11.7 Temporary Electric Power Service
For temporary electric power service during construction, consultants shall include the following requirements in the specifications. These requirements are usually found in:
Technical Specifications
Temporary Facilities and Control
Section 01500
Part 2 – Products
2.2 Equipment
H. Power Distribution System: Service entrance drop cable to the first disconnect may be aluminum, subject to conditions specified in Part 3 of this specification. Circuit wiring conductors, inward from the first disconnect, shall be copper.
I. Power Distribution System Circuits: Circuits for temporary power distribution and lighting, not exceeding 125 volts AC, 20 ampere rating, may be permitted to use nonmetallic sheathed cable, provided that:
a. The installation meets requirements of the NEC, and
b. The cables are installed overhead and left exposed for surveillance.
Add the following new language to:
“Part 3 – Execution”, under Section 3.2 Temporary Utility Installation
If, as allowed under Part 2 – Products above, aluminum conductors are used for service drops, they shall be inspected monthly for the duration of their use. A written report on the cable condition shall be submitted to the MDOT MAA’s authorized inspection firm.
11.7.1 Back-up Generator Requirements for Electrical Work (BWI Marshall Only)
This standard includes requirements for temporary emergency electrical generators for use during construction activities at BWI Marshall Airport. This standard addresses temporary generator requirements resulting from outages on the BWI Marshall distribution system from the utility service entrance locations down to and including the BWI Marshall customer utilization voltage equipment. During the planning and design phase, a study by the Consultant shall be conducted to determine the requirements of backup generator(s). Based on cost and the Consultant’s recommendation, the MDOT MAA Project Manager shall determine if a backup generator is necessary.
A. The BWI Marshall medium voltage distribution system consists of the following major components:
1. Two utility service entrance substations designated North Substation and South Substation. These substations are located approximately on opposite sides of the Airport and are each supplied from a separate utility company feeder.
2. Multiple switchgear locations designated Switchgear #1, Switchgear #2 and Switchgear #3 (future, anticipated on-line May, 2004). Each switchgear is supplied by two feeders, one feeder from the North Substation and the other from the South Substation.
3. Multiple customer utilization voltage equipment (13,800 volt primary voltage, 480 volt or 4,160 volt secondary voltage) consisting of a double-ended unit substation, single ended unit substation or separate entrance transformer. All customer utilization voltage equipment is supplied from Switchgear #1, Switchgear #2 or Switchgear #3. Most of the customer utilization voltage equipment consists of double ended unit substations supplied by both a north and south switchgear feeder. The remaining customer utilization voltage equipment locations are supplied by a single switchgear feeder.
B. The consultant shall perform the following activities during the design phase of the project:
1. Contact the Maryland Aviation Administration (MDOT MAA) to obtain a current BWI Marshall medium voltage distribution system diagram that shows all electrical equipment from the North and South Substations down to and including all customer utilization voltage equipment at the secondary voltage level.
2. Develop and submit for approval a project specific electrical equipment outage and equipment switching schedule including, but not limited to, the location, number, duration and time of day for all anticipated electrical outages and associated equipment switching activities for all BWI Marshall distribution system electrical equipment from the North and South Substations down to and including all customer utilization voltage equipment at the secondary voltage level. An outage is defined as the electrical de-energization of any electrical equipment within the scope of this standard for any length of time. All outages shall be included regardless of duration. Whenever equipment is supplied by both a north and south feeder, the de-energization of one of the two feeders shall be considered an equipment outage. All switching activities shall be included regardless of outage impact.
3. Develop and submit for review a project specific temporary emergency electrical generator plan including proposed temporary emergency generator set size(s) as required for the electrical outages and/or switching operations. MDOT MAA shall be contacted for specific generator requirements.
4. Include all temporary generator requirements in the bid documents for the project.
5. All temporary emergency electrical generator requirements shall be coordinated with and approved by MDOT MAA Operations and MDOT MAA Office of Facilities Maintenance on a case-by-case basis.
C. Electrical outages shall be scheduled in accordance with, but not limited to, the following requirements:
1. All work that may potentially cause any electrical outage shall be performed during non-peak hours (usually from 12:00 midnight through 5:00 AM) unless otherwise approved by MDOT MAA. The consultant shall obtain the Engineer’s approval for electrical outage periods.
2. Equipment outages shall be allowed on only one major electrical equipment item at any one time unless otherwise approved by MDOT MAA.
3. All outage durations shall be kept to a minimum.
4. Any work requiring a sustained electrical outage shall be performed continuously around the clock until work is completed unless otherwise approved by MDOT MAA.
5. Whenever equipment is supplied by both a north and south feeder, at least one feeder shall remain connected and active unless otherwise approved by MDOT MAA. The de-energization of one of the two supply feeders (North or South) shall be considered an outage for the purpose of this standard.
Temporary emergency electrical generators shall be diesel powered, low noise, self-contained on a dedicated containerized mobile trailer with integral fuel tank and fuel spillage containment system.