AC/DC Power and Battery Installation Requirements
AC/DC Power and Batteries – General Requirements
Due to certain regulatory and non-regulatory conditions, these listed guidelines shall apply when the installation environment is in a regulated workspace. For the non-regulated/non-utility environment, refer to ATT-TP-76301.
The Installation Supplier can reference the specific installation requirements for battery, return, and bus bar hardware connections that are listed in AT&T Power Drawing – ATT-P-05100-E.
The Installation Supplier shall verify (with a multi-meter) the absence of voltage on the battery and battery return leads before connecting the leads. That is, when two conducting parts are to be landed, there shall be less than or equal to 0.05V between them.
The Installation Supplier shall verify (with a clamp-on ammeter) the absence of current for each power lead to be removed.
Power equipment and bus bars shall be protected any time there is installation activity in the immediate vicinity. See Section B.
If electronic BDFB/SPDU load monitoring is not available at the site, the BDFB/SPDU Load Demand Worksheet (LDW) shall be used. See Section E of ATT-TP-76300. Instructions and worksheets are also available on the Extranet Web Site if needed.
The record of the installation for a new BDFB/SPDU shall be completed by the power installation vendor and sent to the AT&T Power Engineer and cluster vendor within five working days of the Installation Complete Date. The New BDFB Worksheet form is available on the Extranet Web Site and FileNet.
Per NEC Article 110-26, a minimum of 48 inches of clearance shall be maintained when placing new panels and serving equipment with nominal voltages greater than 150v (AC or DC). This does not include any side panels where the equipment is built for no access.
AC/DC Power and Batteries – Removal of DC Fuses or Opening DC Circuit Breakers
Unless stated otherwise in the MOP, the Supplier shall not remove a fuse or open a circuit breaker serving energized equipment. The AT&T Representative is responsible for opening the circuit on energized equipment.
The Installation Supplier shall ensure that all circuit breakers that are spare, unassigned, or reserved for future equipment are in the “Off” position.
AC/DC Power and Batteries – DC Circuit Protection Devices
Fuses and circuit breakers shall be of the type and capacity as indicated in the job documentation. Under no circumstances shall circuit protection devices (fuses or circuit breakers) be placed in parallel in order to increase circuit capacity.
Only approved GMT style and Telpower® or Telcom® -type fuses shall be used on DC circuits unless another type of fuse is specified in the applicable AT&T Equipment or Power Drawing.
The Installation Supplier shall install all circuit protection devices to make the equipment operational only at the direction of the AT&T Representative or as authorized in the MOP.
Dummy fuses shall be installed at all open faced and GMT type vacant fuse positions.
Cartridge and knife type fuses shall be coated with a thin film of NO-OX-ID “A” anti-corrosive compound.
Blade type fuse position contacts shall be coated with a thin film of NO-OX-ID “A” anticorrosive compound prior to fuse installation (on contact surfaces only).
The use of any fuse reducer shall require the authorization of the AT&T Power Equipment Engineer.
AC/DC Power and Batteries – DC Circuit Protection Devices
Spare circuit protection devices shall be placed in a designated location or turned over to the AT&T Representative at job completion if a spare fuse holder is not provided.
On BDFBs and power boards, all local alarm wiring for associated fuses/circuit breakers shall be tested in accordance with Section E of ATT-TP-76300.
Connecting hardware shall be installed on all BDFB/SPDU fuse posts.
Secondary power distribution cable connections to BDFB/SPDU fuse posts shall be up to the maximum power cable size (based on circuit ampacity and voltage drop requirements) allowed by the Fuse Disconnect/BDFB Manufacturer.
a. Secondary power distribution cabling to a 1/4-20 connection stud on a 15800 (TPS) or other type Fuse Disconnect shall be up to ( ) #2AWG.
b. Power cabling to a 5/16-18 connection stud on a TP158HC (TPL) or other type Fuse Disconnect shall be up to ( ) 2/0AWG.
Circuit Protection devices shall not be installed or activated on unterminated leads (power wire/cable).
The largest circuit protection device to be used in a BDFB/SPDU shall be no larger than 150 Amps.
The Installation Supplier shall verify that all electrical contact surfaces are not damaged.
AC/DC Power and Batteries – Battery Post
The Installation Supplier shall refer to the job documentation and cell manufacturer‘s documentation for specific requirements and precautions for cleaning and treating cell posts. If the cell manufacturer’s recommended procedures for cell post cleaning and preparation differ from those specified in this section, then the Installation Supplier shall contact the AT&T Maintenance Engineer for direction.
All contact surfaces of flooded lead acid and VRLA battery posts and contact areas of intercell connectors shall be cleaned and coated with a thin film of NO-OX-ID “A” anticorrosive compound.
All cell post connections shall be made with the proper tools and shall be tightened to the manufacturer’s torque requirements.
When lead-plated details and/or details with elongated holes are used, flat lead-plated or stainless steel washers shall be used under the nut and under the bolt head.
Requirements for connector terminations to the lead battery posts of lead acid-type batteries or battery plates are in Section K, ATT-TP-76300.
Lead coated connectors shall be used when connecting to lead acid-type batteries or battery post terminal adapter plates.
AC/DC Power and Batteries – Battery Post
The maximum shiner (space) shall be no greater than 1/16 inch between the end of the barrel and the cable insulation butt. If the shiner is greater than 1/16 inch and does not exceed ¼ inch, the space shall be covered with clear heat shrink tubing. Where the shiner exceeds ¼ inch, the connection shall be remade. If battery and battery return cables have manufacturer applied clear heat shrink tubing, it is permissible for the connector inspection window and compression crimps to be covered.
On new battery string installations, all nuts, bolts and washers shall be stainless steel, unless specified otherwise by the manufacturer. Stainless steel (316 or better grade) is required, and the flat washer shall be 1/8 inch thick. The smooth (rounded) side of the flat washer shall be placed against and not overhang the battery strap or connector lug. Where lock washers are provided by the battery manufacturer, they shall be assembled on top of the flat washer as shown in the ATT-P-05100-E drawing.
The threaded portion of bolts on intercell connectors shall not be installed to have exposed threads past the nut more than the equivalent diameter of the bolt.
AC/DC Power and Batteries – DC Bus Bars – Assembly
The Installation Supplier shall use zinc-chromium plated SAE J429 ASTM B117 & B633 specifications or ASTM B99 silicon bronze finished bus bar joint, fastening and support bolts, nuts, washers, etc. as listed on the Minor Material List. The hardware shall be American National Coarse with a Class #2 Fit.
Bus bar runs shall be supported on a maximum of 6 feet 0 inch centers. Each length between joints shall be supported on both sides of a mechanical splice.
Bus bar runs supported by ceiling inserts, threaded rod and/or auxiliary framing channels shall be braced, both side and lengthwise, according to AT&T seismic requirements.
Except for the auxiliary framing bar supporting the red insulator, bus bar runs shall be installed at least one foot from metal pipes, cable racks, and auxiliary framing channels, etc., unless approved by the AT&T Power Engineer. In no case shall this distance be less than three inches.
Bus bars shall be a minimum of 7’3” above finished floor.
The bus bar shall be insulated from all supporting ironwork with approved insulators.
Exposed bus bar splice plates with plant voltage potential, located outside the power plant environment, (e.g. above or below secondary power distribution frames, cable rack, auxiliary framing, etc.,) shall be protected, in order of preference:
a. With non-combustible covers (V-1 or better rating), or
b. Have each bus bar and its associated cable connectors wrapped with two half-lapped layers of plastic insulating tape.
AC/DC Power and Batteries – DC Bus Bars – Connecting Bus Bars Together
Existing aluminum bus bars or details shall not be connected directly to heat producing devices. Examples are:
a. Circuit breakers
b. Fuse terminals
c. Switch terminals
d. End cells
Aluminum bus bars shall not be tapped for fastening terminal lugs or for fastening bar to bar. Use through-bolts or clamp joints.
Only American Standard Unified Course (UNC) Grade 5 threads and hardware shall be used on all external power plant and bus bar connections (internal manufacturer power plant connections may be metric as long as there are no requirements for field installation interaction).
High spots, sharp edges and burrs shall be removed from all electrical contact areas, before assembly, to maximize continuity. Contact surfaces shall be flat.
AC/DC Power and Batteries – DC Bus Bars – Connecting Bus Bars Together
Plated contact surfaces shall be cleaned without using abrasives coated with a thin film of NO-OX-ID “A” anti-corrosive compound and then assembled in a timely manner.
All non-plated contact surfaces shall be cleaned with a fine abrasive material coated with a thin film of NO-OX-ID “A” anti-corrosive compound and then assembled in a timely manner.
The overlap at a bus bar joint shall be no less than the width of the bus bar.
For through-bolt connections on bus bars, flat washers shall be used under the nut and under the bolt head. In addition, a lock-washer shall be used under the nut. (See AT&T Drawing ATT-P-05100-E for assembly details.)
AC/DC Power and Batteries – DC Bus Bars – Bus Bar Clamps
Clamps that have a bus bar contact surface concave in shape are defective and shall not be used.
Bus bar clamp bolts shall be equipped with self-locking pal nuts. Non-self-locking nuts shall be torqued per the manufacturer’s specifications before applying a pal nut. The pal nut shall be applied with the smooth (flat) side in, open side out, run up to the regular nut, tightened and taken up only one quarter turn with an insulated wrench. On larger clamps, lock nuts may be provided instead of pal nuts. The lock nuts shall be tightened until tension is snug against the regular nut.
AC/DC Power and Batteries – DC Bus Bars – Taping
Two overlapping wraps of plastic electrical insulating tape, (e.g., Scotch 33 or Scotch 88) (when required) shall be applied when taping bus bars with battery potential.
The Installation Supplier shall tape the portion of the battery return bar in close proximity to live exposed terminals, studs, etc. In power rooms or in power board lineups containing power exclusively, taping is not required.
Bus bars, studs, nuts and details having 150 volts or more to ground shall be taped with two layers of friction tape, unless protected by enclosures or barriers.
Power panels and power boards having 150 volts or less shall have exposed details taped when located in open type frames, racks, boards and bays. In power rooms or in power board lineups containing power exclusively, taping is not required.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – General
Batteries shall not be unpacked until the battery stand installation is complete and the Installation Supplier is ready to install the batteries.
The Installation Supplier shall not place cells of different manufacturers in the same string. Unlike strings, however, may be placed in parallel. KS20472 List 1 round cells can be replaced by KS20472 List 1S cells.
When cells in a string are replaced, the replacing cells shall have the same ampere-hour capacity, the same number of plates and shall have the same manufacturer. KS20472 List 1 round cells can be replaced by KS20472 List 1S cells.
Battery cells shall not be lifted or moved using the intercell connectors, cell posts or covers; with the exception of the KS20472 round cell battery which is designed to be lifted by the jar cover lip.
The battery marked as the pilot cell shall have a thermometer installed.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Cautions
While batteries are being charged, the Installation Supplier shall post temporary warning signs in conspicuous locations near the batteries as follows:
WARNING: BATTERY GASES ARE FLAMMABLE. NO SPARKS OR OPEN FLAME NEAR CELLS.
While batteries are being charged, the following precautions shall be observed:
a. Provide maximum ventilation (at least 2 air changes per hour).
b. Before charging, allow the cell to stand at least 1/2 hour on open circuit or on float voltage.
c. Install explosion vent caps before charging
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Shipping Batteries for Removal or Reuse
When batteries are removed for non-reuse, procedures described in ATT-TP-76300, Section V shall be followed.
Batteries scheduled for reuse shall be inspected by the METS/ATS (or their designees) to determine battery string condition; pressure testing as required (before and/or after redeployment); estimated time for relocation; and pre-determination of expected length of a boost charge where required for input to the engineering cost estimate. The batteries shall be prepared for shipment as follows:
a) All cells shall be individually marked with the original string cell position number.
b) All battery records shall be packed with the batteries in a plastic sleeve, taped to cell 1 in each string. Where battery records are not available, a written statement regarding this shall be placed in the plastic sleeve. The date and time the string is removed from float shall also be placed in the plastic sleeve.
c) Batteries relocated as a complete string shall be reinstalled in the same order as placed in the original installation.
d) If a string is removed and cells are shipped to different locations for reuse, a copy of the complete battery string record shall be included with each shipment.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Shipping Batteries for Removal or Reuse (Continued)
e) Miscellaneous battery items such as spark arrestors and thermometers shall be packed and stay with the cell in which they were originally installed.
f) Shipping plugs and filling tube caps shall be firmly installed to prevent electrolyte spillage.
g) Battery terminals shall be protected against short circuits with tape, caps or protective packaging.
h) Battery intercell connectors and associated hardware shall be inspected and replaced as necessary; non-stainless steel hardware shall be replaced regardless of condition.
i) Perform a complete review of batteries at new location(s) as required in ATT TP 76300 Section M, Paragraph 3.4.5.
j) Pressure testing shall be required where specified by the ATT Equipment Engineer in the TEO, METS/ATS or GNFO based on the condition of the batteries prior to shipment and/or when received at the installation site. Jar pressure tests when taken before relocation shall be compared to pressure testing results after the battery relocation and installation. Jar pressure testing at a minimum shall always be done after the batteries are installed on the battery rack.
k) After relocation and installation, the METS/ATS shall verify estimated charge testing requirements for the re-used batteries are sufficient for the condition of the batteries. If additional charging is required over the initial job estimate, the METS/ATS will notify the ATT Implementation Engineering and the Installation Supplier. Boost charging where specified by METS/ATS shall at a minimum meet or exceed manufacturer requirements to maintain the battery warranty.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Cell Unpacking, Cleaning, and Inspection
Flooded battery cells shall remain in their protective packaging or be protected from damage until commencement of battery installation.
All cells shall be cleaned and neutralized thoroughly as soon as practical after they arrive on the job. Use a wet cloth in a 5% – 10% baking soda or soda ash solution, squeeze out sufficiently, and wipe thoroughly to neutralize cell top and sides. Ensure that posts, post holes and post seals are thoroughly cleaned.
After neutralization has been completed, the Installation Supplier shall remove salts and residue with water, wet cloth and frequent rinsing. Batteries and/or jars shall be wiped clean until dry to be sure all soda residues have been removed.
Solvents, mineral spirits, commercial detergents, ammonia, or other cleaning compounds or oils, waxes or polishes shall never be applied to the cell jar or lid. When such information is not provided in the job documentation (e.g., cell manufacturer’s documentation) only water and baking soda or soda ash may be used.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Cell Unpacking, Cleaning, and Inspection
The Installation Supplier shall make a visual inspection of all batteries shipped to the job site (prior to installation) to identify any physical damage, defects or problems that may prevent their proper installation, maintenance and/or operation.
The Installation Supplier shall inspect for the following defects:
• Breaks in the jar to cover seal.
• Crooked posts.
• Plates improperly supported on the bottom bridge.
• Loose paste material between the jar wall and interior.
• Bent or broken internal parts.
• Cracked jar or cover.
• Scratched, gouged, or chipped jar or cover. Indentations of more than 1/64 of an inch should be reported.
• Hairline cracks around the cell and post.
• Small dots on the post or early signs of post porosity.
• Uneven gaps or flaws in the cover.
• Crystals on plates.
• Low (touching plates) or high (at or above upper level mark) electrolyte level.
• Presence of sprues (raised areas) on the jar
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Cell Unpacking, Cleaning, and Inspection
When uncrating cells, the Installation Supplier shall check for stains or discoloration in the packing material to locate damaged or defective cells.
The Installation Supplier shall install explosion proof vents when cells are first unpacked.
In all geographic areas, batteries awaiting installation shall be secured (strapped together in groups of four or more with non-metallic straps).
Unpacked batteries awaiting installation shall not be covered with a tarp.
Upon installation of a new battery string, the Installation Supplier shall inspect and verify that all voltage-matching stickers are of like color prior to their initial charge. The only exception being round cell technology, which does not supply the stickers. In the event that the entire string does not have like colored voltage-matching stickers the Installation Supplier shall notify the AT&T Power Equipment Engineer for direction before proceeding.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Pressure Testing
The following testing requirements apply only when ordered by the AT&T Equipment Engineer, or if any battery leakage is found in any of the cells during unpacking:
a. The Installation Supplier shall pressure test all cells. The cells shall be pressure tested after placement onto the stand to assure that they were not damaged during placement. The Installation Supplier may choose to perform an additional pressure test prior to placing cells on the rack (to avoid placing a “leaker”). This, however, does not replace the “on the rack” test.
b. Cells, posts and cover seals shall withstand a pressure of 1/2 pound per square inch for one minute without any noticeable loss in pressure. Do not over pressurize the cells.
c. Document the results of the pressure test on the Pressure Test Record (ATT-TP-76300, Figure M-1).
Pressure Test Records shall be turned over to the AT&T Equipment Engineer at the completion of the job.
The Installation Supplier shall notify the AT&T Equipment Engineer, as soon as practical, if a cell does not pass pressure tests.
Cells that do not pass the pressure test shall not be connected until the cell has been fixed and passed a retest, or is replaced.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Electrolyte Spills
All spills shall be contained and reported to:
• AT&T Environmental Health & Safety at 1-800 KNOW EHS or,
• For Legacy-B locations, 1-888-330-CRES.
Refer to Section V, ATT-TP-76300 for additional requirements concerning Electrolyte spills.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Battery Water
Prior to initial charging, if the electrolyte level is below the bottom fill line, the Installation Supplier shall adjust the electrolyte level to the bottom fill line. No adjustment shall be made if the electrolyte level is above the bottom fill line.
AC/DC Power and Batteries – Flooded Lead-Acid Storage Batteries – Battery Preparation
The Installation Supplier shall notify the AT&T Equipment Engineer if the electrolyte is above the upper level line when the cells are received at the job site. The Installation Supplier shall NOT remove excess electrolyte for any reason.
A Storage Battery Charge Report (see Figure M-2) shall be maintained on each battery throughout the installing and charging phases of battery installation. A completed copy of the Storage Battery Charge Report shall be provided to the AT&T Representative at job completion.
The Installation Supplier shall check the installed batteries for the presence of crystals. If crystals or other defects are detected, notify the AT&T Equipment Engineer. The Installation Supplier shall note the presence or absence of crystals on the Storage Battery Charge Report.
AC/DC Power and Batteries – Battery Racks – General
Battery racks shall be positioned, assembled, aligned, grounded, designated and installed as specified in the job documentation, ATT-TP-76300, and the rack manufacturer‘s documentation.
For personnel protection, creating sparks while working with batteries shall be avoided. To avoid Electrostatic Discharge (ESD), the Installation Supplier shall perform one of the following steps prior to beginning each work operation involving battery work:
a. Firmly touch a grounded metal rack/object or battery termination plate near the return (grounded) end of the battery for the removal of static electricity.
b. If the battery stand is equipped with an ESD ground termination, an ESD wrist/ankle strap may be used for self-discharge. However, it is not the intent to require the technician to wear the device while working on the batteries, except during charging.
AC/DC Power and Batteries – Battery Racks – General
The following are minimum clearances between a battery rack and other battery racks, equipment, rigid spill containment and non-movable obstructions. The Installation Supplier shall notify the AT&T Equipment Engineer if the minimum requirements cannot be met to determine resolution.
a. Adjacent or parallel racks – 36 inches.
b. Double row rack and a wall – 36 inches.
c. Equipment or bays – 36 inches.
d. Walls – 36 inches. This applies to the end of a rack where the length of the rack exceeds 72 inches. A single row rack parallel to a wall shall be a minimum of 8 inches from the wall. The clearance of a rack shall be a minimum of 8 inches from another structure at one end of the rack (the other end requires 36 inches). At no time shall fire aisles be blocked.
AC/DC Power and Batteries – Battery Racks – General
On a two-tier, two-row, two-string, rectangular, flooded lead-acid battery rack each of the battery strings shall have cells 1 through 12 on the bottom tier and 13 through 24 on the top tier.
In seismic zones 3 and above, cell separators shall be installed between battery cells. Manufacturer supplied battery container support cradles may be used instead of cell separators if they minimize battery movement.
In seismic zones 2 and below, cell separators or container support cradles shall be installed between battery cells if shipped by the battery manufacturer.
Only material that meets an oxygen index of 28 or better shall be used as cell separators. (Styrofoam packing material shall not be used as separators.)
When tie rods are required for seismic protection on a battery stand installation, it is permissible to double nut the battery stand tie rod on both ends.
Battery cells shall not touch each other or adjacent framework.
a. The spacing between the cells in a row shall be 3/8” to 5/8”.
b. The spacing between the rows of cells shall be greater than 3/4”.
c. Side and end-rail clearance to the battery jar shall be 1/32” to 1/8”. On installation, PVC jars should be set up with the maximum clearance to allow for jar growth.
AC/DC Power and Batteries – Battery Racks – Battery Cabling (Unfused)
Size 4/0 flexible type power cable shall be the standard size and type to be used on all cells through 1900 AH. A cable size of 350 kcmil, flexible type power wire shall be used on all cells over 1900 AH.
Cables between the battery posts and battery bus bar shall be installed as shown in ATT-TP-76300, Table M-3.
Cable runs, from bus bar drop plates to cell posts shall have sufficient slack to allow 6 inches of movement.
The Installation Supplier shall install the same quantity of equal length inter-tier and equal length inter-shelf conductors.
AC/DC Power and Batteries – Charging Storage Batteries – Charging
Before charging is started, the Installation Supplier shall designate the cell with the lowest specific gravity as the Pilot Cell (a.k.a Temperature Reference Cell). The Pilot Cell shall be located on the lower shelf of the stand. Do not place the Pilot Cell on the end of a stand, near a window, or near a heating/cooling vent.
When more than one string is charged in parallel, the Installation Supplier shall select a separate Pilot Cell for each string.
The Installation Supplier shall record the Pilot Cell number in the appropriate box on the Storage Battery Charge Report (Figure M-2). Indicate number of strings charged in parallel and voltage regulation employed.
The Installation Supplier shall insert a thermometer in the Pilot Cell so the temperature reading can be taken without touching the thermometer. The Pilot Cell is used for the purpose of temperature measurement for the hours of charge.
The Installation Supplier shall provide its own portable battery charger with a protective fuse device.
Before installation, batteries shall be charged in accordance with manufacturer’s recommendations.
When using a voltage regulated charger delivering at least 12 amps, the Installation Supplier shall monitor the initial charge.
AC/DC Power and Batteries – Charging Storage Batteries – Charging
Just before the start of initial charge, the Installation Supplier shall measure the cell temperature of the Pilot cell and determine the total length of initial charge requirement by referring to corresponding Cell Temperature column and Time on Open Circuit column of ATT-TP-76300, Table M-2. The required time on charge begins at the time that the voltage and current have reached steady state operation.
The Installation Supplier shall ensure that adequate ventilation is present to prevent the hydrogen concentration from reaching the 1 percent level at any time during the charging process. Warning signs shall be placed near the charge area. For information regarding ventilation requirements, refer to Section 6 of ATT-TP-76400.
Explosion proof vent caps and shipping plugs (for the electrolyte draw-off tubes) shall be firmly in place on each cell during cell charging activities.
Before performing any work functions, the Installation Supplier shall touch any bare metal grounded part of the battery rack to avoid ESD to the batteries.
AC/DC Power and Batteries – Charging Storage Batteries – Charging Records
The Installation Supplier shall complete the Storage Battery Charge Report (ATT-TP-76300, Figure M-2) for each battery string. Document the voltage, specific gravity and temperature of each cell at the following intervals.
a. Prior to start of initial charge (indicated in Initial Charge section of ATT-TP-76300, Figure M-2)
b. At end of charge, prior to turn-down to float
c. 72 hours after end of initial charge
The Installation Supplier shall document (on the Pilot Cell Charge Report, ATT-TP-76300, Figure M-3) the time, charge current, voltage and temperature of the pilot cell, at the following intervals:
a. At the start of charge.
b. Once each hour for the first eight hours of charge.
c. Three times a day after the first eight hours of charge.
d. Just before charging is stopped or temporarily discontinued. Reference the manufacturer’s documentation to establish the recommended procedure to determine and record full charge.
e. When charging is restarted (if initial charge is interrupted) and the charge current is stable.
All Storage Battery Charge Reports shall be placed in the central office retained battery records book or separately turned over to the AT&T Representative. A copy shall be placed in the job folder.
AC/DC Power and Batteries – Charging Storage Batteries – Electrolyte Level
While batteries are on initial charge, the electrolyte level may rise above the maximum level line. If it should become necessary to remove electrolyte to prevent overflow, the Installation Supplier shall make note of removals on the battery initial charge records. Retain electrolyte for possible reuse at the cell level.
Electrolyte not reused shall be disposed of in accordance with Section V, Hazardous Material and Waste Management of the ATT-TP-76300.
After the initial charge, distilled water shall be added to bring the electrolyte midway between the lower and upper level lines. If the electrolyte level exceeds the high mark, the Installation Supplier shall note the high level on the initial Storage Battery Charge Report in the comment section, but shall not make any adjustment in the electrolyte.
AC/DC Power and Batteries – Charging Storage Batteries – End of Initial Charge Crystal Identification
Before stopping the initial charge, the Installation Supplier shall record the following for each cell on the Storage Battery Charge Report:
a. Voltage
b. Specific gravity
c. Electrolyte temperature
After a satisfactory initial charge, there shall be no crystals or discoloration present on the plates when examined with a flashlight.
Cells that is not free of crystals after the initial charge may contain an internal short. If some cells still have crystals after the initial charge, it is recommended that the battery string be continued on boost charge at 2.5 to 2.55 volts for a total charge time not to exceed 250 hours for both charges. If charging fails to clear the crystals within 250 hours, the cells shall be referred to the AT&T Equipment Engineer for investigation and/or replacement.
AC/DC Power and Batteries – Charging Storage Batteries – Turnover
The Installation Supplier shall ensure that the full-charge specific gravity of each cell meets the manufacturer’s documentation and does not vary by more than 0.015 (15 points) per cell.
On the installation of new battery strings, the power plant float voltage shall be upgraded to 52.80 volts if not already at that float setting
Cell voltage shall have a measurement between 2.15 and 2.25 volts for the recommended 52.80 Power Plant Voltage; or between 2.12 and 2.22 volts for a 52.08 Power Plant Voltage.
All charged strings shall remain on continuous uninterrupted float voltage of 2.20 (52.80 Power Plant Voltage) or 2.17 (52.08 Power Plant Voltage) volts per cell until placed in service.
AC/DC Power and Batteries – Charging Storage Batteries – Valve Regulated Cells
The manufacturer’s installation instructions and forms shall be utilized for installation of valve regulated cells.
The Installation Supplier shall record individual battery jar and strap conductance values before battery charge.
For initial charge, temperature compensated chargers or current limited chargers shall be used to insure that thermal runaway does not occur.
For float operation, temperature compensated controllers shall be used to insure that thermal runaway does not occur.
Valve regulated lead-acid (VRLA) cells shall have a float voltage measured at 2.25 volts, plus or minus 0.05 volt, provided this value is within manufacturer’s specifications.
A VRLA Battery String shall contain 24 cells with a nominal 54.00 VDC Float Voltage.
For CO or Type 1, 2, and 3 Nodes applications, a Battery Monitor or Float Current Monitor shall be provided for all VRLA battery Strings.
AC/DC Power and Batteries – Charging Storage Batteries – Valve Regulated Cells
Before any VRLA battery string can be accepted, the resistance or conductance of all cells and inter-cell connectors shall be read and recorded by the supplier’s installer. This record becomes part of the battery records turned over to the AT&T Representative and must remain with the battery string. These records are used as a baseline for future readings. The test shall meet the following requirement.
• Supplier shall use a test set approved by AT&T Maintenance Engineering
• Each cell and intercell connector shall be measured.
• No reading (conductance or intercell connector resistance) shall be more than
• 20% above or below the average for the string. Individual intercell connector measurements above 35 micro-ohms shall be investigated to assure proper torque, cleanliness, etc.
• The test set manufacturer’s form shall be used as a paper record.
• A paper copy and disk or CD of the test results will be left on site.
• The CD or computer diskette shall also have a spreadsheet and a graph of the cell conductance and intercell connector measurements.
After string has settled at proper float voltage, the Float Current shall be recorded and preserved as a baseline.
VRLA battery strings shall be equipped with individual string disconnects for Type 1, 2, and 3 Nodes, or customer premises applications.
AC/DC Power and Batteries – Charging Storage Batteries – Flooded Nickel Cadmium
The manufacturer recommendations and forms shall be utilized for the installation of NiCad cells.
The Installation Supplier shall perform and record an Open Circuit Voltage (OCV) for each cell before installation. Any cell with less than 1.10 volts shall be replaced.
The NiCad battery strings for Central Office applications contain 38 (1.43V) cells that shall have a string float voltage measured at 54.4V for optimum performance. The float voltage can be reduced to 1.42 volts per cell (54.0 string float) if there is an adjustment issue with high voltage alarms with high voltage alarms.
The higher than normal 54.4V float voltage requires that a power plant be entirely supported by NiCad batteries. Strings of flooded lead acid batteries or VRLA batteries shall not be mixed with NiCad battery strings.
Recommended alarm points for the 54.4 float are: Very High Voltage – 56.0V; High Voltage – 55.5V; Low Voltage – 52.0V; Very Low Voltage – 48.0v.
Saft® NiCad NCX-125 Battery Drain Table end voltage is 1.10V per cell; 42V for a 38 cell string after delivering up to a constant 16A current discharge for 4 hours when new. Load bank testing shall be performed at 35.2A for a Saft NCX-125 battery string.
Battery racks that house the NiCad batteries shall have sliding shelves allowing adequate working space, and shall meet the seismic rating for the geographic area.
AC/DC Power and Batteries – Charging Storage Batteries – Flooded Nickel Cadmium
Battery cabling between the battery strings and the bay collection bars shall be continuous; the use of Anderson or Anderson-style quick-connectors is prohibited.
Size 2AWG flex cable shall be used to connect up to 125AH NiCad battery strings shelves to the rack battery and return bus bars (collection bars). The use of the 2AWG flex cable allows easy movement of the shelves for battery servicing. For this application, gray cotton braid flex-cable is preferred over rubber insulation.
Battery collection bars shall be installed at the top of the NiCad bay(s).
Tin plated copper lugs without inspection holes and nickel plated steel hardware shall be used for NiCad battery connections.
NiCad battery hardware shall be Saft® supplied as standard metric threads are not compatible with the Saft® NiCad battery connections.
NiCad battery connections shall be torqued to 50 inch-pounds.
Saft® NOX-Rust corrosion inhibitor shall be used on all external battery connections.
AC/DC Power and Batteries – Charging Storage Batteries – Flooded Nickel Cadmium
NiCad batteries contain a corrosive alkaline electrolyte solution that shall be neutralized with a special NiCad spill kit (which is labeled in bright orange). Spill kits for flooded lead acid batteries do not contain the correct neutralizing absorbent for NiCad batteries, and the lead acid battery safety equipment shall not be used when cleaning up a NiCad electrolyte spill due to the potential of a dangerous chemical reaction.
NiCad batteries can release hydrogen gas, and the same safety precautions regarding gassing and explosion hazard apply to NiCad as flooded lead acid battery installations.
NiCad batteries shall use constant voltage charging to maintain float voltage. Temperature compensated voltage control used with VRLA application is not recommended.
High float current on a NiCad battery string is an indication there is a maintenance issue or the battery is reaching end-of-life.
NiCad batteries shall only be recycled through the manufacturer.
Additional details regarding NiCad batteries can be found in AT&T Power Drawing – ATT-P- 05330-E.
AC/DC Power and Batteries – Charging Storage Batteries – Alternative Battery Technologies
All new battery technology shall be installed with charge records, maintained and serviced per the manufacturer’s documentation.
AC/DC Power and Batteries – Flooded Lead-Acid String Transitions – General
Prior to and during battery transition work, air flow in the battery area shall be at least two air changes per hour to eliminate the buildup of hydrogen gas.
The Installation Supplier shall ensure that temporary wiring for transition batteries is never less than two 4/0 or one 500 kcmil for 1680 AH and smaller or two 500 kcmil for strings larger than 1680 AH.
The Installation Supplier shall ensure that the battery string to be transitioned has been on a stable float charge for at least 48 – 72 hours so that hydrogen gas release is minimal. Only one string shall be taken off line at a time. When opening a string, the installation supplier shall cover cable ends by taping on a heat shrink cap after removing bolt assemblies.
When necessary, the transition string voltage shall be raised to adjust voltage differences to 0.05 volts or less. The AT&T Representative must approve any decision to lower the plant voltage for a battery transition. The plant voltage shall never be lowered more than 2.0 volts from the normal float voltage for a -48 volt plant.
In all cases, the plant voltage shall be kept within the operating limits of the equipment served by the battery plant.
AC/DC Power and Batteries – AC Power in the DC Operating (Regulated) Environment – AC Panels
Per the NEC, all newly placed AC panels and serving equipment with AC input voltages 150v AC or greater shall maintain a minimum working clearance of 48 inches. This does not include the rear or side(s) when the equipment is built for no access.
Circuit Breaker additions to existing AC Panels (PSC/PDSC) shall be validated for the existence of available capacity. Additional distribution circuit breakers shall not be added to the (PSC/PDSC) AC Panels where measured demand exceeds 80% of the primary supply circuit breaker. Installation Suppliers shall notify the responsible AT&T representative where the 80% levels have been met or exceeded.
AC/DC Power and Batteries – AC Power in the DC Operating (Regulated) Environment – AC Cabling
All AC conductors shall be enclosed in a metal conduit, metal raceway or metal trough.
All final AC equipment connections, or conduit transitions from walls or columns in Seismic Zones 3 & 4, with Jacketed Metallic Clad (JMC) flex (Seal-Tite® SA, or Liquidtight® LA rated UL 94 V-0) shall not exceed three feet.
In High Seismic areas where JMC is used between the wall or column and conduit supported by auxiliary framing, the Installation Supplier shall install the JMC with a minimum of six inches of play.
Final AC lighting fixture connections with Jacketed Metallic Clad (JMC) flex (Seal-Tite® SA or Liquidtight® LA rated UL 94 V-0) shall not exceed six feet.
Jacketed Metallic Clad (JMC) flex (Seal-Tite® UA or Liquidtight® LA rated UL 94 V-0) may be run a distance greater than three feet only within bay end-guards and bases to connect light switches and bay test receptacles. The JMC shall not have excessive slack or be coiled within the bay end-guard or base.
AC/DC Power and Batteries – AC Power in the DC Operating (Regulated) Environment – AC Test Receptacles
All work on AC circuits shall be done in compliance with the technical requirements of the NEC and applicable local electrical codes. Note: AC circuits serving communications equipment and lighting are exempt from the administrative requirements of the NEC and local electrical codes for example, permitting and inspection.
While work is being done on AC circuits, fuses shall be removed or switches opened whenever it is practical to do so without causing a service interruption.
When work is being performed that requires removing the electrical potential from an operating circuit, the circuit shall be identified with a “Warning – Working on Circuit” tag at the AC source. The tag shall only be removed by the person performing the work. (a.k.a. “Lock-out, Tag-out”).
An Alternating Current Equipment Ground (ACEG) lead shall be provided with each AC circuit. When a conduit contains more than one AC circuit, one ACEG lead may be used if properly sized per the NEC.
AC/DC Power and Batteries – AC Power in the DC Operating (Regulated) Environment – AC Test Receptacles
The spacing of AC test receptacles shall be every third bay, not to exceed 10 feet in equipment frames. A single or stand-alone frame shall have a test receptacle provided or placed in the base. If a single or stand-alone bay to be installed has not been engineered with a test receptacle, the Installation Supplier shall contact the DESP for resolution.
AC test receptacles shall be mounted flush and equipped with a metal cover plate.
The Installation Supplier shall ensure that the grounding and polarity of AC test receptacles are correct, verified and recorded on the test record.
The entire length of the metallic raceway, conduit or trough shall provide a continuous conductive path for grounding.
The Installation Supplier shall install bushings, nipples or connectors to protect wiring. Exposed AC conductors shall not be in contact with edges of metal frameworks, boxes or raceways (e.g. running through a knockout).
AC/DC Power and Batteries – AC Power in the DC Operating (Regulated) Environment – AC Test Receptacles
Isolated ground AC receptacles (orange) shall not be installed.
Dedicated (non test receptacle) AC receptacles shall be installed in the same bay/frame as the equipment load the receptacle serves.
The Installation Supplier shall install a green ACEG lead for all AC lighting fixtures.
Wire and cable utilized to distribute AC power shall be exclusively copper conductors.
A wire nut shall be used to cover the exposed ends of all AC conductors.
Wire nuts shall meet the V-1 oxygen index rating or better.
The maximum number of duplex appliance outlets allowed on a branch circuit shall not exceed 20 for a 15 Ampere circuit breaker or 26 for a 20 Ampere circuit breaker.
Branch circuit conductors serving appliance outlets shall be, at a minimum, #12 AWG copper and no larger than #8 AWG copper. All conductors shall be insulated to 600 volts and meet the requirements of the National Electrical Code.
From a PDSC to the end of a branch circuit serving duplex appliance outlets, the length of the branch circuit shall not exceed:
• 145 feet for #12 AWG conductors
• 225 feet for #10 AWG conductors
• 360 feet for #8 AWG conductors
AC/DC Power and Batteries – AC Power in the DC Operating (Regulated) Environment – Conduit
Refer to Section I of ATT-TP-76300 for information regarding conduit.
AC/DC Power and Batteries – AC Power in the DC Operating (Regulated) Environment – Branch Circuits
When adding new branch circuits, fluorescent lighting or extending existing circuits, the Installation Supplier shall verify that no additional connection is made between the added neutral (white wire) and the required green wire ground (ACEG).
When extending an existing circuit, the Installation Supplier shall insure that the rating of the circuit protection device is not exceeded.
AC/DC Power and Batteries – AC Power in the DC Operating (Regulated) Environment – Lighting
Airey-Thompson lighting fixtures shall be installed per manufacturer’s instructions.
LumiCool lighting fixtures shall be installed per manufacturer’s instruction and ATT-TP-76202.