New Halogen is acting strangely.

L124C · #1 (**permalink**) 02-09-2011

Just replaced a fluorescent fixture in the Head with a halogen red/white dome light. The light is mounted on a bulkhead and shares wiring with another pre existing halogen on the opposite side of the bulkhead. The lights share the same power supply, but are switched independently (at each light). Both lights work fine, but occasionally, if I have them both on, they will shut off. If I flick the switch on the older light, the new one sometimes comes on, sometimes with diminished light, sometimes with full light! If I shut them both off for a while, they work fine (for a while). What gives?

sailingdog · #2 (**permalink**) 02-09-2011

Sounds like you have a bad switch in the new light fixture.

L124C · #3 (**permalink**) 02-09-2011

Quote:

Originally Posted by sailingdog

Sounds like you have a bad switch in the new light fixture.

The older light isn't switched with the new fixture. It only shares power (pre switch). Why would the older light go out as well? Almost seems like thy get overloaded at the same time. I'm not blowing fuses, and both lights work perfectly, until they don't. Really strange! I used about 2 feet of 18 guage wire from the supply line to the lights. Could this have anything to do with it?

sailingdog · #4 (**permalink**) 02-09-2011

If the switch was good, the halogen light would never go on, unless you turned it on. By definition, if the switch is off, the light CAN NOT TURN ON. You're not touching the light switch on the halogen light when it goes on by itself. Therefore, the switch is bad. There is obviously something else going on to explain the other issues, but you've got to deal with one problem at a time.

rmeador · #5 (**permalink**) 02-09-2011

SD, I could be wrong, but I interpreted L124C's comment about the new light coming on after he flicks the switch on the old light to mean AFTER they have spontaneously turned themselves off. This makes a sort of sense if there is some kind of overload, since it would turn OFF the old light and thus leave more power for the new light (which turns on). It is still really fishy though. L124C, if you have a voltmeter (and I hope you do), try to get voltage readings at each of the bulbs when this weird phenomenon is happening. If the voltage at the bulb isn't close to 12V, work your way "up stream" towards the battery, checking the voltage wherever you can as you go (the light's switch, the place where the wires to the two lights come together, the fuse for the whole circuit). Post those results and we can probably help you more.

Oh, and another thing... you say it's a red/white light. I've never seen a halogen red/white light, only LED ones or LED combos. Is this one halogen for the white and LED for the red? If so, having it installed backwards could explain what you're seeing (LEDs have a polarity and must be hooked up the right way). Also, do you observe the behavior described in your original post in both red and white mode, or just one or the other?

mitiempo · #6 (**permalink**) 02-09-2011

I have halogen red/white so they are available.

I agree with checking the voltage. 18awg is a bit light for anything but leds I think if the run is very long especially. If the supply line is a heavier wire and you have just added 2 feet of 18awg that shouldn't be a problem.

The lights I have installed on my boat and others, ABI, Victory, and similar have cheap switches so that could be the problem. I have returned a couple for bad switches.

sailingdog · #7 (**permalink**) 02-09-2011

My bad.., I just went and re-read the OP a bit more closely. I would agree that there's something fishy going on. I would ask the OP to clarify what he means when he says that the two lamps share the same power supply?

Does he have a terminal block that goes back to the circuit breaker on the DC panel there? If so, what is size of the wiring going back and how long is the run?

Also, what wattage are the halogen bulbs he is using, 10 watt or 25 watt?

If they're both on and shutting off, it sure sounds like a circuit breaker is tripping. When you flick the switch on the old one, is that after they were both on and then the went off spontaneously? If so, that means the new fixture's switch is still in the "ON" position, correct?

Have you checked the voltage at the "power supply", both with the lights off and with the lights on? IF so, what is it? Have you checked the total resistance of the wiring up to the "power supply" point from the panel?

Quote:

Originally Posted by rmeador

SD, I could be wrong, but I interpreted L124C's comment about the new light coming on after he flicks the switch on the old light to mean AFTER they have spontaneously turned themselves off. This makes a sort of sense if there is some kind of overload, since it would turn OFF the old light and thus leave more power for the new light (which turns on). It is still really fishy though. L124C, if you have a voltmeter (and I hope you do), try to get voltage readings at each of the bulbs when this weird phenomenon is happening. If the voltage at the bulb isn't close to 12V, work your way "up stream" towards the battery, checking the voltage wherever you can as you go (the light's switch, the place where the wires to the two lights come together, the fuse for the whole circuit). Post those results and we can probably help you more.

Oh, and another thing... you say it's a red/white light. I've never seen a halogen red/white light, only LED ones or LED combos. Is this one halogen for the white and LED for the red? If so, having it installed backwards could explain what you're seeing (LEDs have a polarity and must be hooked up the right way). Also, do you observe the behavior described in your original post in both red and white mode, or just one or the other?

L124C · #8 (**permalink**) 02-09-2011

Quote:

Originally Posted by sailingdog

If the switch was good, the halogen light would never go on, unless you turned it on. By definition, if the switch is off, the light CAN NOT TURN ON. You're not touching the light switch on the halogen light when it goes on by itself. Therefore, the switch is bad. There is obviously something else going on to explain the other issues, but you've got to deal with one problem at a time.

DOWN DAWG...DOWN!

L124C · #9 (**permalink**) 02-09-2011

Quote:

Originally Posted by mitiempo

I have halogen red/white so they are available.

I agree with checking the voltage. 18awg is a bit light for anything but leds I think if the run is very long especially. If the supply line is a heavier wire and you have just added 2 feet of 18awg that shouldn't be a problem.

The lights I have installed on my boat and others, ABI, Victory, and similar have cheap switches so that could be the problem. I have returned a couple for bad switches.

Yep...they are halogens. I WISH I could get this much light from LED's! I also have some red/white fluorescent lights.
I agree the wirings a little light, but access was tight (Yes...THAT tight!!). I doubt the voltage problem is upstream. I'm thinking the wiring is too light as both halogens are reacting at the same time, and my turning the old one off must allow enough current to operate the old one by itself (hence, the re light, never having touched the new switch. If it is a gauge issue, I would have thought I would have seen diminished performance when I turned them both on, not ten minutes later, but I obviously don't understand exactly how Halogens work. Think I'll bypass the 18 GA with heavier wire (outside the head liner) and see if I can duplicate the issue.

sailingdog · #10 (**permalink**) 02-09-2011

I'd point out that as the wire heats up from too much current, its resistance will increase. As the resistance increases, the voltage at the lamps will drop. The delay may be caused by the wire cooling off and the heat-induced resistance disappearing as it cools.

Quote:

Originally Posted by L124C

Yep...they are halogens. I WISH I could get this much light from LED's! I also have some red/white fluorescent lights.
I agree the wirings a little light, but access was tight (Yes...THAT tight!!). I doubt the voltage problem is upstream. I'm thinking the wiring is too light as both halogens are reacting at the same time, and my turning the old one off must allow enough current to operate the old one by itself (hence, the re light, never having touched the new switch. If it is a gauge issue, I would have thought I would have seen diminished performance when I turned them both on, not ten minutes later, but I obviously don't understand exactly how Halogens work. Think I'll bypass the 18 GA with heavier wire (outside the head liner) and see if I can duplicate the issue.