Strange Problem

[CodyCookie]

Good Morning, I relamped a Navigation light, two standard lamp bases with led bulbs, 8.5w 120v.
When I install one lamp it goes on, when on install the second lamp it goes on and the first one goes off. Anyone have any idea what is happening ?

 

[Rock86]

(If this doesn't get locked) Do you have a picture of the wiring or a schematic of how you wired it?

 

[petersonra]

did it ever work?

 

[texie]

Many of these 2 light setups use an auto transfer system. One light normally on. If it fails the other turns on. Often also has some form of alarm to let the operator know the lamp is out. Also I would be sure the fixture is rated for the lamp you are using as this is usually very specific.

 

[CodyCookie]

Hello all, thank you for the comments, I did not wire this, it is an old set up, looking for some diagrams, could be part of the plc system, odd thing is there only seems to be one circuit in the fixture, very hard to work on, almost no access without a bucket snooper truck.

 

[CodyCookie]

did it ever work?

Not sure honestly.

 

[don_resqcapt19]

Typically there is no external control. There would be some type of current switch on the wiring to one of the sockets. As long as there is current flowing to that socket the contacts in the current switch that supply power to the other socket remain open. When the first lamp burns out, the current switch provides power to the other socket so that the navigation light remains on. In some cases there is an alarm contact to let someone know that a lamp has failed, but typically, you just have to look at the fixture to see which of the two lamps are lit to know if a lamp has burned out.

 

[hillbilly1]

If it’s a current switch, it’s probably not going to work well with LED lamps, the current draw will probably be too low. Same problem as when vehicle taillights are changed to LED, if the turn signal flasher is current driven, not enough current to make them flash.

 

[GoldDigger]

If it’s a current switch, it’s probably not going to work well with LED lamps, the current draw will probably be too low. Same problem as when vehicle taillights are changed to LED, if the turn signal flasher is current driven, not enough current to make them flash.

But it apparently does work with his paricular fixture and LEDs. Otherwise the first lamp installed would have kept working.

 

[CodyCookie]

Typically there is no external control. There would be some type of current switch on the wiring to one of the sockets. As long as there is current flowing to that socket the contacts in the current switch that supply power to the other socket remain open. When the first lamp burns out, the current switch provides power to the other socket so that the navigation light remains on. In some cases there is an alarm contact to let someone know that a lamp has failed, but typically, you just have to look at the fixture to see which of the two lamps are lit to know if a lamp has burned out.

Thank You
I will see If I can get in there and find a current switch. Simple enough.

 

[hillbilly1]

But it apparently does work with his paricular fixture and LEDs. Otherwise the first lamp installed would have kept working.

I would say it isn’t working, (with the LED) because the first lamp went out because it wasn’t drawing enough current to keep it on the primary lamp, and failed to the secondary, even though the primary was still good.

 

[GoldDigger]

I would say it isn’t working, (with the LED) because the first lamp went out because it wasn’t drawing enough current to keep it on the primary lamp, and failed to the secondary, even though the primary was still good.

It is working exactly as it should if the first socket to get a lamp installed was the secondary socket.

 

[hillbilly1]

It is working exactly as it should if the first socket to get a lamp installed was the secondary socket.

If a regular lamp is used, what I’m saying is, it is not working as intended with the LED lamp. The safety backup is no longer there.

 

[CodyCookie]

It is working exactly as it should if the first socket to get a lamp installed was the secondary socket.

Yes Sir
Thank You

 

[wwhitney]

My understanding: Socket 1 is powered always. Socket 2 is powered only when insufficient current is drawn on Socket 1. [If the current switch cut Socket 1 out of the circuit, then it could never notice when Socket 1 would start drawing sufficient current.]

So the behavior described in the OP shows that the LED lamps draw sufficient current. The first lamp happened to be put in Socket 2. Then when the second lamp was put in Socket 1, there was sufficient current drawn, and Socket 2 got shut off.

If the LED lamps weren't drawing sufficient current to trigger the current switch, then both lamps would be lit. At least per my inference of how the current switch must be wired for the system to work as described..

Cheers, Wayne

 

[RumRunner]

My understanding: Socket 1 is powered always. Socket 2 is powered only when insufficient current is drawn on Socket 1. [If the current switch cut Socket 1 out of the circuit, then it could never notice when Socket 1 would start drawing sufficient current.]

So the behavior described in the OP shows that the LED lamps draw sufficient current. The first lamp happened to be put in Socket 2. Then when the second lamp was put in Socket 1, there was sufficient current drawn, and Socket 2 got shut off.

If the LED lamps weren't drawing sufficient current to trigger the current switch, then both lamps would be lit. At least per my inference of how the current switch must be wired for the system to work as described..

Cheers, Wayne

Bingo!
This concept is similar to automobile directional signal.
Replacing the incandescent bulb with an LED creates this problem--
which confuses auto mechanics or automotive electricians.

The old blinking signal lights work on the same principle as you described. This is an idea applied more than several decades ago.
A filament is in series with a bi-metal element that opens when heated (when current is flowing) and then closes when cooled.

This concept is then applied to navigational warning light that are required in tall structures near airports.

This is covered by some posters.
This two-bulb switching feature increases its reliability. . . that tells maintenance that one bulb is burned out.
The suggested solution is:

Check the wattage of the old incandescent bulbs.

It seems like the new LED lamps are too small to draw enough current to activate the switching feature.
The usual solution for signal lights for automobile is-- to add a resistor load-- to increase the current load for the transfer to function. Usually connected in parallel with the load.

This is kind of a paradox since the owner probably wants to reduce power or minimize maintenance-- but by adding an extraneous load (the resistor) defeats the purpose.

BTW:
Navigational lights usually come more than 8.5 watts. This wattage is like a night light in a bedroom. Even a warning light used in fire alarms are rated 30 watts –smallest.
They were strobe.
The last one I installed years ago was rated more than a 100 watts IIRC. It is visible for quite some distance.

 

[wwhitney]

It seems like the new LED lamps are too small to draw enough current to activate the switching feature.

Why do you say that? If one socket is always on, and the other one switched, then plugging in the second lamp and having the first turn off shows it is working properly. As I said, if the current were too small, both lamps would be lit.

Cheers, Wayne

 

[Ken_S]

It's working fine, you wouldn't know which base is the primary until you installed the lamps.

Is the fixture from B&B Roadway?

FYI, the older transfer relays will not work with LEDs, but that doesn't seem to be an issue for you