| 1.
ELECTRICAL |
| |
a) |
Contact
material shall be silver impregnated/silver plate copper. They shall use
a ball and socket design for ease of alignment and to allow for residual
vibration and forces created by winds. |
| |
b) |
Contact
pressure shall be supplied by springs remote from the current conductors,
and in no way should be part of the current carrying path. |
| |
c) |
Termination
of wire should be to crimp type connectors. |
| |
d) |
Electrical
insulation of contacts should be provided by porcelain standoffs. |
| |
e) |
Lowering
device should be make and break rated so that the fixture need not be
remotely isolated before lowering. These make and break ratings shall
be as follows: 250 VAC - 30 amps 600 VAC - 15 amps 250 VDC - 10 amps |
| |
f) |
Lowering
device shall have (4) contacts as standard. |
| |
| 2.
MECHANICAL OPERATION |
| |
a) |
System
shall support weight of all Obstruction Lights available in the classification
of the specified Obstruction lights, so that substitutions can be made
without major disruption of the system. |
| |
b) |
System
shall be operated by portable winch with separate operating line and winch
line or fixed winch with a continuous operating line and winch line supplied
by the lowering device manufacturer. |
| |
c) |
Device
shall be manufactured with cast aluminum for the housing. |
| |
d) |
Operation
must be a slow pull/quick release method. This movement shall be facilitated
be a trip lever provided by the lowering device manufacturer. |
| |
e) |
Device
shall be of a maintenance-free design. |
| |
f) |
Latching
shall be a single point centered design to facilitate even wear over the
life of the hanger. |
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| 3.
SYSTEM |
| |
a) |
Upper
or fixed housing of lowering devices shall contain: aa. attached pulley
bb. single point latching mechanism cc. guide dd. upper (socket) electrical
contacts ee. mast arm for attachment of device to structure ff. termination
location for for fixture guide line |
| |
b) |
Lower or moveable housing of lowering device shall contain: aa. operating
line termination bb. positioning stem and latch assembly cc. lower (ball)
electrical contacts dd. fixture adapter |
| |
c) |
Fixtures
shall be lowered on a guide line to allow operation of system in adverse
weather and structural clearance. The angles of the guide line to the
structure shall be to lowering device manufacturer's instructions. |
| |
d) |
Operating
line shall be special quality high strength/high flexibility stainless
steel and be supplied by the lowering device manufacturer. |
| |
e) |
Each
turn in the structure must provide a transitional pulley assembly for
the operating line consisting of pulleys, and flare ends (if enclosed
in conduit) to prevent cable rub and/or snags on the conduit runs. |
| |
f) |
Each operating line run shall be encased in conduit or supported by pulleys
placed at intervals suggested by the lowering device manufacturer. |
