Under water pool lights

Jul 18, 2012
2
I have a 12volt bulb in my two under water pool lights. I have the output of my transformer set for 14 volts. I measure 11 volts across the connections when it is connected to the lights. Is this ok or should it read higher? The bulbs are not lighting.
 
I suppose you don't know if the output has always been 11volts do you?

Longer electrical runs will see voltage drop. But since they worked before, that can probably be eliminated as an issue.

Are you sure your not taking a reading before the gfci, and it tripped?
 
My 12 volt transformer reads 13.4 V across the leads when bench tested.

they are pool light sources, not refrence voltage generators, I don't think the tolerances are that tight.

With mine at 13.4 volts it lights up my 12 V bulb just fine. I have never measured what it reads with the bulb attached.

How/when did it stop working? All of a sudden, after a period of non-use, never worked?

-dave
 
This is a 45 year old pool which I just inherited. There is no ground fault and I don't know what the load voltage was because the transformer burnt out. I replaced the transformer and had two new bulbs put in. Tomorrow I will measure the total load resistance and see if I can figure the voltage drop. I guess I should pull the lights out and see if I can measure the voltage across the bulb. Any other ideas?
Thanks so much for your interest in this. I hope I posted this correctly since this is my first post.
Bob
 
11v should be fine
it will run at 9v but they will be dim

you will have a loss in voltage over your lenght of run and the gauge of wire will also effect how much of a loss

take the bulb and put your meter on it and check for continutiy, it will beep if the bulb is good, it will not if it is bad

or hook it up to a car battery and see if it lights

if you have voltage at the socket, i would suspect the bulb itself
 
What kind of pool do you have? At 45 years, whatever it is, it is showing it's age.

I know with my light, if you leave the lamp in over winter, it can be damaged (old owner did that - $50 for a new bulb)

I pulled the power supply from the pool, and tested it on the bench (and got 13.4 V) then I ohmed out the lamp and got an open. That's when I decided that a $50 new lamp was most likely the answer (I turned out it was the answer)

-dave
 
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