I would appreciate some help with a 12 volt question.

I set up a 7 light long string of 12 volt, 40 watt bulbs on a strand
of 12 guage, outdoor lighting, copper wire. The bulbs and bases were
standard Edison screw base types. The lights were connected to a 300
watt DC converter made for outdoor yard lights. In theory, I would
like to take the same string (with lower wattage bulbs) on sailing
trips.

In 4 days, 6 of the seven lights have burned out. One light continues
to burn at normal brightness.

Any ideas or comments on these failures apprecitated.

Thanks
Tom

Overvoltage is my guess....... measure the voltage on any one of the bulbs.

-W

"Tom Best" wrote in message
om...
I would appreciate some help with a 12 volt question.

I set up a 7 light long string of 12 volt, 40 watt bulbs on a strand
of 12 guage, outdoor lighting, copper wire. The bulbs and bases were
standard Edison screw base types. The lights were connected to a 300
watt DC converter made for outdoor yard lights. In theory, I would
like to take the same string (with lower wattage bulbs) on sailing
trips.

In 4 days, 6 of the seven lights have burned out. One light continues
to burn at normal brightness.

Any ideas or comments on these failures apprecitated.

Thanks
Tom

Any ideas or comments on these failures appreciated.
In the time I've spent as an Aviation Electrician, I've seen incandescent
bulbs fail for many reasons including: vibration, exposure to temperature
extremes, poor quality construction, over voltage, and "hot spots" caused by
fingerprints on the globe.

If you can eliminate most (or all) of these causes, I'd expect your bulb
life to increase.

My 2¢


(¯`·._.· £ãrrÿ ·._.·´¯)




"Tom Best" wrote in message
om...
I would appreciate some help with a 12 volt question.

I set up a 7 light long string of 12 volt, 40 watt bulbs on a strand
of 12 guage, outdoor lighting, copper wire. The bulbs and bases were
standard Edison screw base types. The lights were connected to a 300
watt DC converter made for outdoor yard lights. In theory, I would
like to take the same string (with lower wattage bulbs) on sailing
trips.

In 4 days, 6 of the seven lights have burned out. One light continues
to burn at normal brightness.

Any ideas or comments on these failures apprecitated.

Thanks
Tom

Tom,

Regarding that converter for 'outdoor yard lights', do you have the
instructions for that converter/transformer? I have a few Malibu sets
but the highest output unit I'm using is an 88 watt unit. I can't
remember the exact distance, but believe the first (landscape) light
off the unit should be a minimum of 10 feet from that converter. This
is due to the rapid pace that DC voltage drops over distance. If you
measure the voltage at the converter and at the end of the run, you'll
see what I mean. Easier to see with the typically crappy undersized
wire that manufacturers like to provide. Also, using 12 ga wire, and
assuming a short run, you are probably getting minimal to no voltage
loss and could very well have an overvoltage condition. First check
and see what the voltage is at the first light to see if it is too high
for what you are trying to do. Also, I don't believe the DC coming out
of those units would be too clean, but don't know if it would cause a
problem for those bulbs.

-JimL


Tom Best wrote:
I would appreciate some help with a 12 volt question.

I set up a 7 light long string of 12 volt, 40 watt bulbs on a strand
of 12 guage, outdoor lighting, copper wire. The bulbs and bases were
standard Edison screw base types. The lights were connected to a 300
watt DC converter made for outdoor yard lights. In theory, I would
like to take the same string (with lower wattage bulbs) on sailing
trips.

In 4 days, 6 of the seven lights have burned out. One light continues
to burn at normal brightness.

Any ideas or comments on these failures apprecitated.

Thanks
Tom

TOM make sure that your circuit is a parrallel one, not in series.Also you
cannot reduce the watt of the bulb because you will reduce the resistance of
your circuit and let pass to much current on the same bulb (burning action)


"Tom Best" a écrit dans le message de
om...
I would appreciate some help with a 12 volt question.

I set up a 7 light long string of 12 volt, 40 watt bulbs on a strand
of 12 guage, outdoor lighting, copper wire. The bulbs and bases were
standard Edison screw base types. The lights were connected to a 300
watt DC converter made for outdoor yard lights. In theory, I would
like to take the same string (with lower wattage bulbs) on sailing
trips.

In 4 days, 6 of the seven lights have burned out. One light continues
to burn at normal brightness.

Any ideas or comments on these failures apprecitated.

Thanks
Tom

"jean" wrote in message
...
TOM make sure that your circuit is a parrallel one, not in series.Also you
cannot reduce the watt of the bulb because you will reduce the resistance
of
your circuit and let pass to much current on the same bulb (burning
action)

This is incorrect. If you reduce the wattage of the globe, the resistance
will INCREASE as it will draw LESS current at the same voltage to get the
lower power.
( Power = Voltage*Voltage/Resistance). As the bulbs progressively failed, it
is obvious that they must be in parallel as they would all go out if any one
failed in a series circuit.

regards,
Mark

Check the voltage. My Malibu is 12V AC from what I remember.

"Tom Best" wrote in message
om...
I would appreciate some help with a 12 volt question.

I set up a 7 light long string of 12 volt, 40 watt bulbs on a strand
of 12 guage, outdoor lighting, copper wire. The bulbs and bases were
standard Edison screw base types. The lights were connected to a 300
watt DC converter made for outdoor yard lights. In theory, I would
like to take the same string (with lower wattage bulbs) on sailing
trips.

In 4 days, 6 of the seven lights have burned out. One light continues
to burn at normal brightness.

Any ideas or comments on these failures apprecitated.

Thanks
Tom

"Tom Best" wrote in message
om...
I would appreciate some help with a 12 volt question.

I would think it would be from excessive vibration if they were
originally for fixed service in the yard.

Leanne

jean wrote:

TOM make sure that your circuit is a parrallel one, not in series.Also you
cannot reduce the watt of the bulb because you will reduce the resistance of
your circuit and let pass to much current on the same bulb (burning action)


jean;
1) The original poster stated that he had seven (7) bulbs "in
parallel", so that's not an issue.
2) Do not understand your "reduce the watt of the bulb"
statement. It appears wrong. If you reduce the wattage LESS
current will flow (Volts x current = watts). And the resistance
will INCREASE. Basic Ohms Law!
Example: 12 volts x 1 amp = 12 watts. Resistance of lamp is
Volts/Amp = 12/1 = 12 ohms.
Example: 12 volts x 2 amps = 24 watts. Resistance of lamp is
.......12/2 = 6 ohms.
Thus: Twice the resistance results in half the wattage.

jean,

I'm confused on what you're saying. 40 watts is the current limit
for the bulb, period! Unless of course the voltage is too high
thereby forcing more current through. From what I see of these
outdoor converters, the voltage output is constant. Manufacturers
just don't want you to overdrive them with more wattage of bulbs
than the trancformer can put out.

-JimL

jean wrote:
TOM make sure that your circuit is a parrallel one, not in series.Also you
cannot reduce the watt of the bulb because you will reduce the resistance of
your circuit and let pass to much current on the same bulb (burning action)


"Tom Best" a écrit dans le message de
om...

I would appreciate some help with a 12 volt question.

I set up a 7 light long string of 12 volt, 40 watt bulbs on a strand
of 12 guage, outdoor lighting, copper wire. The bulbs and bases were
standard Edison screw base types. The lights were connected to a 300
watt DC converter made for outdoor yard lights. In theory, I would
like to take the same string (with lower wattage bulbs) on sailing
trips.

In 4 days, 6 of the seven lights have burned out. One light continues
to burn at normal brightness.

Any ideas or comments on these failures apprecitated.

Thanks
Tom