center at center of the base. Circle shall be constructed using an
emulsified asphalt-sand mixture or of a cut-back asphalt-sand mixture not
less than 125 mm 5 inches in thickness. Asphalt-sand mixture shall contain
not less than 6 percent bitumen. Sand shall be well-graded with not more
than 10 percent material which will pass through a No. 200 mesh sieve.
Asphalt-sand mixture shall be compacted thoroughly and sloped for drainage
from center to outer rim from one side to the other. Wind cone direction
indicator shall be guyed as indicated. The wind cone illumination lights
and obstruction lights shall be energized from [multiple] [series] [series
or multiple] circuits as shown by the contract drawings or as required
otherwise.
3.19
ISOLATION TRANSFORMERS
Transformer lead connections shall conform to FAA AC 150/5345-26.
Transformer secondary connectors shall plug directly into a mating
connector on the transformer secondary leads. During installation, mating
surfaces of connectors shall be covered until connected and clean when
plugged together. At joint where connectors come together, heat shrinkable
tubing shall be installed with waterproof sealant or with two half-lapped
layers of tape over the entire joint. Joint shall prevent entrapment of
air which might subsequently loosen the joint.
3.20
RUNWAY AND TAXIWAY LIGHTING SYSTEMS
3.20.1
Runway and Taxiway Edge Lights
Edge lights shall be elevated type lights except in paved areas where
semiflush lights are required. Threshold and runway end lights shall be
[elevated] [semiflush] type as indicated on the contract drawings.
Elevated lights shall be frangibly mounted and each light supplied power
through an isolation transformer. The taxiway lights shall be
omnidirectional and only require leveling. The runway lights require
leveling and alignment of the beams for the correct toe-in of the beams.
3.20.2
Runway and Taxiway Centerline Lights
These lights may be mounted on light bases or in drilled holes as indicated
on contract drawings. A transformer shall be provided for each group of
four 45-watt or three 65-watt centerline lights and installed in a handhole
as indicated on the contract drawings. Each light shall be provided with
lamp failure shorting device to allow the other lights to operate if one
lamp fails. Lights shall be connected to secondary circuit wires at
fixture leads using preinsulated watertight connector sleeves crimped with
a tool that requires a complete crimp before tool can be removed.
Connection shall be at staggered locations and wrapped with one layer of
half-lapped plastic electrical insulating tape. Light fixtures shall be
installed in holes drilled in the pavement as indicated.
3.20.3
Touchdown Zone Lighting Installation
A light base shall be provided for each light and transformer as indicated.
In making cable connections, sufficient slack cable shall be provided in
each base to permit connection to the upper part of the base or as
indicated.
3.21
APPROACH LIGHTING SYSTEMS
Approach lighting system shall be installed as indicated or as required
SECTION 16526A
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