Pool Light Transformer Voltage

[adam_d]

Light in my pool is currently not working. Worked last season though. I have it ran through a 120v to 12/13/14V transformer.

At this point, not sure of the light manufacturer as I've yet to pull it from the pool.

When testing voltage today, I found that I do have 120v coming into the transformer but my usual connection of 12v only gives off 8v, 13v gives off 9v and 14v gives off 10v. Think my transformer is dying, however, I've read that these usually just go out totally.

For kicks, I went ahead and connected it to the 14v (to get 10v) but light still doesn't come on, not even a little. Hence my questions:

1.) Does a pool light need the necessary voltage to work, even at a dimmed capacity?

2.) Is there anymore testing I could do to verify it's the transformer and not the bulb/light fixture?

Thanks in advance!

 

[JohnT]

A shorted winding in a transformer will give you low output.

 

[jza1736]

Led lights usually will have a tolerance for voltage. Say 11-14 volts but if your under their specs they won't light. If your close they may blink. Also if your testing at the xfmr the voltage at the light will most likely be lower

 

[adam_d]

Thanks for the input! I want to say it's a halogen bulb if that makes a difference. I was testing at the transformer, and yes I believe the voltage at the light was a bit lower. Will double check today. Think I'll eventually get around to switching out the transformer to hopefully fix the issue.

 

[adam_d]

UPDATE:

Received a out-of-box but never used Intermatic PX300. New problem is voltage coming from the transformer. I have 120V coming from my breaker, when reading output, I get 120V on the 12V, 130V on the 13V and 140V on the 14V. Maybe my multimeter is bad? It's a cheap one. I'm going to use a friends to see if I get different results tomorrow. Otherwise my transformer isn't doing it's job.

EDIT**

I'm having some inconsistencies between my old and new transformer. The old one, I wired my 120V from the breaker to a black wire, then it had 3 wires to choose from for output (12,13,14V to go to the pool light).
My new one has the following diagram. It says to connect 120V from breaker to either the 12,13, or 14 and then hook the black wire up to the pool light. However when I do this, the black wire still gives off 120V for 12, 130V for 13 and 140V for 14.

Going to check to see if wiring it the other way would help anything.

 

[jza1736]

Are you metering the 2 black wires on the output side? They should be 12v. The black wire on the input side will always have 120v if it's connected to the hot leg. Make sure you safe off the blue and yellow if you are not using them

 

[adam_d]

yes, checking the 2 output wires. 1 shows 120V and the other shows 0. The one that shows voltage jumps depending on which input voltage I have it set on.

To add, I have the white neutral from the transformer hooked up to the white from the breaker. But this diagram shows it linked on the output side?

I'm assuming the neutral from the pool light goes on one of the black output wires (even though I haven't gotten that far)

 

[jza1736]

Are you checking them to ground or to each other? You should only have 1 reading

 

[adam_d]

To ground. When measured together, I get 120V. In your earlier post, you said 'black wire on the input side will always have 120V" - which wire are you talking about? The black wire on the input is connected to the 120V breaker, there isn't any other black wire - unless you meant the one you hook up to the breaker.

So yes, I have 120V going into the transformer, and still 120V coming out. Hopefully a bad multimeter reading is the cause otherwise I'm returning this (even though it appears brand new?)

 

[jza1736]

From your diagram there are 2 black wires on the output side. Those are your secondary side. The voltage will change depending on what color you slice on the input side. Black will be 12 volts, yellow 13, and blue 14

 

[adam_d]

That's how it should work yes, however, from the secondary side, I'm still receiving 120V, yellow 130V, and blue 140V.

 

[jza1736]

I think you have the primary and secondary backwards. The side with the 3 wires (black, blue, and yellow) is the primary side

 

[adam_d]

Transformer voltage is reading correctly now. Had 1 wire switched. New problem though!

When measuring at transformer output though, I get full voltage:

13.9V for 14V
12.9 V for 13V
12.0V for 12V

But when measuring at the pool light junction box (about 2 feet from the actual light, and ~70ft. from the transformer), I only get

8.5 from 14V
8.5 from 13V
7.5 from 12V

I'm guessing loss of voltage in the wiring from the transformer to the junction box? It's only 70 feet or so, if that. However when I meter the hot and neutral together at the light, I get the full voltage that I read at the transformer.

My thoughts now are that the wiring from the junction box to transformer needs to be replaced. 2nd opinions?

 

[jza1736]

Are you metering at the j box with the light on? 70 ft will not give you a big voltage drop.

 

[jza1736]

With the light detached from the circuit you should get the full voltage

 

[adam_d]

Yes, the switch was on otherwise I would receive no voltage at the junction box. I only receive full voltage when metering the hot and neutral together. Otherwise hot reads about 9 or 10V and neutral reads about 2V.

I'm going to use an extension cord to bypass the junction box wiring tonight to see give me an answer is there is something wrong with the wiring, otherwise it'll be onto the socket or bulb.

 

[jza1736]

Disconnect the splice at the jbox and check it without the light attached to the circuit. If you have 12v back to the transformer, it's the light

 

[adam_d]

I agree that it's probably the light or bulb. I was a little confused on how to get the 12V after removing the splice at the junction box. I thought I would have 12V testing hot to ground, but I needed to test hot to neutral.

On to pulling the light out and checking the bulb/socket next.

 

[adam_d]

Opened up the pool light, the bulb twisted right out of the socket housing but with the mounting threads still inside, so it was very corroded. I ended up pulling it out of the socket housing, and it appears the white ring around where the bulb sits is also cracked. Not sure of the purpose to this part of the socket. Any idea of this would hurt anything?

Dropbox - IMG_0371.JPG

Dropbox - IMG_0372.jpg

I measured voltage by putting one end on the inside threads of the socket and the other on the lead that connects to the bulb. I get 12V. So I'm thinking bad bulb?
The bulb appears to have the filament intact and doesn't appear to be broken.

There was a tad bit of water in the housing. Im thinking may have caused the bulbs mounting piece of corrode and become unattached. The seal looks in good shape so if anything, I'm thinking it got in through the back conduit.

 

[jza1736]

Is the white part porcelain? It's an insulator and also helps with heat.

Check the voltage between the center pin of the Socket and the edge of the Socket. That will make sure its still good. Be careful not to cross the leads of the tester.