2 hanging candelabra style lum-inaires, each with three 40w bulbs...

owner says have always been dim since house was built... today a bulb burns out in the upper lum. and the other 2 bulbs in that lum. get brighter, at the same time the other 3 bulbs in the lower lum. get dimmer. so they put a new bulb in the upper lum. and the 2 lum's balance out as before... both lum.'s revert to being as equally dim as they have always been

so, they tested it...
they screw the 3rd bulb into the upper lum., and the lum.'s are equally dim, all 6 bulbs dim.
then they unscrew that 3rd upper lum. bulb and the other 2 upper lum. bulbs get brighter, and the 3 lower lum. bulbs get dimmer

is this obvious to the most casual observer? i bet its really easy and i'm going to be embarrassed [again] ;-)

Cindy, it sounds like a strange series/parallel connection of the sockets from the factory. Are the 2 luminaires hung separately or are they a factory combination unit? Has the voltage been checked at different points of that circuit, starting at the switch?


steve

Cindy-, I agree with stamcon, luminaire is wired in series......sockets that is. Must be a common place on the luminaire where you can change the connections. Hope this helps.

they are 2 identical lights.... one at top of stairs, one at bottom of stairs. will check voltages

Cindy, I agree with the series wiring but not necesarily in the fixtures. Think of the fixtures being reisistors in a series circuit (the house wiring, in this case the three way wiring) and by removing a piece of the resistor (one lamp) you are changing the voltage drop across this resistor.(luminare)


For fun remove all the lamps from one fixture and see what happens.

Roger

I'll just bet that the 3-way travellers go from switch to light to light to switch, and that there are only three conductors between the two lights.

In this threeway scenario, one needs four wires between the lights for each light fixture to be in parallel with the switched leg and the neutral.

I'll bet when the original installer found his(er) mistake, the two fixtures were put in series with each other and connected between the switched leg and the neutral. Some light is better than no light (and maybe no one will notice .

Cindy,- Sorry,my reply is wrong, I thougth it was only one luminaire. Guess I was not as awake as I thougth at 5:30 am.

It does sounds as though the fixtures have been wired in series somehow, in which case if you remove all the bulbs from one, the other should stay dark as well.

Assuming that both lights are switched together on 3-ways top and bottom of the stairs, do they react the same way when the switches are turned on the "other" way? (e.g. if both up=on, do the lights still act like this when both switches are down?).

thanks, good ideas..... will check voltages and travelers... will see if in series too removing bulbs, but the position of the 3-way didn't make a difference... they used to have normal 3-way snap switches but now have X-10 types with master and slave, but it never worked right with either set of switches... thanks again

Would love to see how this was wired, as the current setup has resulted in a Voltage Divider Network!

Cindy;
When / if this does get fixed, please post the connection scenario here!

If this was a simple Series setup, one lamp would kill all.

If a Series Parallel setup, one Luminaire would not effect the other.

This could only be a Voltage Divider Network!

Crazy, huh!

Scott35

owner wants to fix it himself so won't see it, but he says it only has two 14/2 nm cables at each light... a 14/3 at the upper switch, and a 14/2 and a 14/3 nm cable at the lower box, one of them is the line in... we assume that the two 14/2's are going between the lights

It sounds as though this might remain an unsolved mystery then, but we can still conjecture.

If the 14/2 at the lower switch box is hot and neutral in, then the 14/3 going out must carry the neutral and two travelers. There would have to be another junction box somewhere if this is the case.

Could it be that the 14/2 at the lower switch is not actually hot and neutral but a
switch loop? (I don't suppose you can remember the connections, can you?)

I can see a scenario where power enters one light fixture box on a 14/2, there is a 14/2 run between the lights, and the other 14/2 at the second light is the switch loop down to the lower switch. The 14/3 then runs directrly between the two switches.

With this physical arrangement of cables the lights could only end up being in series. Replacing the 14/2 between the lights with a 14/3 would allow proper operation.

But as you said, you'll probably never know.

it would be fun to figure this out, so i may volunteer some time on this one just for fun