• A generator, driven by an engine or wind,
may provide additional service.
• Electric power may be supplied by a solar
photovoltaic source in addition to the service
provided by the utility.
Figure 10-3. Service entrance specifi cations like these
should be secured from the utility company before the
service entrance installation. Refer also to the NEC and
consult the local electrical inspector whenever neces-
sary. (New York State Electric and Gas Corp.)
Service drop #1
Service drop #2
Main
disconnect
Disconnect
for fire water
pump
Figure 10-4. A separate service supply is permitted for
fi re pumps or other emergency electrical equipment.