Cold sequenced
- Thread starter dicele
- Start date
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paul
Senior Member
- Location
- Snohomish, WA
I believe that is when your meter is on the load side of the disconnect.
COLD SEQUENCE METERING
All new, rewired, altered, or repaired commercial and industrial self-contained meter installations (all installations
other than residential) require the installation of a fusible load-break safety switch with fault current-limiting fuses
ahead of each individual meter. Commercial and industrial installations may be subject to available fault currents up to
100,000 symmetric al RMS amps. Current-limiting fuses shall be selected to limit faults to 10,000 symmetrical RMS
amps at the meter. Fuses considered adequate to protect a meter from excessive fault currents are listed in Section 5,
Tables I through V. A fuse cross-referenc e table is shown in Section 5, Table VI.
Exception 1: A fault current-limiting circuit breaker may be utilized in lieu of a fusible load-break safety switch if
pre-approved by the Company's Electric Meter Engineering Department. The request for approval shall be submitted
in writing, and include a fault-current analysis report sealed and signed by a registered professional engineer. All
requests for approval will be responded to in written form. All calculations shall be based upon the worst-case
transformer percent resistance, percent reactance, and percent impedance values shown in Section 5, Tables I through
Exception 2: Multiple commercial tenant meter sockets are permitted to have a single current-limiting main
disconnect ahead of the common bus to limit fault current to 10,000 amps. Each individual meter shall have a
safety switch or circuit breaker on its line-side to serve as a cold sequence disconnecting means. If a fusible
load-break safety switch is utilized for the main disconnect, the current-limiting fuses shall meet the
requirements in Section 5, Tables I through V. A fault current-limiting circuit breaker may be utilized for the
main disconnect if Company approved in accordance with Exception 1 above.
Exception 3: Single-phase commercial installations up to 320 amps are permitted to be hot sequence provided
all three of the following conditions are met:
(1) Only one meter is served by the overhead service drop or underground service lateral.
(2) The available fault current is below 10,000 amps.
(3) The service voltage is 240 volts or less.
Note: Three-phase meters do not qualify for this exception except as specified in HOT SEQUENCE
METERING, Residential in this Section.
The cold sequence disconnect(s) shall contain provisions for a Company wire seal for the cover and a Company
padlock in the operating handle lock-off position. Wire seals will be used by the Company to secure the enclosure from
unauthorized entry and will allow the customer emergency access to reset breakers or to replace fuses. A Company
padlock will only be used to lock disconnects in the off position for services that are shut off.
The cold sequence disconnect(s) shall be furnished, owned, and maintained by the customer.
Tables VII through IX in Section 5 can be used to determine if the available fault current at a single-phase
electric meter socket is less than 10,000 amperes based on a specific transformer size and service conductor size
and length.
This was copied from Xcel Energys standards book, available online @ www.xcelenergy.com
Hope it helps,
Jim
All new, rewired, altered, or repaired commercial and industrial self-contained meter installations (all installations
other than residential) require the installation of a fusible load-break safety switch with fault current-limiting fuses
ahead of each individual meter. Commercial and industrial installations may be subject to available fault currents up to
100,000 symmetric al RMS amps. Current-limiting fuses shall be selected to limit faults to 10,000 symmetrical RMS
amps at the meter. Fuses considered adequate to protect a meter from excessive fault currents are listed in Section 5,
Tables I through V. A fuse cross-referenc e table is shown in Section 5, Table VI.
Exception 1: A fault current-limiting circuit breaker may be utilized in lieu of a fusible load-break safety switch if
pre-approved by the Company's Electric Meter Engineering Department. The request for approval shall be submitted
in writing, and include a fault-current analysis report sealed and signed by a registered professional engineer. All
requests for approval will be responded to in written form. All calculations shall be based upon the worst-case
transformer percent resistance, percent reactance, and percent impedance values shown in Section 5, Tables I through
Exception 2: Multiple commercial tenant meter sockets are permitted to have a single current-limiting main
disconnect ahead of the common bus to limit fault current to 10,000 amps. Each individual meter shall have a
safety switch or circuit breaker on its line-side to serve as a cold sequence disconnecting means. If a fusible
load-break safety switch is utilized for the main disconnect, the current-limiting fuses shall meet the
requirements in Section 5, Tables I through V. A fault current-limiting circuit breaker may be utilized for the
main disconnect if Company approved in accordance with Exception 1 above.
Exception 3: Single-phase commercial installations up to 320 amps are permitted to be hot sequence provided
all three of the following conditions are met:
(1) Only one meter is served by the overhead service drop or underground service lateral.
(2) The available fault current is below 10,000 amps.
(3) The service voltage is 240 volts or less.
Note: Three-phase meters do not qualify for this exception except as specified in HOT SEQUENCE
METERING, Residential in this Section.
The cold sequence disconnect(s) shall contain provisions for a Company wire seal for the cover and a Company
padlock in the operating handle lock-off position. Wire seals will be used by the Company to secure the enclosure from
unauthorized entry and will allow the customer emergency access to reset breakers or to replace fuses. A Company
padlock will only be used to lock disconnects in the off position for services that are shut off.
The cold sequence disconnect(s) shall be furnished, owned, and maintained by the customer.
Tables VII through IX in Section 5 can be used to determine if the available fault current at a single-phase
electric meter socket is less than 10,000 amperes based on a specific transformer size and service conductor size
and length.
This was copied from Xcel Energys standards book, available online @ www.xcelenergy.com
Hope it helps,
Jim
- Status