Chapter 10 The Service Entrance
179
Copyright Goodheart-Willcox Co., Inc.
Service Completion
When the service entrance installation or
rough-in is completed, it will be inspected by
the electrical inspector. After this, the power
company will install the service drop or lateral
by connecting the wires from their transformer
to the service entrance conductors.
Figure 10-27 shows a typical completed
service entrance. Note the drip loops discussed
earlier, as well as the positioning of other
components in the fi nished service system.
3′
3′
10′
Figure 10-26. Clearances around building platforms
and openings.
Transformers
While the residential electrician will not be
working on transformers, it is helpful to under-
stand how transformers are made and how they
work. Due to the voltages involved, you should
be careful when working around this equipment.
Transformers are installed and serviced by trained
lineworkers employed by the power company.
Transformer Operation
A transformer has a relatively simple
structure, Figure 10-28. Basically, it contains
two coils of wire or windings and a common
Service entrance
cable or conduit
Insulators
Connectors
Weatherproof
connector
Service
head
Drip loops
Meter enclosure
Main panel, main disconnect,
and overcurrent devices
Meter
Earth
Branch
circuits
Ground conductor
Grounding means.
Elbow, sill plate or
entrance ELL
See B
Secondaries (service
drop) can be triplexed,
or spiraled 3 conductor
arrangement
Cable or conduit
anchor clamps
See A
A
B
C
Figure 10-27. Completed service entrance and
various fi ttings. Note relative position of compo-
nents and special fi ttings. A—Cable, conduit, or
anchor clamps fasten cable and conduit to structure.
B—Elbow, sill plate, or entrance ell protect conduc-
tors at point where they enter structure. (Hubbell, Inc.
and Electroline Mfg. Co.) C—Rain boot (not shown in
drawing) is used to protect from leaks when service
mast goes through roof.