Pool light wiring question

Raymo71

New member
Sep 9, 2019
4
North Florida
Hello,
I just replaced my old Giammanco pool light transformer with the px300. The wires coming out of the pool side pipe are labeled 12,13,14,0 (all black), and a single white wire. From the old schematic, attached, looks like I connect the two black leads from the px300 to 12 (the voltage of my light) and 0(?). I’m confused what I do with the white (assuming neutral). Also no ground wire, unless that’s the 0. The pool is from the late 70’s and I believe the pool light housing and wiring is original.

Also, tested power on both the supply side and secondary side of the transformer and I’m getting 120Vac and 12Vac as expected.

Here’s the schematic
F1C6B232-3BC0-4425-BB0F-BBD36FE824DF.jpeg
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,864
SW Indiana
Welcome to TFP!

Your new transformer is a different setup than your old one. The old one had one input and then three different output voltages to select to compensate for voltage drop in the wiring. The new one has three inputs to select to adjust the output voltage. You hook the black input wire to either black, blue or yellow, depending on which one you need to get 12V to your light, white to neutral and ground to ground. The the two black wires on the output side go to the light.

The ground wire from the AC supply connects to the lugs on the back of the transformer. The one labeled 0V is one of the wires that goes to the light.
 
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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
20,474
Northern NJ
You want to have 12 volts at the light. You can have a voltage drop depending on the length of the wire and wire size from the transformer to the light. So the transformer lets you output 13V or 14V to compensate for the voltage drop.

As John said, the px300 gets wired differently.

 
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Raymo71

New member
Sep 9, 2019
4
North Florida
Thank you for the responses. That is how I wired it and on the 12v side (secondary?) I put the two blacks from the transformer to the two blacks from the light labeled 12 and 0. The white wire from the light is loose. Unfortunately my light won’t come on. Guess I spent unnecessary money, and at Pinch A Penny, no less. Waaay cheaper on Amazon.
I tested the bulb with a continuity test and it passed. What should I test next? I read something about reading ohms with the multimeter but I’m confused to that process. Thanks again for the help.
 

Raymo71

New member
Sep 9, 2019
4
North Florida
Welcome to TFP!

Your new transformer is a different setup than your old one. The old one had one input and then three different output voltages to select to compensate for voltage drop in the wiring. The new one has three inputs to select to adjust the output voltage. You hook the black input wire to either black, blue or yellow, depending on which one you need to get 12V to your light, white to neutral and ground to ground. The the two black wires on the output side go to the light.

The ground wire from the AC supply connects to the lugs on the back of the transformer. The one labeled 0V is one of the wires that goes to the light.
Sorry, I was mistaken on my wires coming from the light. There are two white wires ( one which was connected to the 12v black on the old Giammanco, which I labeled “hot”, the second white “neutral”) and 1 black wire that was connected to 0 on the old transformer. I’ve got the wiring correct on the supply side, as you mentioned, but since I have 3 wires out of the pool light and only 2 black wires of the px300 I don’t know which 2 to connect. Is that second white ground? And if I don’t connect to the box ground would that prevent my light from turning on? Sorry if these are dumb questions I get confused sometimes on how “ground” functions in the loop and it’s effect on things.
 

Raymo71

New member
Sep 9, 2019
4
North Florida
Which wires were connected from the light to the old transformer?
I made a mistake, there were two whites and a black from the light. One white was connected to the “12” and the black to the “0”. So I connected those two to the two blacks on the transformer on the secondary side. Unfortunately I can’t remember where that other white wire from the pool was connected to (should have snapped a pic) but I have it labeled neutral. Could it have been connected to neutral on the 120V side???
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,864
SW Indiana
You’d still have a 12V hot and 12V neutral coming out of the transformer. The only thing I’d guess for the third wire would be ground, but the color is wrong.

Are you sure your light works? I presume you had a reason to change the old transformer. Maybe there is a wiring or bulb issue in the light. I’d think your next step might be to pull the light up onto the deck and see where the wires go.