Here are my posts on a Yahoo pool group concerning a problem with my pool light. It's not resolved yet. I'd appreciate any ideas.
I have one more post to the group which I'll bring here as soon as it's published and I can copy it. Basically, it concludes that neither the light itself or the thermal/overload protector on the transformer is the problem and moves the focus to the transformer itself.
Mar. 3, 2008
My pool light (12v 300w) turns on fine but within a minute it shuts down. Then
in a minute
or so, its back on but just for a few seconds. Then it's off for 30 seconds or
so, on for five
seconds and off again.
I've replaced the bulb thinking it was an intermittent filament break. New bulb
same. There was no water in the bulb compartment.
Can this be a problem caused by a faulty low water sensor in the light assembly?
Any ideas will be appreciated.
Mar. 10, 2008
Re: Pool light malfunction
Thanks for the comments so far. I think Mike is on to something when he
transformer may have an issue.
I measured the amperage with a clamp on ammeter on both the primary and
sides of the transformer. When the light is on, the primary side shows about
-about what one would expect with a 300 watt bulb. The secondary peaks at about
amps initially but in a few tenths of a second is down to 17 amps as the bulb
Again, about what one would expect. But after 30 seconds or so everything shuts
and current goes to zero.
The light is connected to the 12-volt tap on the transformer. I tried the
13-volt tap but it
just made the on/off cycle quicker so I went back to the 12-volt tap.
The transformer is cool to the touch during all this.
Then I disconnected the light and measured the current on the primary. It was
and .2 amps and stayed on forever. It didn't cut out. I figure .1 to .2 amps is
for just energizing the primary so no big revelation here.
Next I connected a spare 12v/300w bulb to the secondary. The pool light and
wiring was out of the circuit during this test.
The primary and secondary amperages were the same as for the pool light---and
seconds or so, the light shut down. Now, as Mike suggested, it became pretty
the overload protector in the transformer was cutting out. In fact, I think I
can hear the
mechanical snap as it does so. I suspect it's a bimetal switch. But again, the
itself was cool to the touch. There's absolutely no indication of overheating
current draw certainly does not seem excessive.
So, I think Mikes right. There's a problem with the overload protector.
I'm calling the manufacturer on Monday and see what they have to say. If
they're no help
I'm going to remove the transformer and see if I can find the protector. If I
can find it and
if I can physically isolate it from the transformer while still keeping it wired
in, I should be
able to determine if heat is the issue. I suspect it has a fault that causes it
to be intolerant
of normal current draw.
Thanks again for the ideas. I'll keep you posted.
Mar. 9, 2008
Re: Pool light malfunction
Well, here's the latest in my pool light saga.
After testing current flow and verifying that the pool light itself was not the
concluded, with Mike's help, that the problem lay in the transformer. Further
strongly implicated the current overload protection device in the transformer
So today I called Intermatic, the light manufacturer aand learned that they have
serviceable parts for the transformer. Sending the entire assembly to them for
the only option and they candidly said that would likely cost more than the
of a new unit ($125). I pleaded with the customer rep that there must be
and she referred me to a technical guy who clearly understood the product and my
problem. He referred me to the company that makes the transformer for them.
A call to to that company (I'll privately provide the name if anyone needs it)
got me to
another customer rep who listened politely but informed me they were a
couldn't sell direct to a consumer. I asked if she could make an exception and
referred me to her boss. He actually seemed willing to help and suggested I
talk to their
engineer in charge of that product. NOW I was getting somewhere!
The engineer listened to my problem and asked a bunch of questions about the
I had done. We talked for nearly 10 minutes. He ultimately agreed that the
protector was the likely problem and offered to send me a replacement from his
No charge. Now that's customer service.
If all goes well and I get the part as he offered, and if it is indeed the
problem I'll be back
in business for no cost. Alternatively, if, for some reason I don't get the
protector, I intend
to cut the existing one out of the circuit and bypass it. It's there only to
transformer. It has nothing to do with pool safety. But just to be on the safe
protect the entire circuit with a GFI. That should protect the transformer and
give a good
margin of personal safety as well.
I'll keep you posted. I hope to have the overload protector by late this week.