Pool Light Testing Help

[oneskinnydave]

Hey All,

So - I think I have it narrowed down my issues - and I think I just have to replace the fixture....but I want to be sure I'm not missing something! I put in a new bulb to the fixture to test everything out - Here's what I have.

-Tested the bulb with continuity (base of the bulb) - good.
-Tested the output of the transformer (PX300) - 12V - good!
-I followed these directions:

- and didn't come across a ground fault. (Good...I guess?)
-Tested the continuity of just the fixture at the junction box (which is the transformer) - black to the white wire from the multimeter and got nothing. No change in the multimeter at all.

I had a previous post where they previous owner converted the 120v pool light to a 12v with the PX300...but didn't change the housing (it's a 120v Hayward Astrolite SP0583L) and was wondering if that was causing issues - but I think there is something in the wiring of the housing now. Signs are pointing towards a new fixture, but just wanted to check with folks much smarter then I am on the matter!

And if I need a new fixture definitely go with the 12v version of the Astrolite correct? I purchased an LED bulb that is 50w (one of the recommended ones here), but I think sticking with a 300w enclosure would be a safer bet...or get the 100w fixture and stick with LEDs moving foward?

Thanks all!

 

[ogdento]

-Tested the continuity of just the fixture at the junction box (which is the transformer) - black to the white wire from the multimeter and got nothing. No change in the multimeter at al

Hi, are you saying that you tested continuity between the hot and neutral wires coming off of the transformer? (I'll call them hot and neutral even though it doesn't really matter which one's which). With the power off, test it again and use resistance and not just continuity (some meters set to continuity also show the resistance, some don't)... if you are in fact testing the resistance of the transformer coil, you should be seeing some resistance.

 

[Jimrahbe]

One,

Is the light assembly up on the deck and open? Is the bulb in or out when you tested continuity between the black and white wires going to the pool light?

Jim R.

 

[oneskinnydave]

Hi, are you saying that you tested continuity between the hot and neutral wires coming off of the transformer? (I'll call them hot and neutral even though it doesn't really matter which one's which). With the power off, test it again and use resistance and not just continuity (some meters set to continuity also show the resistance, some don't)... if you are in fact testing the resistance of the transformer coil, you should be seeing some resistance.

Ah - sorry - I tested the continuity of the light housing with the new bulb in it! My transformer is just where my "junction box" is - wire goes all the way from the pool to my pool shed where the transformer is.

 

[oneskinnydave]

One,

Is the light assembly up on the deck and open? Is the bulb in or out when you tested continuity between the black and white wires going to the pool light?

Jim R.

The light is up on the deck and open with the new bulb in it. I saw a few tests that tell me what the resistance should be while testing continuity...but nothing changed on the multimeter at all. It stayed at -1, which is why I assumed there is a short somewhere.

 

[Jimrahbe]

one,

If you had a short you would have constant continuity.. I am not sure we are talking apples to apples.. When you touch the two test leads together, you should get zero ohms.. What do you get?

I suggest that you test the cable going to your light housing like this... Measure the resistance/continuity between the White and Black wires coming from the light fixture with the light bulb out... And again with the light bulb in and see what you get. With the light bulb out, you should get a very high resistance like in the meg ohm range.. With the light bulb in, you should get whatever you get when you measure across the bulb itself..

I have never measured across an LED bulb before, so I have no idea what resistance to expect...

Thanks,

Jim R.

 

[ogdento]

To add to Jim's last comment... for a cold incandescent bulb you'll get very low resistance (maybe 10 ohms) which makes sense because the filament is just a low-resistance wire (resistance increases when it's on). When you try and measure the resistance of an LED bulb you're really measuring the input to the LED driver circuit... definitely shouldn't be a short, but it's also not going to be the same as an incandescent. And if your meter shows -1 when set to resistance and stays at -1 when you connect the leads to something - that is an open circuit not a short.

 

[oneskinnydave]

Ah - yes - sorry, I think I got my terminology confused! This electrical stuff is a little new to me!

I think regardless of my bulb in or out (I used a regular 12v/300W pool light for testing) I always had -1 reading - but let me triple test with the light out. If I have an open circuit - does that mean the wire is just damaged in the line? It seems like I haven't seen that before in all my searching of the web lately - mostly found "ground fault" or shorts.

Thanks everyone for the replies back - makes me feel like I'm making some progress on this thing!

 

[ogdento]

i went back and re-read your original post and i'm a little confused... you didn't specifically say what your problem is, but I'm assuming it's that your light won't turn on

you said you measured the transformer output to be 12v, but it wasn't clear whether you measured 12v at the light housing that's sitting on your deck? if you're not getting 12v at the light housing then it is possible that the wire from the transformer is broken somewhere along the line - either the wire itself, or a loose/broken connection.

 

[Jimrahbe]

one,

When you measure resistance between the Black and White pool light wire, you should just see whatever the bulb reads. If you tested the bulb by itself and it measured 10 ohms, then you should see pretty close to the same 10 ohms when measuring between the Black and White wires...

If you don't get a reading, or it very high, that would indicate that at least one of the wires is not connected to the bulb. The most logical point would be right where the bulb connects to the housing.

Please answer Tom's question above...

Thanks,

Jim R.

 

[oneskinnydave]

Yes - light does not come on! It did for a while, then just kind of stopped.

I was not getting any voltage at the housing, but I could get 12v at the transformer secondary side. I might try and put in a light socket to plug adapter at the bulb just to triple check that I wasn't/was touching the right parts of the socket. It seems kind of fool proof....but I am kind of a ding dong some times!