Lighting transformer gone bad?

[halleys5]

I’m installing a Hayward ltbuy11300 300w transformer after having it stored (new) for a couple years.
I have one colorlogic light attached to the secondary. When I put power to the primary side it immediately trips the breaker (20A). Pops like a dead short.
I installed the snubber that came with it, to no difference.
Resistance on the primary is near zero, so I thought maybe this is an inrush problem. But it’s only 300w and it pops 20A breakers in a dramatic arcing fashion.
Any ideas or fixes? I’ve read someone suggest an incandescent lightbulb in series at least as a test.
For $80 I can get a generic replacement and move on. That’s my next move unless you all can point me in the right direction.

 

[ajw22]

Is the breaker GFCI?

Sounds like the CB is tripping the GFCI which is usually due to the neutral not being wired correctly.

Is the generic replacement listed for pool use?

 

[nuttyp]

May be a dumb question, is there any chance you confused the primary with the secondary? That will pop the breaker and it's easy enough to do if you don't check wiring diagram carefully.

 

[halleys5]

Is the breaker GFCI?

Sounds like the CB is tripping the GFCI which is usually due to the neutral not being wired correctly.

Is the generic replacement listed for pool use?

No GFCI, I went to a straight breaker as a test.
I don't have the generic yet, the one I saw is the same formfactor as the Hayward, so I'm sure its meant to LOOK like it is listed for pool use. But a very good point.

 

[halleys5]

May be a dumb question, is there any chance you confused the primary with the secondary? That will pop the breaker and it's easy enough to do if you don't check wiring diagram carefully.

Dang.
The on the transformer itself, the 12, 13, 14V taps are labeled "12V" etc. I assumed those were the secondary taps. I guess there's no reason these couldn't be primary taps and there's just the single output from the secondary...

The Hayward wire diagrams are trash. There are conflicts between the transformer diagram, lights diagram, and switch/controller diagram...
I expected the secondary to have the multiple taps for voltage differences, not the primary.. shame on me, but I bet you are right on. I'll know later today.

Thanks for asking "dumb questions"!

 

[nuttyp]

Yup, I made the same assumption when bench testing one my neighbor gave me, since I'm accustomed to taps being on the secondary in other electronics. Not true for many of these, such as the Intermatic PX100 I was testing, wherein the taps are for the primary, and the secondary has just two wires, which are heavier gauge to handle the higher current at the lower voltage. Hope your test didn't damage the light if it was hooked up at the time. To make it slightly more misleading, the prior electrician had pulled the transformer primary wires to the right side, secondary to the left, which I think is unusual and helped to fool me. Pop goes the breaker, dark went the garage. but the transformer survived. I didn't have the output connected to anything.

 

[halleys5]

Yup, I made the same assumption when bench testing one my neighbor gave me, since I'm accustomed to taps being on the secondary in other electronics. Not true for many of these, such as the Intermatic PX100 I was testing, wherein the taps are for the primary, and the secondary has just two wires, which are heavier gauge to handle the higher current at the lower voltage. Hope your test didn't damage the light if it was hooked up at the time. To make it slightly more misleading, the prior electrician had pulled the transformer primary wires to the right side, secondary to the left, which I think is unusual and helped to fool me. Pop goes the breaker, dark went the garage. but the transformer survived. I didn't have the output connected to anything.

At least I'm in good company!
We shall see how the $400 colorlogic light likes the potential 1200 volts

 

[halleys5]

Forgot to post a follow up on this.
After correcting the feed and low voltage wiring through the transformer, the transformer was fine, the color logic light that has been attached was dead as was the switch controller.
So for now I have a standard light switch controlling 3 of 4 pool lights, and life is good again