Commercial Service Requirements
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Section D - Meter Requirements
This chapter gives you information on Central
Lincoln’s metering requirements. It's divided into three sections:
This section contains the requirements that pertain to all meter
installations such as meter location, clearances, and multiple meter
installations.
Self-contained metering
This section contains the requirements for single-phase (up to 400 Amps -
see Table 2) and three-phase service up to 200 Amps.
Instrument Transformer metering (CT’s & PT’s)
This section contains the requirements for single phase and three-phase
service over 200 Amps.
GENERAL REQUIREMENTS
Removing
and Installing Meters
Only authorized and qualified
Central Lincoln personnel shall cut seals, and remove or install meters. Under
emergency conditions, exceptions may be granted to qualified electricians by
contacting either the Central Lincoln Meter Department or the service office.
When this occurs, the party shall accept all liability for damage or alteration
to equipment, injury to persons or property, and loss of revenue to the utility
from the time the seal is removed until the equipment is ready to be resealed.
The customer or contractor shall promptly notify Central Lincoln when repairs or
modifications have been completed. Extreme caution shall be used when meters are
removed or installed. Depending upon the type of service or meter base, removal
of the meter may not de-energize the customer’s service.
Do not remove meter without confirmation from our meter
department or service office.
Equipment
Instrument transformer (CT and PT)
enclosures, switch-gear, gutters that contain unmetered conductors, and metering
equipment shall have provisions for sealing. Contact Central Lincoln meter
department to remove seals for any future inspections that become necessary.
Central Lincoln will furnish, install (except last item), and
maintain the following equipment:
The customer will be responsible for furnishing, installing, and
maintaining the following equipment beyond the point of delivery:
Available Fault Current
It is the customer's responsibility to
ensure that any fault current interrupting devices installed meet NEC Article
110 requirements regarding interrupting rating. Central Lincoln can provide
information on available fault current at the point of delivery for the original
system as installed. However, system changes can cause the available fault
current to increase. Current-limiting devices are recommended to ensure that
installations continue to meet the intent of NEC Article 110.
Meter Location
You are required to install your
metering equipment in a place that is accessible to Central Lincoln during
normal business hours for meter reading, maintenance, testing, installation and
removal. All locations are subject to approval by a Central Lincoln
representative. If you have questions regarding meter location, call our nearest
service office.
The requirements for properly locating your meter base are:
It must be outside your building - not in breezeways or open
equipment rooms.
It must be located in an area that is not subject to being
fenced or blocked in any way.
It must be located on a structure that is owned by you.
The reasons for these requirements are:
So Central Lincoln’s meter readers can read your meter in a
safe and cost-effective manner.
So Central Lincoln can efficiently maintain your meter.
If you have a fire, we can
disconnect your service.
Meters shall not be installed at any of the following
locations:
Above the first story level or below the first level of a
building. Any exceptions to this rule must have the approval of Central
Lincoln’s Meter Department before electrical installation begins.
On poles owned by Central Lincoln, or other utilities.
In commercial occupancies they do not serve.
Any place safety may be compromised.
General Meter Base Requirements
(Due to the corrosive climate along
the Oregon coast, we recommend that you use a corrosion-resistant meter base
that is state-approved.)
Central Lincoln’s meter base requirements include the following:
Meter bases shall not be jumpered to provide power.
Any meter base containing energized equipment shall be covered
and sealed with a transparent cover plate when a meter is not installed.
All unused openings (knockouts) of the meter base enclosure
shall be closed with plugs (rain-tight, if outside) that are locked tightly in
place from inside the enclosures, before a meter is installed.
Meters shall be installed only in bases which are level,
plumb, and securely fastened to the structure.
Meter bases and enclosures will be acceptable to Central
Lincoln if they have been accepted by Underwriters Laboratories (UL).
Terminals shall be marked with a conductor range for aluminum
or copper conductors. When aluminum conductors are used, the base must be
approved and clearly marked by the manufacturer for that use.
All meter equipment exposed to weather shall be rain-tight
according to the National Electrical Manufacturer’s Association (NEMA) 3R
minimum.
Meter Clearances
The center of the meter base is always
the point of reference. Meter base height shall be a minimum of 5 feet and a
maximum of 6 feet above floor or finished grade.
When a meter base enclosure is recessed in the building wall, a
flush-type base is required. Building siding shall not cover or overlap the
meter base.
Working space in front of metering equipment (including
current transformer enclosures) shall be at least 36 inches wide and 36
inches deep, measured from the front of the enclosure and meters. Plants,
shrubs, and trees shall not be planted in this space. Gas meters and related
piping shall be at least 36 inches horizontally from the center of the meter
base enclosure. (See Figure D-1.)
The center of all meter base enclosures shall be a minimum of 18
inches from adjacent walls, ceilings, or other similar obstructions. All service
equipment, including disconnect switches, shall be a minimum of 18 inches from
the meter’s center. (See Figure D-2.)
If a recessed meter base or meter base cover is installed, a
clearance of 18 inches is required from the center of the meter to the closest
portion of the wall, as shown in Figure D-3.
Multiple Meter Installations
Multiple meter installations shall
comply with the equipment arrangement requirements shown in Figures D-4 and D-5.
Meter Base Labeling
Meter bases shall be permanently
labeled to indicate the part of the premises they service (i.e., unit number).
The customer’s name is not acceptable. Central Lincoln requires engraved
phenolic nameplates or adhesive-type labels at least one-inch high and able to
withstand severe weather conditions. Felt tip pens and label maker tape are not
considered permanent marking. Service will not be established until marking is
complete.
Factory-Built Multiple Meter Panel
Prior to shipment from the factory,
the manufacturer shall submit non-residential multiple meter panel drawings to
the Central Lincoln Meter Department for approval.
On multi-family residential multiple meter panels, the minimum
spacing between base centers (see Figure D-4) shall be 8 inches
horizontally, 8-1/2 inches vertically, and the base center line will be a
minimum of 3 feet and a maximum of 7 feet above the floor or finished grade. On
non-residential multiple panels, the minimum spacing between base centers
(see Figure D-5) shall be 12 inches horizontally, 12 inches vertically, and
the meter will be a minimum of 3 feet and a maximum of 6 feet above the floor or
finished grade. Meters shall be adequately protected from mechanical damage,
and the installation approved by the Central Lincoln Meter Department.
Service Conductors
Meter circuits shall not enter
raceways or enclosures containing unmetered circuits, except in specific
situations approved by Central Lincoln’s meter department.
Customer Load Monitoring
The customer’s load monitoring
equipment shall be installed only on the load side of Central Lincoln’s
metering. No customer equipment shall be allowed inside the meter or instrument
transformer enclosure. The instrument transformer enclosure is not to be used as
a splice box.
Grounding
All meter bases, enclosures and
conduit shall be bonded and grounded in accordance with Articles 230 and 250 of
the latest edition of the NEC. When self-contained meter bases are used, the
neutral conductor shall be connected to the neutral terminal socket.
Current Limiting Fuses
Current limiting fuses to protect the
customer’s electrical system from high fault current shall not be installed in
meter bases, instrument transformer enclosures or Central Lincoln’s distribution
transformers. They may be installed in the customer’s service panel, or in a
separate enclosure between the base and the panel. The separate enclosure may be
on the supply side of the meter bases in multiple meter installations, if the
enclosure has sealing provisions.
SELF-CONTAINED METERING
Single-Phase Services: 200 Amps or Less
A self-contained meter base shall be
installed on all new and remodeled single-phase services (120/240V or
120/208V), where the current-carrying capacity of the service conductors
does not exceed 200 amps, as specified in NEC. (See Fig. D-6-A.)
Underground Non-Residential Meter Bases
Underground 1-phase services, 400 amps
or less, shall use a self-contained meter base. The recommended enclosure is
4-1/4 inches deep, 11 inches wide, and 14 inches high, minimum.
The bending radius of the underground service conductors
requires that off-center knockouts in the bottom of the meter base enclosure
shall be used on all underground services. The center knockout shall not
be used. If the ground lug is not located in the center of the base, the
knockout on the opposite side of the enclosure shall be used.
Single-Phase Services: 201 to 400 Amps
A self-contained 320 ampere meter base
with a 320 class manual bypass (see Figure D-6-B) is required on all new
and remodeled single-phase services (120/240 V) over 200 amps, where the
current carrying capacity of the service entrance conductors does not exceed 400
amps, as specified in NEC. Automatic circuit closures are not acceptable as an
option. Service conductors shall be arranged in the base to avoid interfering
with the meter installation or operation of the manual bypass. Single-phase
services with larger than 7½ HP motors must return a completed
Load Data Sheet.
Single-Phase 120/208 Volt Service
A five terminal meter base is required
on all single-phase 120/208 volt services (see Figure D-6-C). The fifth
terminal shall be in the nine o’clock position, connected to the socket neutral
conductor. This meter is referred to as a network meter.
Three-Phase (0-200 Amps) 120/240 & 120/208
A seven-terminal meter base is
required on all 120/240 delta or 120/208 wye self contained service. The neutral
(grounded conductor) shall be connected or tapped into the third terminal
from the left on the lower terminals (see Figure D-6-D). No bypasses
allowed.
Three-Phase 277-480 Volt - All Loads
All new 480 volt service installations
must be 4-wire 277/480 V. Wye. All 277-480 volt loads shall be metered with
instrument transformers. No self-contained meters are allowed. A
13-terminal meter base is required. The CT enclosure or switchboard must have
space to mount the three metering voltage transformers.
Meter Base/Main Disconnect Combinations
Meter base and circuit breaker
combinations are acceptable for 0-400 amps single-phase, and 0-200 amps
three-phase, provided the meter base section meets Central Lincoln’s manual
bypass and dimensional requirements.
Figure D-6 shows the necessary non-residential meter base types
for specific voltage and amperage ratings.
Sequence of Equipment
All self-contained service equipment
shall be metered ahead of the disconnect switch. Under special conditions
permission may be granted to modify this sequence in group installations of less
than six individual occupancies, provided all equipment ahead of the meter is
sealed by Central Lincoln.
Load Balancing
When 120/208 three-phase transformers
provide single-phase service, it is the customer's responsibility to identify
the conductors and balance the load on the transformer. The customer is
responsible for providing protection for their equipment against single-phasing.
Service Conductors for Self-Contained
Metering
Line-side conductors shall always be
connected to the top terminals of the meter base.
Service conductors shall be arranged in the meter base as to
avoid interfering with the meter installation or operation of the bypass blocks.
The customer is responsible for ensuring that the connection of
service entrance conductors in the meter base shall be inspected and tightened
before the service is energized. Where safety sockets are used, circuit
connecting nuts will also be properly torqued. Meters shall not be installed
unless these connections are tight and wired correctly for the class of service
involved. Meters shall not be installed if conductors place undue strain on the
terminal facilities. Terminals shall be rated for the size of conductor to be
used. Strands shall not be removed to make conductors fit under-sized terminals.
INSTRUMENT TRANSFORMER METERING
Provisions for instrument transformers (also known as current
and voltage transformers) shall be made when the current-carrying capacity of
the service entrance conductors exceeds 400 amps single-phase or 200 amps
three-phase, as determined by NEC.
Customers Responsibility
1. Provide and install an instrument transformer (CT)
enclosure ahead of the main disconnect on the outside of the structure, or in
an approved electrical room. The customer shall install the CT enclosure on
the supply side of the main disconnect, unless otherwise approved by Central
Lincoln’s meter department.
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All CT enclosures require a minimum front clearance of 36
inches. Hinged CT doors shall not block a safety exit while open.
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The top of the CT enclosures shall be a maximum of 8 feet
above the floor or finished grade: the bottom shall be a minimum of 6 inches
above the floor/grade. Enclosures shall not be mounted in crawl spaces,
attics, any confined areas, or mounted to ceilings.
Table 1: CT Enclosure Minimum Dimensions.
|
Service |
Switch Ampacity |
Number of CT’s |
Enclosure |
|
Ht. |
Width |
Depth |
|
1 Phase |
400-800 |
2 |
24" |
24" |
11" |
|
3 Phase |
200-400 |
3 |
36" |
36" |
11" |
|
3 Phase |
401-800 |
3 |
36" |
36" |
11" |
|
3 Phase* |
over 800 |
3 |
* |
* Services over 800 amps require a switchboard designed to
Central Lincoln specifications. Refer to the switchboard metering section on
page 18 for more information. Services from 201-800 amps may be switchboard
designed.
Note: An instrument transformer enclosure shall contain only
the main service conductors. A maximum of four main service conductors may be
served off the load side of each instrument transformer mounting bracket. Call
the meter department if additional conductors are needed. Splicing of service
conductors is not allowed in CT enclosure.
2. Contact the meter department for a list of approved
meter bases. Provide and install the meter base (see Table 1 and Figure D-7)
and the metering circuit conduit.
-
Rigid plastic (schedules 40 or 80), or EMT conduit is
required between the meter base and instrument transformer enclosure and
shall be installed by the customer. Conduit shall be as short as possible,
and shall not exceed 50 feet in length, and not over 180 degrees in bends,
unless specifically approved by Central Lincoln’s meter department. A
pullstring is required in any meter conduit over 25 feet. Flex conduit shall
not be used in meter circuits. Conduit shall not contain condulets or
junction boxes and shall be sized as follows:
-
Single-phase = 1 inch.
-
Three-phase = 1-1/4 inch minimum.
3. Transport Central Lincoln provided instrument
transformers from meter department to project site. Installation of
instrument transformers is the customers responsibility.
Central Lincoln Responsibilities
Central Lincoln is responsible for providing the following:
Instrument transformers.
Meter and test switch.
Metering circuits (wiring).
Note: Customer is responsible for installing instrument
transformers.
Table 2. Bases for instrument-rated meters (with CT’s)
|
Service |
Rated
Current |
Number of
Terminals |
Socket Type (See Fig. D-7) |
|
1-Phase |
401 or greater |
6 |
A |
|
3-Phase |
201 or greater |
13 Wye or Delta |
B |
|
3-Phase* |
201 or greater |
8 Delta |
C |
* Not available for new construction. All new 480 volt
service installations must be 4-wire 277/480 V. Wye.
Switchboard Metering
A switchboard is required for services over 800 amps.
Switchboard metering may be used on services from 201-800 amps at the customer’s
option. (See Figure D-8.)
Three-phase services require a 13-terminal meter base. Outside
switchboard may have the meter base as part of the unit (tests switch required),
or have the meter base attached. Inside switchboard must have the meter base
outside and connected with conduit.
One set of drawings shall be submitted for approval on all
switchboard metering prior to shipment from the manufacturer. Send the drawings
directly to the Central Lincoln meter foreman.
Grounding
All meter bases, enclosures and conduit shall be bonded and
grounded in accordance with Articles 230 and 250 of the latest edition of the
NEC. (See Figure D-9.)
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