Deep-SeaLite®
User
Manual
6/19/02
2
deployment.
3) Check for condensation inside the glass envelope, especially after changing lamps. If any
condensation is evident, unscrew the connector/socket assembly from the body and remove
the lamp. Place the connector/socket assembly and lamp inside a warm oven (at least 100 C
or 212 deg F) for at least 30 minutes to bake out any moisture that may present. If possible,
purge with dry nitrogen while reassembling the light.
4) After each deployment, examine the power cable and rear connector for damage.
Lamp Changing Procedure: To change the lamp, simply unscrew the socket/connector assembly
from the light body and remove the old lamp by twisting counter-clockwise. When installing the
new lamp, be sure not to get any fingerprints on the surface of the lamp. Use a piece of tissue or
other clean paper to hold the lamp while installing it. Fingerprints can be cleaned from the
surface of the lamp with isoproply (rubbing) alcohol.
3.
Electrical Requirements
It is very important to use an appropriate power supply for each particular Deep-SeaLite®;
factors to consider are: voltage requirements (including voltage drop over long cable lengths),
current draw of the lamp, cold filament power surge, and lamp life at various voltages.
Voltage Requirements: The power supply must of course be able to supply sufficient voltage to
the light, however in many cases (especially with low voltage lights), the output voltage from the
power supply must be much higher than the lamp voltage. The reason for this is that a significant
amount of power is lost due to the electrical resistance of the power cable. The voltage drop
over a length of cable can be calculated by using the formula,
V = IR
, where V is the voltage
drop, I is the current draw of the light in amps, and R is the total electrical resistance of the
power cable in ohms. The current draw of a particular lamp can be calculated if the wattage and
voltage of the lamp are known. The current draw is equal to the lamp wattage divided by the
lamp voltage, or,
amps = watts/volts
.
For example, referring to the table of electrical resistances of various wire gauges listed below,
we can calculate the voltage required to operate a 24 volt-300 watt light at 24 volts over 250 feet
of 16 gauge cable. The current draw of a 24 volt-300 watt lamp operating at 24 volts is 300
watts/24 volts = 12.5 amps. The resistance of 16 gauge wire is approximately 4 ohms/1000 feet.
Since the total path of the circuit is from the power supply to the light and back to the power
supply, the total resistance of the cable is twice the length of the cable times the linear
resistance
, or for this example, R = (2 x 250 ft) x (4 ohms/1000 ft) = 2.0 ohms. Since V = IR,
the voltage drop, V is equal to 12.5 amps x 2.0 ohms = 25 volts. This means that 25 volts is lost
due to resistance and so the power supply will need to provide at least 49 volts to power this 24
volt-300 watt light over a 250 foot cable!
Wire Gauge
Ohms/1000 ft (approx)
20
10
18
6
16
4
