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Idaho Power Underground Electrical Equipment Requirements
This document provides an overview of the requirements for installation and preparation of
underground electrical equipment. These requirements are intended to help ensure developers
and contractors comply with the National Electrical Safety Code, Idaho Power's requirements,
and industry best practices during the preparation and installation of electrical services. It is
intended for use by those involved in land use planning, excavation activities, and property
development.
Given there can be differences in county codes for residential and commercial subdivisions, each
code typically contains a section that requires plat maps to show the proposed utilities and
associated easements for placement of utility facilities. The following specifications and details
shall be incorporated to ensure clearance requirements are met from electric transformers to
structures, proper conduit installation, and sufficient easements are provided. Below are key
points and details associated with proper installation of electrical utility service equipment.
Easements
Our goal is to bring electricity to new and expanded subdivisions, safely and reliably. There are
many steps that go into accomplishing this important task but being able to safely install,
maintain and repair electrical infrastructure and facilities is critical. One way we do this is with
the use of easements. The following bullet points summarize what is needed to ensure electrical
equipment can be installed, maintained, and repaired:
Pad -mounted transformers require a minimum width of ten feet from the front lot line.
A side lot line width of five feet is required for trenching and service cable installation.
Contact Idaho Power if you are considering a zero -lot line build. While zero lot line
builds may be permitted, developers are required to leave room for necessary electrical
equipment, such as transformers, switches, and sectionalizing cabinets. This equipment
must be installed outside of the building footprint and meet minimum clearance
requirements.
Page 2 of 5
The diagram below illustrates the easement and setback requirements needed to ensure enough
room for installation of electrical facilities and other Joint Trench utility equipment. If
compliance with these details cannot be met, please contact Idaho Power.
MAIN LINE TYPICAL
(HORIZONTAL CONFIGURATION)
DISTANCE FROM SIDEWALK
10 PROPERTY LINE WILL VARY
M
TRENCH X-SECTION
DETAIL
x When [ sinmu.e m L.onl.1 m....nabrm.r.ne
P.e . ernre.m ee.umenr IfRpn reyobetf .1 en .... a Y.me
exa ct The wale. m.l.r. W.1., mnen re. ten rree. ne
nCouv mwall.e r benLne m..iy-0, For IN o ..non..n
easement Kre,n- Ib.n 10—, be r,. ree.
Joint Trench and Transformer Pad Easement Requirements
Page 3 of 5
Pad -mounted Equipment Clearances
Idaho Power requires two clearances from pad -mounted transformers, a working clearance and a
safety clearance.
Working Clearance
• A 10-foot operational working clearance is required by the National Electrical Safety
Code to safely access the high -voltage connections inside transformers and other
equipment. This requirement applies to the front of pad -mounted transformers and any
operational door on other pad -mounted equipment such as switches or sectionalizing
cabinets.
• A 10-foot clearance above most pad -mounted equipment is required in order to safely lift
and place (or replace) equipment.
• Keep shrubs, stored materials, fencing and the like a minimum of 3-ft from the sides and
back of pad -mounted transformers and other Idaho Power equipment to allow adequate
working space around equipment.
3' (min.)
on sides
3' (min.) in back 10' (min.) 1000-kVA and below
without doors 20' (min.) above 1000-kVA
10' (min.) in front
or sides with doors
3' (min.)
on sides
Working Clearance around Padmounted Transformer
Page 4 of 5
Safety Clearance
A safety zone is required around oil filled transformers. Combustible structures shall be
a minimum of 10 feet away from all transformer surfaces.
Habitable structures with less than a 3-hour fire rating (I -hour for non -sleeping
structures), air intakes, fire escapes or paths of egress are not allowed within 10-feet of a
transformer.
Nnn-comhusnhle Doors, operable windows,
wall or fire -rated air intake openings or
surface paths of egress
3' 3'
(min,) (min.)
10• 10' ^ _ _ 1 _ _ _ _ _ _ _
(min.) i
(min.)
I 1
1 t
t Padmovnted equipment
not allowed in this area-----------------
1
1
Clearance from a Non -Combustible Wall
Fire Resistant Barriers
A reduced safety clearance can be achieved by creating a fire-resistant barrier between a
transformer and the structure. The barrier is to be constructed of non-combustible materials and
meet all applicable building codes. An acceptable fire-resistant barrier is a free-standing wall
such as brick, CMU block or concrete that is located between the transformer and a combustible
building or surface. A minimum clearance of 3 feet is needed between the barrier and
transformer. The diagram below illustrates the reduced clearances that can be achieved.
Noncombustible
barrier by Customer
Combustible wall, door,
operable window, air
intake or fire escape
Do not overlook
,
a combustible eve
Path of
Non-comboatible
barrier by Customer
10'
egress
i-I
1 c
3'
min.J
Barrier must extend
JI in
-ii min. (min.j
to at least face of
I 3,
equipment
3'
JI r min. J
J'
-
10,
jmm.)
Fire -Resistant Barrier
Page 5 of 5
Conduit Installation
Developers have the option to install the conduit for residential underground electrical services
(electric service from a transformer or handhole to the metered service point) and shall follow
the installation requirements found on the Idaho Power website:
• The maximum service length is 125 feet and is the distance measured along the service
route between Idaho Power's equipment and the meter.
• The maximum radius bend is 135 degrees.
• The minimum depth requirement is 30-inches measured above conduit to final grade.
• Do not place handholes (electrical junction boxes) in driveways unless they are
constructed with a steel plate intended to take the weight of vehicular traffic.
The electrical service requirements for developers and builders can be found on our Idaho Power
website to ensure that they meet those in their construction and placement of improvements:
htti)s•//www idahopower com/accounts-service/construction-remodeLinglinstallinR-new-
service/residential-overheadunderground/
If you have any questions, please contact Idaho Power:
Jess Powell, Joint Trench Leader, 208-388-6399
Jon Axtman, Engineering Leader, 208-388-5036